Subjects -> ENVIRONMENTAL STUDIES (Total: 913 journals)
    - ENVIRONMENTAL STUDIES (810 journals)
    - POLLUTION (31 journals)
    - TOXICOLOGY AND ENVIRONMENTAL SAFETY (54 journals)
    - WASTE MANAGEMENT (18 journals)

ENVIRONMENTAL STUDIES (810 journals)                  1 2 3 4 5 | Last

Showing 1 - 200 of 378 Journals sorted alphabetically
ACS Chemical Health & Safety     Hybrid Journal   (Followers: 4)
ACS Environmental Au     Open Access   (Followers: 10)
ACS ES&T Engineering     Hybrid Journal   (Followers: 1)
Acta Brasiliensis     Open Access  
Acta Ecologica Sinica     Open Access   (Followers: 9)
Acta Oecologica     Hybrid Journal   (Followers: 12)
Advanced Electronic Materials     Hybrid Journal   (Followers: 12)
Advanced Energy and Sustainability Research     Open Access   (Followers: 5)
Advanced Membranes     Open Access   (Followers: 8)
Advanced Sustainable Systems     Hybrid Journal   (Followers: 7)
Advances in Ecological Research     Full-text available via subscription   (Followers: 43)
Advances in Environmental Chemistry     Open Access   (Followers: 13)
Advances in Environmental Sciences - International Journal of the Bioflux Society     Open Access   (Followers: 16)
Advances in Environmental Technology     Open Access   (Followers: 2)
Advances in Life Science and Technology     Open Access   (Followers: 11)
Advances in Tropical Biodiversity and Environmental Sciences     Open Access   (Followers: 4)
Aeolian Research     Hybrid Journal   (Followers: 7)
Agricultura Tecnica     Open Access   (Followers: 2)
Agricultural & Environmental Letters     Open Access   (Followers: 4)
Agro-Science     Full-text available via subscription   (Followers: 2)
Agroecological journal     Open Access   (Followers: 1)
Agronomy for Sustainable Development     Open Access   (Followers: 19)
Agrosystems, Geosciences & Environment     Open Access   (Followers: 6)
Amazon's Research and Environmental Law     Open Access   (Followers: 3)
Ambiens. Revista Iberoamericana Universitaria en Ambiente, Sociedad y Sustentabilidad     Open Access  
Ambiente & sociedade     Open Access   (Followers: 2)
American Journal of Energy and Environment     Open Access   (Followers: 4)
American Journal of Environmental Engineering     Open Access   (Followers: 6)
American Journal of Environmental Protection     Open Access   (Followers: 5)
American Journal of Environmental Sciences     Open Access   (Followers: 9)
American Naturalist     Full-text available via subscription   (Followers: 79)
Animal - Open Space     Open Access   (Followers: 5)
Annals of Civil and Environmental Engineering     Open Access   (Followers: 1)
Annals of Environmental Science and Toxicology     Open Access   (Followers: 3)
Annals of GIS     Open Access   (Followers: 31)
Annual Review of Ecology, Evolution, and Systematics     Full-text available via subscription   (Followers: 82)
Annual Review of Environment and Resources     Full-text available via subscription   (Followers: 16)
Annual Review of Pharmacology and Toxicology     Full-text available via subscription   (Followers: 38)
Annual Review of Resource Economics     Full-text available via subscription   (Followers: 11)
Applied and Environmental Soil Science     Open Access   (Followers: 15)
Applied Ecology and Environmental Sciences     Open Access   (Followers: 29)
Applied Environmental Education & Communication     Hybrid Journal   (Followers: 17)
Applied Journal of Environmental Engineering Science     Open Access   (Followers: 1)
Aquatic Ecology     Hybrid Journal   (Followers: 42)
Aquatic Toxicology     Hybrid Journal   (Followers: 26)
Arcada : Revista de conservación del patrimonio cultural     Open Access  
Architecture, Civil Engineering, Environment     Open Access   (Followers: 4)
Archives des Maladies Professionnelles et de l'Environnement     Full-text available via subscription  
Archives of Environmental and Occupational Health     Hybrid Journal   (Followers: 10)
Archives of Environmental Contamination and Toxicology     Hybrid Journal   (Followers: 12)
Archives of Environmental Protection     Open Access   (Followers: 5)
Archives of Toxicology     Hybrid Journal   (Followers: 20)
Arctic Environmental Research     Open Access  
Asian Journal of Environment & Ecology     Open Access   (Followers: 2)
Asian Journal of Rural Development     Open Access   (Followers: 10)
Asian Review of Environmental and Earth Sciences     Open Access   (Followers: 2)
ATBU Journal of Environmental Technology     Open Access   (Followers: 1)
Atmospheric and Climate Sciences     Open Access   (Followers: 38)
Atmospheric Environment     Hybrid Journal   (Followers: 72)
Atmospheric Environment : X     Open Access   (Followers: 3)
Augm Domus : Revista electrónica del Comité de Medio Ambiente de AUGM     Open Access  
Austral Ecology     Hybrid Journal   (Followers: 17)
Australasian Journal of Environmental Management     Hybrid Journal   (Followers: 9)
Australasian Journal of Human Security     Full-text available via subscription   (Followers: 2)
Australian Journal of Environmental Education     Full-text available via subscription   (Followers: 10)
Basic & Clinical Pharmacology & Toxicology     Hybrid Journal   (Followers: 14)
Basic and Applied Ecology     Hybrid Journal   (Followers: 22)
Behavioral Ecology     Hybrid Journal   (Followers: 57)
Behavioral Ecology and Sociobiology     Hybrid Journal   (Followers: 35)
Biocenosis     Open Access  
Biochar     Hybrid Journal   (Followers: 1)
Biodegradation     Hybrid Journal   (Followers: 2)
Biodiversity     Hybrid Journal   (Followers: 28)
Biofouling: The Journal of Bioadhesion and Biofilm Research     Hybrid Journal   (Followers: 2)
Bioremediation Journal     Hybrid Journal   (Followers: 4)
BioRisk     Open Access   (Followers: 2)
Boletín Semillas Ambientales     Open Access  
Bothalia : African Biodiversity & Conservation     Open Access  
Built Environment     Full-text available via subscription   (Followers: 6)
Bulletin of Environmental Contamination and Toxicology     Hybrid Journal   (Followers: 10)
Bulletin of the American Meteorological Society     Open Access   (Followers: 63)
Bumi Lestari Journal of Environment     Open Access  
Canadian Journal of Earth Sciences     Hybrid Journal   (Followers: 22)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 56)
Canadian Journal of Soil Science     Full-text available via subscription   (Followers: 12)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 18)
Capitalism Nature Socialism     Hybrid Journal   (Followers: 21)
Carbon Capture Science & Technology     Open Access  
Carbon Resources Conversion     Open Access   (Followers: 2)
Case Studies in Chemical and Environmental Engineering     Open Access  
Cell Biology and Toxicology     Hybrid Journal   (Followers: 10)
Chain Reaction     Full-text available via subscription  
Challenges in Sustainability     Open Access   (Followers: 10)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 22)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 3)
Chemosphere     Hybrid Journal   (Followers: 19)
Child and Adolescent Mental Health     Hybrid Journal   (Followers: 69)
Chinese Journal of Environmental Law     Hybrid Journal   (Followers: 1)
Ciencia, Ambiente y Clima     Open Access   (Followers: 1)
City and Environment Interactions     Open Access   (Followers: 3)
Civil and Environmental Engineering     Open Access   (Followers: 7)
Civil and Environmental Engineering Reports     Open Access   (Followers: 4)
Civil and Environmental Research     Open Access   (Followers: 14)
CLEAN - Soil, Air, Water     Hybrid Journal   (Followers: 18)
Clean Technologies     Open Access   (Followers: 1)
Clean Technologies and Environmental Policy     Hybrid Journal   (Followers: 5)
Cleaner and Circular Bioeconomy (CLCB)     Open Access   (Followers: 8)
Cleaner Energy Systems     Open Access   (Followers: 6)
Cleaner Environmental Systems     Open Access  
Cleaner Production Letters     Hybrid Journal  
Cleaner Waste Systems     Open Access   (Followers: 5)
Cleanroom Technology     Full-text available via subscription   (Followers: 1)
Climate and Energy     Full-text available via subscription   (Followers: 10)
Climate Change Ecology     Open Access   (Followers: 29)
Climate Change Economics     Hybrid Journal   (Followers: 51)
Climate Policy     Hybrid Journal   (Followers: 60)
Climate Resilience and Sustainability     Open Access   (Followers: 34)
Coastal Engineering Journal     Hybrid Journal   (Followers: 9)
Cogent Environmental Science     Open Access  
Columbia Journal of Environmental Law     Open Access   (Followers: 13)
Computational Ecology and Software     Open Access   (Followers: 9)
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 5)
Conservation and Society     Open Access   (Followers: 14)
Conservation Letters     Open Access   (Followers: 50)
Conservation Science     Open Access   (Followers: 29)
Consilience : The Journal of Sustainable Development     Open Access   (Followers: 2)
Contemporary Problems of Ecology     Hybrid Journal   (Followers: 4)
Critical Reviews in Environmental Science and Technology     Hybrid Journal   (Followers: 11)
Critical Reviews in Toxicology     Hybrid Journal   (Followers: 25)
Cuadernos de Investigación Geográfica / Geographical Research Letters     Open Access  
Culture, Agriculture, Food and Environment     Hybrid Journal   (Followers: 24)
Culture, Agriculture, Food and Environment     Hybrid Journal   (Followers: 8)
Current Environmental Health Reports     Hybrid Journal   (Followers: 2)
Current Forestry Reports     Hybrid Journal   (Followers: 1)
Current Landscape Ecology Reports     Hybrid Journal   (Followers: 2)
Current Opinion in Environmental Science & Health     Hybrid Journal  
Current Opinion in Environmental Sustainability     Hybrid Journal   (Followers: 14)
Current Research in Ecological and Social Psychology     Open Access   (Followers: 3)
Current Research in Environmental Sustainability     Open Access   (Followers: 4)
Current Research in Green and Sustainable Chemistry     Open Access   (Followers: 1)
Current Research in Microbiology     Open Access   (Followers: 20)
Current Sustainable/Renewable Energy Reports     Hybrid Journal   (Followers: 7)
Die Bodenkultur : Journal of Land Management, Food and Environment     Open Access  
Disaster Prevention and Management     Hybrid Journal   (Followers: 27)
Discover Sustainability     Open Access   (Followers: 3)
disP - The Planning Review     Hybrid Journal   (Followers: 1)
Drug and Chemical Toxicology     Hybrid Journal   (Followers: 13)
Duke Environmental Law & Policy Forum     Open Access   (Followers: 8)
E3S Web of Conferences     Open Access  
Earth and Environmental Science Transactions of the Royal Society of Edinburgh     Hybrid Journal   (Followers: 7)
Earth Interactions     Open Access   (Followers: 10)
Earth Science Informatics     Hybrid Journal   (Followers: 7)
Earth System Governance     Open Access   (Followers: 1)
Earth System Science Data (ESSD)     Open Access   (Followers: 9)
Earth Systems and Environment     Hybrid Journal   (Followers: 3)
EchoGéo     Open Access  
Eco-Environment & Health     Open Access   (Followers: 6)
Eco-Thinking     Open Access   (Followers: 2)
Ecocycles     Open Access   (Followers: 4)
Ecohydrology     Hybrid Journal   (Followers: 11)
Ecohydrology & Hydrobiology     Full-text available via subscription   (Followers: 5)
Ecologia Aplicada     Open Access  
Ecología en Bolivia     Open Access  
Ecological Applications     Full-text available via subscription   (Followers: 162)
Ecological Chemistry and Engineering S     Open Access   (Followers: 3)
Ecological Complexity     Hybrid Journal   (Followers: 8)
Ecological Engineering     Hybrid Journal   (Followers: 5)
Ecological Indicators     Hybrid Journal   (Followers: 22)
Ecological Informatics     Hybrid Journal   (Followers: 4)
Ecological Management & Restoration     Hybrid Journal   (Followers: 15)
Ecological Modelling     Hybrid Journal   (Followers: 73)
Ecological Monographs     Full-text available via subscription   (Followers: 37)
Ecological Processes     Open Access   (Followers: 2)
Ecological Questions     Open Access   (Followers: 5)
Ecological Research     Hybrid Journal   (Followers: 10)
Ecological Restoration     Full-text available via subscription   (Followers: 22)
Ecologist, The     Full-text available via subscription   (Followers: 22)
Ecology     Full-text available via subscription   (Followers: 389)
Ecology and Evolution     Open Access   (Followers: 100)
Ecology Letters     Hybrid Journal   (Followers: 274)
EcoMat : Functional Materials for Green Energy and Environment     Open Access  
Economics and Policy of Energy and the Environment     Full-text available via subscription   (Followers: 14)
Economics of Energy & Environmental Policy     Hybrid Journal   (Followers: 1)
Économie rurale     Open Access   (Followers: 3)
Ecoprint : An International Journal of Ecology     Open Access   (Followers: 4)
Ecopsychology     Hybrid Journal   (Followers: 7)
Ecosphere     Open Access   (Followers: 12)
Ecosystem Services     Hybrid Journal   (Followers: 8)
Ecosystems     Hybrid Journal   (Followers: 33)
Ecosystems and People     Open Access   (Followers: 4)
Ecotoxicology     Hybrid Journal   (Followers: 9)
Ecotoxicology and Environmental Safety     Hybrid Journal   (Followers: 10)
Ecotrophic : Journal of Environmental Science     Open Access  
Ecozon@ : European Journal of Literature, Culture and Environment     Open Access   (Followers: 3)
Éducation relative à l'environnement     Open Access  
Electronic Green Journal     Open Access   (Followers: 4)
Empowering Sustainability International Journal     Open Access   (Followers: 4)
Energy & Environment     Hybrid Journal   (Followers: 26)
Energy & Environmental Science     Hybrid Journal   (Followers: 33)
Energy and Climate Change     Hybrid Journal   (Followers: 11)

        1 2 3 4 5 | Last

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Clean Technologies
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2571-8797
Published by MDPI Homepage  [249 journals]
  • Clean Technol., Vol. 5, Pages 74-93: Functional and Environmental
           Performances of Novel Electrolytic Membranes for PEM Fuel Cells: A
           Lab-Scale Case Study

    • Authors: Matteo Di Virgilio, Andrea Basso Peressut, Valeria Arosio, Alessandro Arrigoni, Saverio Latorrata, Giovanni Dotelli
      First page: 74
      Abstract: Despite being the most employed polymer electrolyte for proton exchange membrane fuel cells (PEMFCs), Nafion® has several limitations: expensiveness, poor performance when exposed to temperatures higher than 80 °C, and its potential as a source of environmentally persistent and toxic compounds (i.e., per- and polyfluoroalkyl substances, known as PFASs) when disposed of. This work explores the functional and environmental performances of three potential PFAS-free alternatives to Nafion® as electrolytic membranes in PEMFCs: sulfonated graphene oxide (SGO), graphene oxide-naphthalene sulfonate (GONS), and borate-reinforced sulfonated graphene oxide (BSGO). Investigated via ATR-FTIR spectroscopy, TGA, and cross-sectional SEM, the membranes show an effective functionalization of GO and good thermal stability. Functional properties are determined via Ion Exchange Capacity (IEC) evaluation, Electrochemical Impedance Spectroscopy, and tensile tests. In terms of IEC, the innovative materials outperform Nafion® 212. Proton conductivities at 80 °C of SGO (1.15 S cm−1) and GONS (1.71 S cm−1) are higher than that of the commercial electrolyte (0.56 S cm−1). At the same time, the membranes are investigated via Life Cycle Assessment (LCA) to uncover potential environmental hotspots. Results show that energy consumption during manufacture is the main environmental concern for the three membranes. A sensitivity analysis demonstrates that the impact could be significantly reduced if the production procedures were scaled up. Among the three alternatives, SGO shows the best trade-off between proton conductivity and environmental impact, even though performance results from real-life applications are needed to determine the actual environmental consequences of replacing Nafion® in PEMFCs.
      Citation: Clean Technologies
      PubDate: 2023-01-09
      DOI: 10.3390/cleantechnol5010005
      Issue No: Vol. 5, No. 1 (2023)
       
  • Clean Technol., Vol. 5, Pages 94-115: An Enhanced Piezoelectric-Generated
           Power Technique for Qi Wireless Charging

    • Authors: Wafa Elmannai, Khaled Elleithy, Andrew Anthony Benz, Alberto Carmine DeAngelis, Nick Weaver
      First page: 94
      Abstract: This paper aims to design and implement a robust wireless charging system that utilizes affordable materials and the principle of piezoelectricity to generate clean energy to allow the user to store the energy for later use. A wireless charging system that utilizes the piezoelectricity generated as a power source and integrated with Qi-standard wireless transmission would substantially affect the environment and the users. The approach consists of a full-wave-rectified piezoelectric generation, battery storage, Qi-standard wireless transmission, and Bluetooth Low Energy (BLE) as the controller and application monitor. Three main functions are involved in the design of the proposed system: power generation, power storage, and power transmission. A client application is conceived to monitor the transmission and receipt of data. The piezoelectric elements generate the AC electricity from the mechanical movements, which converts the electricity to DC using the full-wave bridge rectifiers. The sensor transmits the data to the application via BLE protocols. The user receives continuous updates regarding the storage level, paired devices, and remaining time for a complete charge. A Qi-standard wireless transmitter transfers the stored electricity to charge the respective devices. The output generates pulses to 60 voltage on each compression of a transducer. The design is based on multiple parallel configurations to solve the issue of charging up to the triggering value VH = 5.2 V when tested with a single piezoelectric transducer. AA-type battery cells are charged in parallel in a series configuration. The system is tested for a number of scenarios. In addition, we simulate the design for 11.11 h for approximately 70,000 joules of input. The system can charge from 5% to 100% and draw from 98%. Using four piezos in the designed module results in an average output voltage of 1.16 V. Increasing the number of piezos results in 17.2 W of power. The system is able to wirelessly transmit and store power with a stable power status after less than 0.01 s.
      Citation: Clean Technologies
      PubDate: 2023-01-10
      DOI: 10.3390/cleantechnol5010006
      Issue No: Vol. 5, No. 1 (2023)
       
  • Clean Technol., Vol. 5, Pages 116-136: Artificial Neural Networks as
           Artificial Intelligence Technique for Energy Saving in Refrigeration
           Systems—A Review

    • Authors: Mario Pérez-Gomariz, Antonio López-Gómez, Fernando Cerdán-Cartagena
      First page: 116
      Abstract: The refrigeration industry is an energy-intensive sector. Increasing the efficiency of industrial refrigeration systems is crucial for reducing production costs and minimizing CO2 emissions. Optimization of refrigeration systems is often a complex and time-consuming problem. This is where technologies such as big data and artificial intelligence play an important role. Nowadays, smart sensorization and the development of IoT (Internet of Things) make the massive connection of all kinds of devices possible, thereby enabling a new way of data acquisition. In this scenario, refrigeration systems can be measured comprehensively by acquiring large volumes of data in real-time. Then, artificial neural network (ANN) models can use the data to drive autonomous decision-making to build more efficient refrigeration systems.
      Citation: Clean Technologies
      PubDate: 2023-01-11
      DOI: 10.3390/cleantechnol5010007
      Issue No: Vol. 5, No. 1 (2023)
       
  • Clean Technol., Vol. 5, Pages 137-139: Acknowledgment to the Reviewers of
           Clean Technologies in 2022

    • Authors: Clean Technologies Editorial Office Clean Technologies Editorial Office
      First page: 137
      Abstract: High-quality academic publishing is built on rigorous peer review [...]
      Citation: Clean Technologies
      PubDate: 2023-01-16
      DOI: 10.3390/cleantechnol5010008
      Issue No: Vol. 5, No. 1 (2023)
       
  • Clean Technol., Vol. 5, Pages 140-166: Synthesis of Metal Organic
           Frameworks (MOFs) and Their Derived Materials for Energy Storage
           Applications

    • Authors: Sunil Dutt, Ashwani Kumar, Shivendra Singh
      First page: 140
      Abstract: The linkage between metal nodes and organic linkers has led to the development of new porous crystalline materials called metal–organic frameworks (MOFs). These have found significant potential applications in different areas such as gas storage and separation, chemical sensing, heterogeneous catalysis, biomedicine, proton conductivity, and others. Overall, MOFs are outstanding candidates for next-generation energy storage devices, and they have recently attracted the greater devotion of the scientific community worldwide. MOFs can be used to enhance the ability of a device to store energy due to their unique morphology, controllable structures, high surface area, and permanent porosity. MOFs are widely used in super capacitors (SCs), metal (Li, Na, and K) ion batteries, and lithium–sulfur batteries (LSBs) and act as a promising candidate to store energy in an environmentally friendly way. MOFs are also used as efficient materials with better recyclability, efficiency, and capacity retention. In this review, first we summarize the material design, chemical compositions, and physical structure of MOFs and afterward, we highlight the most recent development and understanding in this area, mainly focusing on various practical applications of MOFs in energy storage devices.
      Citation: Clean Technologies
      PubDate: 2023-01-20
      DOI: 10.3390/cleantechnol5010009
      Issue No: Vol. 5, No. 1 (2023)
       
  • Clean Technol., Vol. 5, Pages 1-24: CO2-Selective Capture from Light
           Hydrocarbon Mixtures by Metal-Organic Frameworks: A Review

    • Authors: Hengcong Huang, Luyao Wang, Xiaoyu Zhang, Hongshuo Zhao, Yifan Gu
      First page: 1
      Abstract: CO2 represents a typical impurity in light hydrocarbon feedstocks, which affects the quality of subsequent chemical products. Owing to their highly similar nature, industrial separation requires large amounts of energy. Adsorptive gas separation based on porous materials is considered an efficient alternative, as it can offer faster kinetics, higher selectivity, long-term stability and more energy-efficient regeneration. For the adsorption separation method, preferential CO2 capture from gas mixtures in one step is more energy-efficient for direct purification than light hydrocarbons, saving about 40% energy by eliminating energy-intensive post-regeneration processes such as countercurrent vacuum blowdown. Therefore, CO2-selective adsorbents are more sought-after than light hydrocarbon-selective adsorbents. Metal-organic frameworks (MOFs) have been demonstrated as outstanding physisorbents for CO2 capture due to their configurable channels for CO2 recognition, structural flexibility and large specific surface area. Many highly selective CO2 adsorption behaviors of MOFs have been reportedly achieved by precise modulation of pore size, pore chemistry or structural flexibility. In this review, we discuss the emerging development of MOFs for CO2-selective capture from different light hydrocarbon mixtures. The challenges of CO2 recognition and the strategies employed to achieve CO2 selectivity over light hydrocarbon mixtures by MOFs are summarized. In addition, the current challenges and prospects in the field of MOFs for CO2 capture are discussed and elaborated.
      Citation: Clean Technologies
      PubDate: 2022-12-20
      DOI: 10.3390/cleantechnol5010001
      Issue No: Vol. 5, No. 1 (2022)
       
  • Clean Technol., Vol. 5, Pages 25-37: A Comprehensive Model to Estimate
           Electric Vehicle Battery’s State of Charge for a Pre-Scheduled Trip
           Based on Energy Consumption Estimation

    • Authors: Quynh T. Tran, Leon Roose, Chayaphol Vichitpunt, Kumpanat Thongmai, Krittanat Noisopa
      First page: 25
      Abstract: EV development is being prioritized in order to attain the target of net zero emissions by 2050. Electric vehicles have the potential to decrease greenhouse gas (GHG) emissions, which contribute to global warming. The driving range of electric vehicles is a significant limitation that prevents people from using them generally. This paper proposes a comprehensive model for calculating the amount of energy needed to charge EVs for a scheduled trip. The model contains anticipated consumption energy for the whole trip as well as contingency energy to account for unpredictable conditions. The model is simple to apply to various types of electric vehicles and produces results with sufficient precision. A number of driving tests with different road characteristics and weather conditions were implemented to evaluate the success of the proposed method. The findings could help the users feel more confidence when driving EVs, promote the usage of EVs, and advocate for the increased use of green and renewable energy sources.
      Citation: Clean Technologies
      PubDate: 2022-12-23
      DOI: 10.3390/cleantechnol5010002
      Issue No: Vol. 5, No. 1 (2022)
       
  • Clean Technol., Vol. 5, Pages 38-50: Using Self-Organizing Map Algorithm
           to Reveal Stabilities of Parameter Sensitivity Rankings in Microbial
           Kinetic Models: A Case for Microalgae

    • Authors: Dhan Lord B. Fortela, Alyssa M. DeLattre, Wayne W. Sharp, Emmanuel D. Revellame, Mark E. Zappi
      First page: 38
      Abstract: Microalgae are multi-purpose microbial agents due to their capability to efficiently sequester carbon dioxide and produce valuable biomass such as protein and single-cell oils. Formulation and tuning of microalgae kinetics models can significantly contribute to the successful design and operation of microalgae reactors. This work aimed to demonstrate the capability of self-organizing map (SOM) algorithm to elucidate the patterns of parameter rankings in microalgae models subject to stochastic variations of input forcing functions–bioprocess influent component concentration levels. These stochastic variations were implemented on a modeled chemostat with a deterministic microalgae kinetic model consists of ten time-dependent variables and eighteen model parameters. The methodology consists of two major stages: (1) global sensitivity analysis (GSA) on the importance of model parameters with stochastic sampling of bioreactor influent component concentrations, and (2) training of self-organizing maps on the datasets of model parameter rankings derived from the GSA indices. Results reveal that functional principal components analysis can project at least 99% of the time-dependent dynamic patterns of the model variables on B-splines basis functions. The component planes for hexagonal lattice SOMs reveal that the sensitivity rankings some parameters in the algae model tested can be stable over a wide range of variations in the levels of influent component concentrations. Therefore, SOM can be used to reveal the trends in multi-dimensional data arrays arising from the implementation of GSA of kinetic models under stochastic perturbation of input forcing functions.
      Citation: Clean Technologies
      PubDate: 2022-12-26
      DOI: 10.3390/cleantechnol5010003
      Issue No: Vol. 5, No. 1 (2022)
       
  • Clean Technol., Vol. 5, Pages 51-73: A Novel H2O/LiBr Absorption Heat Pump
           with Condensation Heat Recovery for Combined Heating and Cooling
           Production: Energy Analysis for Different Applications

    • Authors: Juan Prieto, Dereje S. Ayou, Alberto Coronas
      First page: 51
      Abstract: The aim of this study is to analyze the feasibility of the single-effect H2O/LiBr absorption heat pump cycle to produce combined heating and cooling. To achieve this, first, the main changes that the absorption cycle requires are described in comparison with the conventional single-effect absorption chiller. Then, the cycle’s operational limits in terms of temperature lift and LiBr crystallization are evaluated. In this sense, driving heat temperatures required for these applications range from 85 °C to 120 °C. The energy and exergy performance (in terms of cooling and heating capacities, cooling and heating coefficient of performance, and exergy coefficient of performance) of the cycle is theoretically studied for five different types of applications that require simultaneous heating and cooling: building air conditioning, a 4th generation district heating and cooling network, a sports center with an indoor swimming pool, a hybrid air conditioning system with an absorption heat pump and a desiccant evaporative cooling system, and simultaneous cooling and water purification application for coastal areas. The system performance in terms of the cooling coefficient of performance varies in the range of 0.812–0.842, in terms of heating coefficient of performance from 0.58 to 1.842, and in terms of exergy coefficient of performance from 0.451 to 0.667. The application with the highest exergy coefficient of performance is the 4th generation district heating and cooling network.
      Citation: Clean Technologies
      PubDate: 2022-12-31
      DOI: 10.3390/cleantechnol5010004
      Issue No: Vol. 5, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 893-907: Understanding Societal Requirements
           of CCS Projects: Application of the Societal Embeddedness Level Assessment
           Methodology in Four National Case Studies

    • Authors: Dimitrios Mendrinos, Spyridon Karytsas, Olympia Polyzou, Constantine Karytsas, Åsta Dyrnes Nordø, Kirsti Midttømme, Danny Otto, Matthias Gross, Marit Sprenkeling, Ruben Peuchen, Tara Geerdink, Hanneke Puts
      First page: 893
      Abstract: The DigiMon project aims to develop and demonstrate an affordable, flexible, societally embedded, and smart digital monitoring early warning system for any subsurface CO2 storage field. The societal embeddedness level (SEL) assessment is a novel methodology which provides insight into the societal requirements for technological innovation to be deployed. The SEL assessment framework was applied in four case studies, concerning CCS development in Norway, the Netherlands, Greece, and Germany. The resulting societal embeddedness levels of CCS, on a scale of 1–4, were SEL 3 in Norway with considerable progress towards level 4, followed by the Netherlands with SEL 2 with several initiatives towards offshore demonstration projects, and then by Greece and Germany with SEL 1. The outcomes of the SEL assessments show which societal requirements have been met in current CCS developments and which ones should be improved for CCS deployment. They also show that monitoring currently is a regulatory requirement as part of permitting procedures, while it may alleviate community concerns on safety, provided that it has certain attributes. The insights from the four national case studies are further used in the DigiMon project to develop the innovative societal embedded DigiMon monitoring system.
      Citation: Clean Technologies
      PubDate: 2022-09-20
      DOI: 10.3390/cleantechnol4040055
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 908-930: Lithium-Ion Batteries—The
           Crux of Electric Vehicles with Opportunities and Challenges

    • Authors: S. Rangarajan, Sunddararaj, Sudhakar, Shiva, Subramaniam, Collins, Senjyu
      First page: 908
      Abstract: With the widespread use of lithium-ion batteries in a wide range of consumer electronics products, the CE industry has undergone a dramatic shift. The Li-ion battery has emerged as the heart of electric cars, and the focus has now shifted to the automotive sector. Liquid crystal displays have evolved over time to meet the demands of automobiles. International research groups and the performance of production electric vehicles are used to discuss and inform vehicle-driven battery targets. There is still a lot of room for improvement in terms of energy, life expectancy, cost, safety, and fast-charging capabilities for LIBs suited for the automotive sector. In this study, a review of lithium-ion battery applications in electric vehicles is presented.
      Citation: Clean Technologies
      PubDate: 2022-09-21
      DOI: 10.3390/cleantechnol4040056
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 931-941: Investigation of Electrical and
           Thermal Performance of a Commercial PEM Electrolyzer under Dynamic
           Solicitations

    • Authors: Feriel Mustapha, Damien Guilbert, Mohammed El-Ganaoui
      First page: 931
      Abstract: Hydrogen generation through electrolyzers has gained a growing interest from researchers and industries to decarbonize transportation and electricity production. The performance of electrolyzers is strongly dependent on their operating conditions, such as the supply current, temperature, and pressure. To meet near-zero emissions, the electrolyzer must be supplied by low-carbon energy sources. Therefore, renewable energy sources must be considered. However, these sources are strongly linked with the weather conditions, so they have a high dynamic behavior. Therefore, this article is focused on the investigation of the effects of these dynamic solicitations on the electrical and thermal performance of electrolyzers. In this study, a proton exchange membrane (PEM) has been chosen to carry out this investigation. Experimental tests have been performed, emphasizing the relationship between the electrical and thermal performance of the PEM electrolyzer. The purpose of this work is to provide an optimal scenario of the operation of the electrolyzer under dynamic solicitations and consequently, to decrease the degradation of the electrolyzer.
      Citation: Clean Technologies
      PubDate: 2022-09-26
      DOI: 10.3390/cleantechnol4040057
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 942-953: Sustainable Synthesis of FITC
           Chitosan-Capped Gold Nanoparticles for Biomedical Applications

    • Authors: Valeria De Matteis, Loris Rizzello, Mariafrancesca Cascione, Paolo Pellegrino, Jagpreet Singh, Daniela Manno, Rosaria Rinaldi
      First page: 942
      Abstract: The quest for novel nanoscale materials for different applications necessitates that they are easy to obtain and have excellent physical properties and low toxicity. Moreover, considering the ongoing environmental impact of noxious chemical waste products, it is important to adopt eco-friendly approaches for nanoparticle synthesis. In this work, a natural polymer (medium molecular weight chitosan) derived from chitin was employed as a reducing agent to obtain gold nanoparticles (AuNPs) with a chitosan shell (AuNPs@CS) by a microwave oven. The chitosan is economically viable and cost-competitive in the market showing also nontoxic behavior in the environment and living organisms. The synthesized AuNPs@CS-FITC NPs were fully characterized by spectroscopic and microscopic characterization techniques. The size distribution of NPs was about 15 nm, which is a suitable dimension to use in biomedical applications due to their high tissue penetration, great circulation in blood, and optimal clearance as well as low toxicity. The prepared polymer-capped NPs were further functionalized with a fluorescent molecule, i.e., Fluorescein-5-isothiocyanate (FITC), to perform imaging in the cell. The results highlighted the goodness of the synthesis procedure, as well as the high internalization rate that resulted in an optimal fluorescence intensity. Thus, this work presents a good sustainable/green approach-mediated polymer nanocomposite for various applications in the field of diagnostic imaging.
      Citation: Clean Technologies
      PubDate: 2022-09-30
      DOI: 10.3390/cleantechnol4040058
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 954-971: Real-Driving Emissions of an Aging
           Biogas-Fueled City Bus

    • Authors: Kirsi Spoof-Tuomi, Hans Arvidsson, Olav Nilsson, Seppo Niemi
      First page: 954
      Abstract: Transition to low emission transportation and cleaner cities requires a broad introduction of low- and zero-carbon alternatives to conventional petrol- and diesel-powered vehicles. New-generation gas buses are a cost-effective way to reduce local air pollutants from urban transportation. Moreover, major greenhouse gas (GHG) savings may be achieved using biogas as the power source. The main objective of this research was to investigate CH4 and other gaseous emissions of a biogas-fueled urban bus equipped with a three-way catalyst (TWC) in real-world conditions. The study focused on emissions from a six-year-old gas-powered city bus, supplementing emission data from aging bus fleets. Impaired CH4 oxidation and NOx reduction were observed in the catalyst after its service life of 375,000 km–400,000 km. The main reason for low CH4 and NOx conversion over the TWC was concluded to be the partial deactivation of the catalyst. Another critical issue was the fluctuating air-to-fuel ratio. The results show that the efficiency of exhaust after-treatment systems should be closely monitored over time, as they are exposed to various aging processes under transient driving conditions, leading to increased real-world emissions. However, the well-to-wheels (WTW) analysis showed that an 80% GHG emission benefit could be achieved by switching from diesel to biomethane, giving a strong environmental argument for biogas use.
      Citation: Clean Technologies
      PubDate: 2022-10-02
      DOI: 10.3390/cleantechnol4040059
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 972-986: Impact of Battery Energy System
           Integration in Frequency Control of an Electrical Grid with Wind Power

    • Authors: Anukriti Pokhriyal, José Luis Domínguez-García, Pedro Gómez-Romero
      First page: 972
      Abstract: The rapid increase in the integration of renewable energy sources into the electrical grid is posing new challenges for the dynamic responses due to the global inertia reduction. In this regard, the impact on frequency stability of such reduction and the potential support from wind power have been investigated lately. However, it is well-known that the variability of wind power and its reduced inertia may not be enough to handle the power unbalance. Energy storage systems (e.g., batteries) may provide the required additional flexibility to ensure proper response. In this paper, an analysis of how the different control loops for frequency support on wind power and batteries interact and perform is presented. To gain insights from the different impacts, a sensitivity analysis comparison for frequency regulation through (i) inertia and droop control of a variable speed wind turbine and (ii) battery is performed. The analysis was carried out through simulations using the well-known 4 generator 2-area model adapted to include a wind farm. From a battery perspective, its ramping capabilities were varied to provide frequency regulation. The paper shows how, depending on the control parameters and battery size, the frequency response may even become unstable due to interactions of the various pieces of technology. Thus, it shows that coordinated actions, control optimization and grid status among different actors on the grid (as battery and wind) is required for stable operation.
      Citation: Clean Technologies
      PubDate: 2022-10-09
      DOI: 10.3390/cleantechnol4040060
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 987-1000: Advanced Electric Battery Power
           Storage for Motors through the Use of Differential Gears and High Torque
           for Recirculating Power Generation

    • Authors: Wenich Vattanapuripakorn, Sathapon Sonsupap, Khomson Khannam, Natthakrit Bamrungwong, Prachakon Kaewkhiaw, Jiradanai Sarasamkan, Bopit Bubphachot
      First page: 987
      Abstract: Electricity has become one of the most important factors contributing to both the livelihoods of individuals and global economic development. Most electricity generation is still derived from burning fossil fuels that contribute to environmental degradation. The aim of this research, through innovative design, was to create clean circular technology through the utilization of electronic devices that control and send optimally timed commands to two 72-volt batteries (DC) that store and distribute energy. This new form of electric power generation was adapted to be used with a three-way differential gear system. The speed of transmission was adjusted, and shaft rotation was connected to a 7.5 kw/h DC power motor with two 15 kw/h alternators in three phases to generate high torque power at the desired rate of 3000 RPM and electricity. The first set of alternators generated the electrical energy to be distributed. The circuit system of battery set one was used for storage and slowly fed to the motor, which was kept continuously running for hours. The second alternator distributed the generated voltage to the secondary battery, which stored backup power and provided the main power to the grid. This system is especially appealing for those looking to improve energy efficiency and contribute to the green economy, as this system can be applied to power charging stations for electric vehicles or used as a backup power source for buildings.
      Citation: Clean Technologies
      PubDate: 2022-10-11
      DOI: 10.3390/cleantechnol4040061
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1001-1019: Acid Gas Re-Injection System
           Design Using Machine Learning

    • Authors: Vassiliki Anastasiadou, Anna Samnioti, Renata Kanakaki, Vassilis Gaganis
      First page: 1001
      Abstract: An “energy evolution” is necessary to manifest an environmentally sustainable world while meeting global energy requirements, with natural gas being the most suitable transition fuel. Covering the ever-increasing demand requires exploiting lower value sour gas accumulations, which involves an acid gas treatment issue due to the greenhouse gas nature and toxicity of its constituents. Successful design of the process requires avoiding the formation of acid gas vapor which, in turn, requires time-consuming and complex phase behavior calculations to be repeated over the whole operating range. In this work, we propose classification models from the Machine Learning field, able to rapidly identify the problematic vapor/liquid encounters, as a tool to accelerate phase behavior calculations. To set up this model, a big number of acid gas instances are generated by perturbing pressure, temperature, and acid gas composition and offline solving the stability problem. The generated data are introduced to various classification models, selected based on their ability to provide rapid answers when trained. Results show that by integrating the resulting trained model into the gas reinjection process simulator, the simulation process is substantially accelerated, indicating that the proposed methodology can be readily utilized in all kinds of acid gas flow simulations.
      Citation: Clean Technologies
      PubDate: 2022-10-13
      DOI: 10.3390/cleantechnol4040062
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1020-1053: The Combined Implementation of
           Electrocoagulation and Adsorption Processes for the Treatment of
           Wastewaters

    • Authors: Nuno S. Graça, Alírio E. Rodrigues
      First page: 1020
      Abstract: Effluent treatment and reuse are essential in order to address the global problem of water scarcity. Additionally, improving the quality of treated wastewater is necessary to reduce its adverse effects on natural water resources and, consequently, on human health. Electrocoagulation and adsorption have been successfully applied separately to treat different wastewaters. Each method has unique benefits, drawbacks, and parameters that affect the effectiveness of treatment. A review of both processes, including their theoretical principles, the effect of operating conditions, and practical applications, is presented to provide an overview of their capabilities. The combination of electrocoagulation and adsorption in a combined process can be used to amplify the advantages of each process while mitigating their limitations. In the present work, the combined process is analyzed in terms of its principles, applications, and integration in a circular economy model.
      Citation: Clean Technologies
      PubDate: 2022-10-14
      DOI: 10.3390/cleantechnol4040063
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1054-1070: Cost–Benefit Analysis of
           Kaposvár Solar Photovoltaic Park Considering Agrivoltaic Systems

    • Authors: Aidana Chalgynbayeva, Tamás Mizik, Attila Bai
      First page: 1054
      Abstract: In the context of the global energy crisis and crucial issues on food, the development and utilization of agrivoltaic (APV) systems could be a way to solve both the energy shortage and agricultural production at the same time and in the same area. As a combination of photovoltaics (PV) and agriculture, agrivoltaics has broad prospects for the future agricultural development of Hungary. Since especially large-scale PV systems can be considered as a potential basis of APV systems, the Kaposvár Solar Power Plant Project in Hungary was analyzed in this study. Two comparative analyses were used: between APV and PV systems, and between APV and apple plantation. An economic model has been developed. The baseline scenario shows that APV systems in current technological and economic conditions are not competitive with PV systems and are also less attractive for agricultural farmers, due to the long return period of the surplus investment cost. By analyzing uncertain factors and seeking possible solutions, the authors’ recommendations for the development, subsidy system and technology might be useful for both farmers and for decision makers to promote APV systems in the future.
      Citation: Clean Technologies
      PubDate: 2022-10-14
      DOI: 10.3390/cleantechnol4040064
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1071-1087: Thermal- and MnO2-Activated
           Peroxydisulfate for Diuron Removal from Water

    • Authors: Angelo Fenti, Antonio Minò, Stefano Salvestrini
      First page: 1071
      Abstract: In this work, a peroxydisulfate (PDS)-based advanced oxidation process was used for removing diuron from water. The effect of heat and MnO2 as PDS activators was explored. It was found that diuron degradation obeyed zero-order kinetics in the presence of heat-activated PDS. The relative contribution of MnO2 to the diuron degradation decreased with the increasing temperature. At the highest temperature investigated, T = 55 °C, complete diuron removal was achieved in less than 75 min. A kinetic model for describing the rate of diuron degradation was proposed and successfully applied to the experimental data.
      Citation: Clean Technologies
      PubDate: 2022-10-19
      DOI: 10.3390/cleantechnol4040065
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1088-1102: Water Pollution and Agriculture
           Pesticide

    • Authors: Samira Mosalaei Rad, Ajay K. Ray, Shahzad Barghi
      First page: 1088
      Abstract: The agricultural industry uses substantial amounts of water (the highest in the world) mostly for irrigation purposes. Rapid population growth and, consequently, growing demand for food have increased the use of pesticide to have higher yield for crops and other agricultural products. Wastewater generated as a result of excessive use of pesticides/herbicides in agricultural industry is becoming a global issue specifically in developing countries. Over 4,000,000 tons of pesticides are currently used in the world annually and high concentrations above their threshold limits have been detected in water bodies worldwide. The generated wastewater (contaminated with pesticides) has negative impacts on human health, the ecosystem, and the aquatic environment. Recently, biodegradable and biocompatible (including plant-based) pesticides have been introduced as green and safe products to reduce/eliminate the negative impacts of synthetic pesticides. Despite positive advantages of biopesticides, their use is limited due to cost and slow interaction with pests compared to chemical pesticides. Pesticides may also react with water and constituents of soil resulting in formation of intermediates having different physical and chemical properties. Diffusion, dispersion, and permeation are main mechanisms for transfer of pesticides in soil and water. Pesticides may degrade naturally in nature; however, the time requirement can be very long. Many mathematical models have been developed to simulate and estimate the final fate of pesticides in water resources. Development of new technologies and environmentally friendly pesticides to reduce water contamination is becoming increasingly important.
      Citation: Clean Technologies
      PubDate: 2022-10-20
      DOI: 10.3390/cleantechnol4040066
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1103-1126: Effects of MgO and Fe2O3 Addition
           for Upgrading the Refractory Characteristics of Magnesite Ore Mining
           Waste/By-Products

    • Authors: Evangelia Pagona, Kyriaki Kalaitzidou, Vasileios Zaspalis, Anastasios Zouboulis, Manassis Mitrakas
      First page: 1103
      Abstract: In the context of a circular economy/zero-waste, the conversion of extractive wastes into new products is of particular importance. At the Grecian Magnesite SA mine (Chalkidiki, N. Greece), millions of tons of waste accumulate in the operation field. To achieve these goals, the effect of caustic calcined magnesia (MgO) at 10, 15, and 20 wt.% was investigated in combination with 0.5, 1, 2.5, and 5 wt.% Fe2O3 at 1300 °C and 1600 °C for 120 min. The main refractory properties were determined along with the mineralogical content. The morphological examination has been performed by SEM-EDS analysis. The addition of MgO increases the desired olivine and eliminates the unwanted pyroxenes, causing the formation of magnesium-ferrite and periclase. MgO wt.% addition resulted in the decrease of firing shrinkage at 1300 °C but increased with Fe2O3. At 1600 °C, firing shrinkage had a minimum value at the optimum MgO dose. Mechanical strength at 1600 °C achieved a maximum value at the optimum MgO dose plus 5 wt.% MgO and 2.5 wt.% Fe2O3 due to sintering process/magnesioferrite formation. These results indicate that MgO and Fe2O3 upgrade the refractoriness of magnesite mining wastes due to the diffusion of Fe2O3 in MgO excess.
      Citation: Clean Technologies
      PubDate: 2022-10-31
      DOI: 10.3390/cleantechnol4040067
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1127-1137: Thermochemical Conversion of
           Sugarcane Bagasse: A Comprehensive Analysis of Ignition and Burnout
           Temperatures

    • Authors: Leandro C. de Morais, Amanda A. Maia, Pedro R. Resende, André H. Rosa, Leonel J. R. Nunes
      First page: 1127
      Abstract: The Brazilian sugarcane industry generates a significant amount of waste each year, which should be properly analyzed and studied to allow an adequate recovery and application supported by the best understanding of its properties. The present work reports the ignition and burnout temperatures of sugarcane bagasse (SCB) obtained after performing a thermal analysis using four different heating rates. The intersection method (IM) and deviation method (DM) were employed to approach the ignition and burnout temperatures of the sugarcane bagasse. The ignition temperatures of the SCB measured from IM are between 250 and 263 °C, and their burnout temperatures are between 357 and 377 °C. The ignition temperature was in the range of 205 °C to 236 °C for the DM. IM is recommended for determining the ignition and burnout temperatures. In TGA, the heating rates in the range of 10 °C·min−1 and 15 °C·min−1 are suggested due to their accuracy and the contribution to timesaving in the analysis.
      Citation: Clean Technologies
      PubDate: 2022-11-01
      DOI: 10.3390/cleantechnol4040068
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1138-1151: Solid Waste Management in Rural
           Communities of Developing Countries: An Overview of Challenges and
           Opportunities

    • Authors: Giovanni Vinti, Mentore Vaccari
      First page: 1138
      Abstract: Solid waste management (SWM) in rural areas of many low- and middle-income countries (LMICs) represents a critical and underrated topic. However, almost half of the world’s population still lives in rural areas and an adequate SWM is crucial in reducing environmental and health threats. A lack of knowledge and appropriate tools often leads to inappropriate practices such as waste dumping and uncontrolled burning. However, appropriate methods can transform waste into resources and even guarantee a revenue source. This manuscript provides an overview of the state of the knowledge characterising SWM in rural communities of LMICs, analysing common practices and principal issues. Different solid waste fractions are considered. Virtuous approaches are presented, taking into account recent sustainable solutions. Considering that a relevant part of the world population is still living in rural areas, the benefits associated with an appropriate SWM may be enormous. Such activities may improve local conditions from social, environmental and health perspectives; furthermore, they may have a global impact on facing climate change and environmental pollution.
      Citation: Clean Technologies
      PubDate: 2022-11-02
      DOI: 10.3390/cleantechnol4040069
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1152-1161: Adsorption Cooler Design, Dynamic
           Modeling, and Performance Analyses

    • Authors: João M. S. Dias, Vítor A. F. Costa
      First page: 1152
      Abstract: This paper presents an adsorption cooler (AC) driven by the surplus heat of a solar thermal domestic hot water system to provide cooling to residential buildings. A cylindrical tube adsorber using granular silica gel as adsorbent and water as adsorbate was considered. The AC was modelled using a two-dimensional distributed parameter model implemented in previous adsorption heating and cooling studies. The performance coefficients of the resultant thermally driven cooling system were obtained for a broad range of working conditions. The thermally driven AC was found to have coefficient of performance (COP) of 0.5 and a specific cooling power (SCP) of 44 W·kg−1 when considering condenser, evaporator, and regeneration temperatures of 30 °C, 15 °C, and 70 °C, respectively. Moreover, the results showed that the AC could be used for refrigeration purposes at temperatures as low as 2 °C and that it could also operate during hotter days under temperatures of 42 °C.
      Citation: Clean Technologies
      PubDate: 2022-11-03
      DOI: 10.3390/cleantechnol4040070
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1162-1174: End-of-Life Management of
           Electric Vehicle Lithium-Ion Batteries in the United States

    • Authors: Jay N. Meegoda, Sarvagna Malladi, Isabel C. Zayas
      First page: 1162
      Abstract: Electric vehicles, which are primarily powered by lithium-ion batteries, have gained much attention as the future of transportation for their environmental and economic benefits. However, the current economy of lithium-ion battery management is quite linear. A circular economy with reusing and end-of-life recycling of lithium-ion batteries, would reduce the social and environmental costs associated with the mining of metals, decelerate the depletion of natural resources, and prevent the improper management that often accompanies disposal. This research suggests improvements to the end-of-life management of lithium-ion batteries in the US, considering current and emerging recycling technologies, current collection and transportation infrastructure, current reuse applications, and an analysis of the current regulatory policies in place. Along with providing a comprehensive overview of these topics, this research compiles and provides a set of actionable End-of-Life (EOL) management recommendations for the US on policy, infrastructure, and technology.
      Citation: Clean Technologies
      PubDate: 2022-11-14
      DOI: 10.3390/cleantechnol4040071
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1175-1192: Steam Explosion Pre-Treatment of
           Sawdust for Biofuel Pellets

    • Authors: Peyman Alizadeh, Tim Dumonceaux, Lope G. Tabil, Edmund Mupondwa, Majid Soleimani, Duncan Cree
      First page: 1175
      Abstract: The current study explores steam explosion pre-treatment of wood sawdust to develop high-quality biofuel pellets. In order to determine optimized conditions (temperature and residence time) for steam-treated biomass, seven test responses were chosen, including bulk, particle and pellet densities as well as tensile strength, dimensional stability, ash content and higher heating value (HHV). Parameters tested for steam treatment process included the combination of temperatures 180, 200 and 220 °C and durations of 3, 6 and 9 min. Results showed that when the severity of steam pre-treatment increased from 2.83 to 4.49, most of the qualities except HHV and ash content were favorable for steam pretreated materials. The pellet density of pretreated sawdust in comparison to raw sawdust resulted in 20% improvement (1262 kg/m3 for pretreated material compared with 1049 kg/m3 for non-treated material). Another important factor in determining the best pellet quality is tensile strength, which can be as high as 5.59 MPa for pretreated pellets compared with 0.32 MPa for non-treated pellets. As a result, transportation and handling properties can be enhanced for steam pretreated biomass pellets. After optimization, the selected treatment was analyzed for elemental and chemical composition. Lower nitrogen and sulfur contents compared with fossil fuels make steam pretreated pellets a cleaner option for home furnaces and industrial boilers. High-quality pellets were produced based on optimized pre-treatment conditions and are therefore suggested for bioenergy applications.
      Citation: Clean Technologies
      PubDate: 2022-11-15
      DOI: 10.3390/cleantechnol4040072
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1193-1207: Advances in Carbon Capture and
           Use (CCU) Technologies: A Comprehensive Review and CO2 Mitigation
           Potential Analysis

    • Authors: Christiano B. Peres, Pedro M. R. Resende, Leonel J. R. Nunes, Leandro C. de Morais
      First page: 1193
      Abstract: One of society’s major current challenges is carbon dioxide emissions and their consequences. In this context, new technologies for carbon dioxide (CO2) capture have attracted much attention. One of these is carbon capture and utilization (CCU). This work focuses on the latest trends in a holistic approach to carbon dioxide capture and utilization. Absorption, adsorption, membranes, and chemical looping are considered for CO2 capture. Each CO2 capture technology is described, and its benefits and drawbacks are discussed. For the use of carbon dioxide, various possible applications of CCU are described, starting with the utilization of carbon dioxide in agriculture and proceeding to the conversion of CO2 into fuels (catalytic processes), chemicals (photocatalytic processes), polymers, and building supplies. For decades, carbon dioxide has been used in industrial processes, such as CO2-enhanced oil recovery, the food industry, organic compound production (such as urea), water treatment, and, therefore, the production of flame retardants and coolants. There also are several new CO2-utilization technologies at various stages of development and exploitation, such as electrochemical conversion to fuels, CO2-enhanced oil recovery, and supercritical CO2. At the end of this review, future opportunities are discussed regarding machine learning (ML) and life cycle assessment (LCA).
      Citation: Clean Technologies
      PubDate: 2022-11-17
      DOI: 10.3390/cleantechnol4040073
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1208-1226: Evaluation of the Use of
           Different Dedicated Mechanical Subcooling (DMS) Strategies in a Water
           Source Transcritical CO2 Heat Pump for Space Heating Applications

    • Authors: Fernando Illán-Gómez, José Ramón García-Cascales, Francisco Javier Sánchez-Velasco, Ramón A. Otón-Martínez
      First page: 1208
      Abstract: In this work we analyze numerically different design configurations to be used in a R1234yf DMS cycle coupled with a water source, transcritical CO2 heat pump for heating applications in the building sector. Specifically, we study the temperature range proposed by a European standard for heating with inlet/outlet water temperatures of: 30 °C/35 °C, 40 °C/45 °C, 47 °C/55 °C and 55 °C/65 °C. Moreover, 25 °C/30 °C is also analyzed which is the range expected for indoor swimming pool water pool heating applications. A water inlet temperature of 10 °C at the evaporator was considered in all of the cases. Results show that depending on the coupling strategy between the DMS cycle and the CO2 heat pump, optimal COP values obtained can vary up to 30% whereas the optimal operating pressure of the CO2 cycle can vary up to 8%. A configuration based on splitting the water flow to be heated into the DMS condenser and the gas cooler in a system with IHX was the best option for all the temperature ranges studied. The improvement in the maximum COP values obtained with this configuration ranges between 5% (for swimming pool applications) and 25% (for space heating with 40 °C/45 °C) when compared with the base cycle depending on the water temperature range considered. When this configuration is not considered, the basic transcritical CO2 with IHX and without DMS was found the best option.
      Citation: Clean Technologies
      PubDate: 2022-11-17
      DOI: 10.3390/cleantechnol4040074
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1227-1241: Data-Driven Machine Learning
           Approach for Predicting the Higher Heating Value of Different Biomass
           Classes

    • Authors: Inioluwa Christianah Afolabi, Emmanuel I. Epelle, Burcu Gunes, Fatih Güleç, Jude A. Okolie
      First page: 1227
      Abstract: Higher heating values (HHV) is a very useful parameter for assessing the design and large-scale operation of biomass-driven energy systems. HHV is conventionally measured experimentally with an adiabatic oxygen bomb calorimeter. This procedure is often time-consuming and expensive. Furthermore, limited access to the required facilities is the main bottleneck for researchers. Empirical linear and nonlinear models have initially been proposed to address these concerns. However, most of the models showed discrepancies with experimental results. Data-driven machine learning (ML) methods have also been adopted for HHV predictions due to their suitability for nonlinear problems. However, most ML correlations are based on proximate or ultimate analysis. In addition, the models are only applicable to either the originator biomass or one specific type. To address these shortcomings, a total of 227 biomass datasets based on four classes of biomass, including agricultural residue, industrial waste, energy crop, and woody biomass, were employed to develop and verify three different ML models, namely artificial neural network (ANN), decision tree (DT) and random forest (RF). The model incorporates proximate and ultimate analysis data and biomass as input features. RF model is identified as the most reliable because of its lowest mean absolute error (MAE) of 1.01 and mean squared error (MSE) of 1.87. The study findings can be used to predict HHV accurately without performing experiments.
      Citation: Clean Technologies
      PubDate: 2022-11-22
      DOI: 10.3390/cleantechnol4040075
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1242-1254: Optimal Placement of Distributed
           Generation Based on Power Quality Improvement Using Self-Adaptive
           Lévy Flight Jaya Algorithm

    • Authors: Gubbala Venkata Naga Lakshmi, Askani Jaya Laxmi, Venkataramana Veeramsetty, Surender Reddy Salkuti
      First page: 1242
      Abstract: The optimal placement of distributed generation (DG) is a critical task for distribution companies in order to keep the distribution network running smoothly. The optimal placement of DG units is an optimization problem. In this paper, minimization of the voltage deviation from flat voltage is considered as an objective function. The self-adaptive Lévy flight-based Jaya algorithm is used as an optimization technique to determine the best location and size of distributed generation units. In the MATLAB environment, the proposed algorithm was implemented on IEEE 15 and PG and E 69 bus distribution systems. According to the simulation results, distribution networks can supply more quality power to customers by minimizing the voltage deviation from the flat voltage profile if the DG units are properly placed and sized.
      Citation: Clean Technologies
      PubDate: 2022-11-28
      DOI: 10.3390/cleantechnol4040076
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1255-1268: Potential of Released Essential
           Oils from Active Packaging to Reduce Refrigeration Needs of Fruit and
           Vegetables

    • Authors: Ginés Benito Martínez-Hernández, Antonio López-Gómez
      First page: 1255
      Abstract: The energy efficiency of fruit and vegetables refrigeration facilities can be increased through the reduction of heat generated by produce (in kWh/kg). Ethylene production in fruit and vegetables is closely linked to their respiration rates. Clean technologies that can reduce ethylene production of fruit and vegetables are needed to relax (increase) the setpoint temperature of cold rooms. The heat produced may be reduced by up to 50% when ethylene concentrations surrounding the produce are reduced from 0.1–1 to 0.001–0.01 μL L−1 during the storage of some vegetables. There is a need to find green alternatives to ethylene scavenging techniques (of high cost and chemical origin) such as, for example, active packaging with encapsulated essential oils. Hence, respiration and ethylene production rates of flat peaches and broccoli were reduced by up to 30–50% with active packaging with essential oils. It would imply a lower produce heat generation of 14–30% with the consequent energy savings in the refrigeration systems of horticultural facilities. Consequently, the potential of essential oils released from active packaging to reduce the energy consumption related to respiratory heat of produce is hereby firstly reviewed and proposed as a clean technology to extend the postharvest life of fruit and vegetables.
      Citation: Clean Technologies
      PubDate: 2022-12-01
      DOI: 10.3390/cleantechnol4040077
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1269-1289: A Comparison of the Use of
           Pontryagin’s Maximum Principle and Reinforcement Learning Techniques
           for the Optimal Charging of Lithium-Ion Batteries

    • Authors: Andreas Rauh, Marit Lahme, Oussama Benzinane
      First page: 1269
      Abstract: Battery systems are one of the most important components for the development of flexible energy storage for future applications. These comprise energy storage in both the mobility sector and stationary applications. To ensure the safe operation of multiple battery cells connected in series and parallel in a battery pack, it is essential to implement state of charge (SOC) equalization strategies. Generally, two fundamentally different approaches can be distinguished. On the one hand, these are passive approaches for SOC equalization that are based on including additional Ohmic resistors in a battery back over which equalization currents flow as long as the correspondingly connected cells have different voltages. Despite the simple implementation of such equalization circuits, they have a major drawback, namely wasting stored energy to perform the SOC equalization. This waste of energy goes along with Ohmic heat production, which leads to the necessity of additional cooling for batteries with large power densities. On the other hand, active SOC equalization approaches have been investigated, which allow for an independent charging of the individual cells. Especially, this latter approach has big potential to be more energy efficient. In addition, the potential for a reduction of Ohmic heat production may contribute to extending the lifetime of battery cells. To perform the individual charging of battery cells in an energetically optimal manner, this paper provides a comparison of closed-form optimization approaches on the basis of Pontryagin’s maximum principle and approaches for reinforcement learning. Especially, their accuracy and applicability for the implementation of optimal online cell charging strategies are investigated.
      Citation: Clean Technologies
      PubDate: 2022-12-07
      DOI: 10.3390/cleantechnol4040078
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1290-1299: Dimensioning of the Clearance as
           a Means of Avoiding Burr and Film Formation during the Punching of PC/ABS
           Cable Ducts

    • Authors: Sebastian F. Noller, Roland Heiler, Anja Pfennig
      First page: 1290
      Abstract: The production of staple articles such as cable ducts offers reductions in resource and production energy consumption if the process is optimized. Side recesses made of polyvinyl chloride (PVC) have already been punched successfully as one of the process steps during the production of cable ducts. However, punching cable ducts made of flame-retardant polycarbonate/acrylonitrile–butadiene–styrene (PC/ABS) is challenging because increased burr and film formation occurs. This study introduces the correct dimensioning of the clearance as a means of reducing the burr and film formation and presents the ideal clearance dimensions. This new process design approach comprises the dimensioning of the clearance and its subsequent successful application. Tools with clearances in the relevant size range were purchased and examined by means of punching tests. The punch-outs were evaluated regarding the quality characteristics, such as the burr, film, cut surface quality, shear droop, and plastic flow characteristics. Excerpts from high-speed recordings were used to assess the punch-outs qualitatively. The burr formation is significantly decreased by the use of a correctly dimensioned clearance, allowing for the crack initiated at the punch side and the crack initiated at the die side to meet perfectly. It is assumed that film formation can be avoided via a significant reduction in the friction or heat input during the punching process.
      Citation: Clean Technologies
      PubDate: 2022-12-14
      DOI: 10.3390/cleantechnol4040079
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1300-1316: Evaluation of Commercial Reverse
           Osmosis and Nanofiltration Membranes for the Removal of Heavy Metals from
           Surface Water in the Democratic Republic of Congo

    • Authors: Vercus Lumami Kapepula, Mar García Alvarez, Vida Sang Sefidi, Estella Buleng Njoyim Tamungang, Théophile Ndikumana, Dieu-Donné Musibono, Bart Van Der Bruggen, Patricia Luis
      First page: 1300
      Abstract: This study evaluates the performance of commercial reverse osmosis (RO) and nanofiltration (NF) membranes for the removal of metal ions from synthetic water and surface water carried from the north-west of Lake Tanganyika in the city of Uvira, in the east of the Democratic Republic of Congo. Metal ion analyses were performed by the standardized ICP-MS and ICP-OES methods. The RO membrane showed higher metal ion rejection in high-concentration solutions (synthetic samples) prepared in the laboratory as well as in low-concentration samples from real raw water collected near Lake Tanganyika. Rejection levels were higher than 98% for Cr3+, Pb2+, Cd2+, As3+, Ni2+, and Sb+3 ions in the synthetic solutions, and 99.2, 98.8, 98.6, 99.2, 98.4, and 98.8%, respectively, in the real samples. The concentrations of metals in the permeate varied depending on the feed concentration and were 0.15 to 1.02 mg/L, 0.33 to 22 mg/L, and 0.11 to 22 mg/L in RO, NF90, and NF270 membranes, respectively. Regarding the NF membranes, the rejection of Cr, Ni, and Cd ions was interesting: 98.2, 97.8, and 92.3%, respectively. However, it was lower for Pb, As, and Sb ions: 76.9, 52.5 and 64.1%, respectively. The flux of NF was 329 to 375 L/m2.h, much higher than for RO membranes, which had a flux of 98 to 132 L/m2.h. The studied membranes are thus a feasible solution to remove the studied metals from real water sources at low concentrations since they meet the standards of the World Health Organization on specific values assigned to chemicals from industrial sources and human habitation areas where these ions are present in drinking water.
      Citation: Clean Technologies
      PubDate: 2022-12-14
      DOI: 10.3390/cleantechnol4040080
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 1317-1329: Temperature-Dependent
           Structure–Function Properties of Bacterial Xylose Isomerase Enzyme
           for Food Applications: An In Silico Study

    • Authors: Maurya Sharma, Naayaa Mehta, Renuka Suravajhala, Cynthia Meza, Shrabana Sarkar, Aparna Banerjee
      First page: 1317
      Abstract: Xylose Isomerase (XI) is an intramolecular oxidoreductase enzyme and catalyzes the reversible conversion of ketoses and aldoses in addition to the bioconversion of ethanol from xylose in the production of bioethanol from hemicellulose. It has a broad range of industrial applications in the food and pharmaceutical sectors, particularly in the production of the sweetener high fructose corn syrup (HFCS). It is one of the most widely used industrial enzymes after protease. Taking this into consideration, four bacterial XI sources were selected based on growth temperature, i.e., psychrophile, mesophile, thermophile, and hyperthermophile, for analyzing Xylose Isomerase’s structure-function characteristics. It was found that thermophilic XI was structurally less stable than mesophilic and hyperthermophilic XI, whereas structural plasticity ran opposite towards mesophiles. The interaction of xylose isomerase (XI) with two ligands, namely Amino-2-Hydroxymethyl-Propane-1,3-Diol and (4R)-2-Methylpentane-2,4- Diol, was also studied. Mesophilic XI demonstrated better binding affinity with structurally stabilizing amino acids (Ala, Asp, Gly, Leu, and Arg). In comparison, Thermophilic XI showed nearly similar binding affinity with both Amino-2-Hydroxymethyl-Propane-1,3-Diol and (4R)-2-Methylpentane-2,4-Diol. The results of this investigation suggest that thermophilic XI, followed by mesophilic XI, would be the most appropriate for establishing process stability and sustainability in the food industry.
      Citation: Clean Technologies
      PubDate: 2022-12-14
      DOI: 10.3390/cleantechnol4040081
      Issue No: Vol. 4, No. 4 (2022)
       
  • Clean Technol., Vol. 4, Pages 584-606: Cleaner Technology and Natural
           Resource Management: An Environmental Sustainability Perspective from
           China

    • Authors: Fiza Shaheen, Muhammad Saeed Lodhi, Joanna Rosak-Szyrocka, Khalid Zaman, Usama Awan, Muhammad Asif, Waqas Ahmed, Maria Siddique
      First page: 584
      Abstract: In economies, cleaner technology, increased demand for renewable energy, and more efficient use of natural resources contribute to meeting environmental sustainability targets. The Chinese economy is no exception in its attempts to conserve economic and natural resources via collaborative efforts to embrace cleaner technology, green energy sources, and resource conservation management to preserve resources for future generations. This research examines the influence of cleaner technologies, green energy sources, and natural resource management on reducing greenhouse gas emissions using quarterly data for the Chinese economy from 2000Q1 to 2020Q4. The findings demonstrate that increasing demand for green energy reduces greenhouse gas emissions, hence substantiating the premise of ‘green is clean’ energy development. Additionally, optimum resource usage enhances environmental quality, corroborating the ‘resource cleaner blessing’ hypothesis. The positive link between inward foreign direct investment and greenhouse gas emissions substantiates the ‘pollution haven’ concept, according to which inward foreign direct investment uses unsustainable technology in manufacturing processes, hence degrading air quality indicators. Inadequate access to clean cooking technology and increased population density has a detrimental effect on the country’s environmental sustainability agenda, which must be corrected via sustainable regulations. The causality estimates show the feedback relationship between renewable energy demand (and economic growth) and cleaner technology, between economic growth and green energy (and inbound foreign direct investment), and between population density and economic growth (and green energy). The Impulse Response function estimates suggested that economic growth and population density would likely increase GHG emissions. In contrast, cleaner technology, green energy demand, natural resource management, and inbound foreign direct investment would likely decrease greenhouse gas emissions for the next ten-year time period. The sustainability of the environment and natural resources in China is bolstered by developing cleaner technologies, a greater reliance on renewable energy sources, and better management of natural resources.
      Citation: Clean Technologies
      PubDate: 2022-06-28
      DOI: 10.3390/cleantechnol4030036
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 607-618: State of Charge and Capacity
           Tracking in Vanadium Redox Flow Battery Systems

    • Authors: Kalvin Schofield, Petr Musilek
      First page: 607
      Abstract: The vanadium redox flow battery electrolyte is prone to several capacity loss mechanisms, which must be mitigated to preserve electrolyte health and battery performance. This study investigates a simple and effective technique for the recovery of capacity loss arising from symmetrical mechanisms via automatic electrolyte rebalancing. However, chemical or electrochemical techniques must be used to mitigate capacity loss from asymmetrical mechanisms (e.g., air oxidation of V2+), which requires knowledge of the oxidation states present in the electrolytes. As such, this study assesses the suitability of SOC tracking via electrolyte absorption for independent monitoring of the anolyte and catholyte within an existing VRFB system. Testing is performed over cycling of a 40 cell, 2.5 kW with 40 L of electrolyte. Optical monitoring is performed using a custom-made flow cell with optical paths (interior cavity thicknesses) ranging from 1/4″ to 1/16″. Light transmitted through the cell by a 550 lumen white light source is monitored by a simple photodiode. The electrolyte rebalancing mechanism displayed success in recovering symmetrical capacity losses, while optical monitoring was unsuccessful due to the high absorbance of the electrolyte. Potential improvements to the monitoring system are presented to mitigate this issue.
      Citation: Clean Technologies
      PubDate: 2022-06-28
      DOI: 10.3390/cleantechnol4030037
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 619-628: Defect Properties of Li2NiGe3O8

    • Authors: Navaratnarajah Kuganathan, Raveena Sukumar, Poobalasuntharam Iyngaran
      First page: 619
      Abstract: There is a growing interest in finding a suitable electrolyte material for the construction of rechargeable Li-ion batteries. Li2NiGe3O8 is a material of interest with modest Li-ionic conductivity. The atomistic simulation technique was applied to understand the defect processes and Li-ion diffusion pathways, together with the activation energies and promising dopants on the Li, Ni, and Ge sites. The Li-Ni anti-site defect cluster was found to be the dominant defect in this material, showing the presence of cation mixing, which can influence the properties of this material. Li-ion diffusion pathways were constructed, and it was found that the activation energy for a three-dimensional Li-ion migration pathway is 0.57 eV, which is in good agreement with the values reported in the experiment. The low activation energy indicated that Li-ion conductivity in Li2NiGe3O8 is fast. The isovalent doping of Na, Fe and Si on the Li, Ni and Ge sites is energetically favorable. Both Al and Ga are candidate dopants for the formation of Li-interstitials and oxygen vacancies on the Ge site. While Li-interstitials can improve the capacity of batteries, oxygen vacancies can promote Li-ion diffusion.
      Citation: Clean Technologies
      PubDate: 2022-07-01
      DOI: 10.3390/cleantechnol4030038
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 629-652: Adsorption of Lead from Aqueous
           Solution by Biochar: A Review

    • Authors: Chuanbin Wang, Xutong Wang, Ning Li, Junyu Tao, Beibei Yan, Xiaoqiang Cui, Guanyi Chen
      First page: 629
      Abstract: Industrialization has resulted in the discharge of a certain amount of lead (Pb) from industrial sources causing damage risk to water quality and human health. Adsorption is an effective technique to remove Pb, and biochar has been widely studied owing to its advantages of low cost and high adsorption capacity. This review summarizes the influence of raw materials and modification methods on the adsorption capability of biochar. The adsorption isotherms and kinetics of biochar were summarized, and the main Pb removal mechanisms were studied systematically. In addition, the challenges and future perspectives were discussed comprehensively. It is expected that the review could provide insightful fundamentals for the experimental research and practical applications of biochar.
      Citation: Clean Technologies
      PubDate: 2022-07-08
      DOI: 10.3390/cleantechnol4030039
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 653-668: Thermochemical Conversion Processes
           as a Path for Sustainability of the Tire Industry: Carbon Black Recovery
           Potential in a Circular Economy Approach

    • Authors: Leonel J. R. Nunes, Laura Guimarães, Miguel Oliveira, Peter Kille, Nuno G. C. Ferreira
      First page: 653
      Abstract: The common use of tires is responsible for the production of large quantities of waste worldwide, which are landfilled or energetically recovered, with higher economical cost and known environmentally harmful consequences. This type of problem must be studied, and all efforts must be conducted to eliminate, or at least mitigate, such high costs. The use of thermochemical conversion processes, such as pyrolysis, can allow the recycling and the reuse of raw materials for the tire industry, namely, in the production of carbon black, usually produced using the controlled combustion of fossil fuels. This article reports the production of torrefied and carbonized waste tire samples using a laboratorial procedure, and their subsequent laboratory characterization, specifically the elemental and proximate analysis. This preliminary approach found that carbon concentration in the produced rubber char reached values higher than 75%, indicating the possibility of its reuse in the production of carbon black to in turn be used in the production of new tires or other industrial rubber materials. The possibility of using this rubber char for other uses, such as energy recovery, is still depending on further studies, namely, the evaluation of the amount of sulfur present in the final product.
      Citation: Clean Technologies
      PubDate: 2022-07-12
      DOI: 10.3390/cleantechnol4030040
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 669-689: Drying Kinetics of Macroalgae as a
           Function of Drying Gas Velocity and Material Bulk Density, Including
           Shrinkage

    • Authors: Craig Walker, Madoc Sheehan
      First page: 669
      Abstract: Macroalgae have many potential applications and can make important contributions to sustainability and circular economy objectives. Macroalgae are degradable high-moisture biomaterials and drying is a necessary step, but drying is an energy and capital-intensive part of their production process. This study presents convective drying curves for commercially promising fresh and saltwater species (U. ohnoi and O. intermedium), obtained over a range of industry-relevant drying gas velocities (0.3–2 m/s) and material bulk densities (33–100 kg/m3). Pragmatic diffusion-based drying models that account for the influence of drying gas velocity, material bulk density, and material shrinkage are presented. Results provide critical insights into the validity of diffusion model assumptions for compressible biomaterials and new mechanisms describing gas penetration into such materials are proposed. The drying models provided in this work demonstrate a high degree of accuracy for both species.
      Citation: Clean Technologies
      PubDate: 2022-07-22
      DOI: 10.3390/cleantechnol4030041
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 690-702: Iron and Magnesium Impregnation of
           Avocado Seed Biochar for Aqueous Phosphate Removal

    • Authors: Kang, Parsons, Gunukula, Tran
      First page: 690
      Abstract: There has been increasing interest in using biochar for nutrient removal from water, and its application for anionic nutrient removal such as in phosphate (PO43−) necessitates surface modifications of raw biochar. This study produced avocado seed biochar (AB), impregnated Fe- or Mg-(hydr)oxide onto biochar (post-pyrolysis), and tested their performance for aqueous phosphate removal. The Fe- or Mg-loaded biochar was prepared in either high (1:8 of biochar to metal salt in terms of mass ratio) or low (1:2) loading rates via the co-precipitation method. A total of 5 biochar materials (unmodified AB, AB + High Fe, AB + Low Fe, AB + High Mg, and AB + Low Mg) were characterized according to their selected physicochemical properties, and their phosphate adsorption performance was tested through pH effect and adsorption isotherm experiments. Fe-loaded AB contained Fe3O4, while Mg-loaded AB contained Mg(OH)2. The metal (hydr)oxide inclusion was higher in Fe-loaded AB. Mg-loaded AB showed a unique free O–H functional group, while Fe-loaded AB showed an increase in its specific surface area more than 10-times compared to unmodified AB (1.8 m2 g−1). The effect of the initial pH on phosphate adsorption was not consistent between Fe-(anion adsorption envelope) vs. Mg-loaded AB. The phosphate adsorption capacity was higher with Fe-loaded AB in low concentration ranges (≤50 mg L−1), while Mg-loaded AB outperformed Fe-loaded AB in high concentration ranges (75–500 mg L−1). The phosphate adsorption isotherm by Fe-loaded AB fit well with the Langmuir model (R2 = 0.91–0.96), indicating the adsorptive surfaces were relatively homogeneous. Mg-loaded biochar, however, fit much better with Freundlich model (R2 = 0.94–0.96), indicating the presence of heterogenous adsorptive surfaces. No substantial benefit of high loading rates in metal impregnation was found for phosphate adsorption. The enhanced phosphate removal by Mg-loaded biochar in high concentration ranges highlights the important role of the chemical precipitation of phosphate associated with dissolved Mg2+.
      Citation: Clean Technologies
      PubDate: 2022-07-22
      DOI: 10.3390/cleantechnol4030042
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 703-713: A Simplified Model for Estimating
           Household Air Pollution in Challenging Contexts: A Case Study from Ghana

    • Authors: Giovanni Vinti, Mentore Vaccari
      First page: 703
      Abstract: Almost three billion people rely primarily on inefficient and polluting cooking systems worldwide. Household air pollution is a direct consequence of this practice, and it is annually associated with millions of premature deaths and diseases, mainly in low- and lower-middle-income countries. The use of improved cookstoves often represents an appropriate solution to reduce such health risks. However, in the distribution of such units, it can be necessary to prioritize the beneficiaries. Thus, in this study, we conducted field research involving five rural villages in the Northern part of Ghana, where using three-stone fires or rural stoves was common. Concentrations of PM2.5, PM10, and carbon monoxide (CO) were measured indoors and outdoors. Considering each field mission lasted less than 24 h, assumptions were made so as to calculate the average pollutant concentrations in 24 h through a new, simplified equation that combined efficiency and cost-savings by shortening field assessments. The obtained values were compared with international guidelines. The results showed that PM2.5 and PM10 limits were overstepped in two villages, which should thus be prioritized. However, further research will be necessary to strengthen and validate our proposed equation, which must be seen as a starting point.
      Citation: Clean Technologies
      PubDate: 2022-07-25
      DOI: 10.3390/cleantechnol4030043
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 714-732: Enhancement of Chiller Performance
           by Water Distribution on the Adiabatic Cooling Pad’s Mesh Surface

    • Authors: Anatolijs Borodinecs, Kristina Lebedeva, Natalja Sidenko, Aleksejs Prozuments
      First page: 714
      Abstract: Evaporative cooling is widely recognized as an energy efficient and environmentally-friendly air conditioning solution, and it has drawn a lot of market interest in recent years. However, this technology is accompanied by several challenges. For instance, insufficient evaporation due to poor and non-homogenous water distribution of the pre-cooling pad significantly reduces the cooling performance. The aim of the study is to develop a technique for numerical simulation of the distribution of a droplet liquid (water) on the mesh surface of an adiabatic cooler to improve the performance of air conditioning equipment. Modern computer-aided design (CAD)/computational fluid dynamics (CFD) programs were used to solve the issue. For the mathematical modelling of the medium motion, non-stationary Navier–Stokes equations were used. Parameters such as heat, mass transfer, and the efficiency of liquid droplet spraying were determined. The current study presents CAD modelling, conducted in SolidWorks platform, of water distribution on the adiabatic cooling pad’s mesh surface for improving air conditioning equipment performance. This study provides the methodology for computer modeling and numerical calculation of the parameters of adiabatic cooling, such as modelling of water atomization process. The results show that the use of additional metal mesh intended as cooling pads increases the mass transfer coefficient by Sh ≈ 15–40%; heat transfer coefficient Nu increases by ≈20–40%; and the atomization efficiency increases by ≈30–40%. The installation of metal pad mesh allows for equalized uniformity of the water distribution. The results imply that there are more opportunities to optimize the parameters of adiabatic cooling, which should be evaluated in further research on the subject.
      Citation: Clean Technologies
      PubDate: 2022-07-26
      DOI: 10.3390/cleantechnol4030044
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 733-751: Effect of Various Growth Medium on
           the Physiology and De Novo Lipogenesis of a Freshwater Microalga
           Scenedesmus rotundus-MG910488 under Autotrophic Condition

    • Authors: Rishibha Dixit, Surendra Singh, Manoj Kumar Enamala, Alok Patel
      First page: 733
      Abstract: The microalga Scenedesmus rotundus, isolated from Jabalpur, Madhya Pradesh, India was designated as Scenedesmus rotundus-MG910488 after morphological and molecular identification. In this study, the effects of various autotrophic growth media on the physiology and lipid accumulation of this microalga were investigated. The cell density, amount of photosynthetic pigments, the productivity of biomass and lipid content and the cell morphology of the microalga were shown to be significantly affected by the variation in growth media. The highest biomass of 754.56 ± 14.80 mg L−1 with biomass productivity of 37.73 ± 0.74 mg L−1 day−1 was achieved when this microalgae was cultivated in the Zarrouk’s medium, whereas the highest lipid content of 33.30 ± 1.21% was observed in the BG-11 medium. The results confirm that the BG-11 is a cost-effective and efficient growth medium for this microalga. It also shows that the ingredients of the growth medium and its concentration influence the growth and synthesis of biomolecules produced by microalga. The biodiesel produced from obtained lipids was qualitatively estimated by Gas Chromatography-Mass Spectroscopy (GC-MS), Nuclear Magnetic Resonance (1H, 13C NMR) and Fourier Transform-Infrared Spectroscopy (FT-IR), which indicate the presence of oleic acid methyl ester, linoleic acid methyl ester and palmitic acid methyl ester as the leading fatty acid methyl esters (FAME) in the samples, which make this strain an ideal feedstock for biodiesel production.
      Citation: Clean Technologies
      PubDate: 2022-08-01
      DOI: 10.3390/cleantechnol4030045
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 752-769: Floating Photovoltaics: A Review

    • Authors: Laura Essak, Aritra Ghosh
      First page: 752
      Abstract: The world is transitioning towards a net zero emissions future and solar energy is at the forefront of the transition. The land use requirements to install solar farms present a barrier for the industry as population density increases and land prices rise. Floating photovoltaics (FPV) addresses this issue by installing solar photovoltaics (PV) on bodies of water. Globally, installed FPV is increasing and becoming a viable option for many countries. A 1% coverage of global reservoirs with FPV would have a potential capacity of 404GWp benign power production. There are numerous advantages to FPV compared to ground mounted PV (GPV), which are discussed in this review. The major gap in research is the impact FPV has on water quality and living organisms in the bodies of water. This review paper examines the most recent research around FPV, analyzing the benefits, downfalls, and future. The review provides more insight into FPV in terms of varying water bodies that can be used, system efficiency, global potential, and potential for coupling FPV with other technologies.
      Citation: Clean Technologies
      PubDate: 2022-08-08
      DOI: 10.3390/cleantechnol4030046
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 770-784: Development of a Biochar-Based
           Substrate Added with Nitrogen from a Mining Effluent for the Production of
           Picea mariana Seedlings

    • Authors: Émilie Robert, Flavia Lega Braghiroli
      First page: 770
      Abstract: Ammoniacal nitrogen (N-NH3) is one of the pollutants that has adverse effects on the environment and is present in most effluents generated by mining operations. Therefore, mining companies must manage it to keep it below the regulated discharge criteria to avoid environmental contamination. In this context, the present study aims to valorize N-NH3 in the form of ammonium sulphate ((NH4)2SO4) for the manufacture of biochar pellets used as growth substrates for the production of forest seedlings. The biochar was first produced by fast pyrolysis, at 320 °C, and different recipes of pellets were then prepared to evaluate their hardness, binder type and content, humidity and durability. The optimal granule chosen was composed of biochar, corn starch and canola oil. Six combinations of different compositions were then prepared as substrates for black spruce growth: (1) Peat (P); (2) Peat and bulk biochar (PB); (3) Peat and bulk biochar impregnated with ammonium sulfate (PBAS); (4) Peat and biochar pellets impregnated with water (PBPeW); (5) Peat and biochar pellets impregnated with an ammonium sulfate solution (PBPeAS); (6) Peat, biochar pellets impregnated with ammonium sulfate and perlite (PBPeASPer). The effects of these substrates on the growth of black spruce seedlings, as well as fertilizer leaching, were measured. The results show that seedling biomass is equivalent to the control for the granular treatment, but higher biomass was obtained with bulk biochar (PB). This shows that a quarter of peat could be replaced by biochar to obtain similar or even better results of biomass yield and, consequently, solve part of the supply issue. As to plant nutrition, no tendency was observed for the experiments apart from the higher proportion of Ca in spruce needles. The prepared biochar-based pellet substrate appears to not only be advantageous for spruce production but also for other uses such as golf courses, forestry producers and horticultural nurseries using conventional fertilizers and peat as growing media. In addition, these approaches could help the Abitibi-Témiscamingue region in Québec, Canada to build a local circular economy.
      Citation: Clean Technologies
      PubDate: 2022-08-09
      DOI: 10.3390/cleantechnol4030047
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 785-805: Human Exposure Influence Analysis
           for Wireless Electric Vehicle Battery Charging

    • Authors: Adel El-Shahat, Joshua Danjuma, Almoataz Y. Abdelaziz, Shady H. E. Abdel Aleem
      First page: 785
      Abstract: Wireless charging schemes aim to counter some drawbacks of electric vehicles’ wired charging, such as the fact that it does not encourage mobility, leads to safety issues regarding high voltage cables, power adapters high cost, and has more battery waste by companies. In this paper, a comparative study of wireless power transfer multiple coil geometries is performed to analyze the efficiency, coupling coefficient, mutual inductance, and magnetic flux density production for each geometry. Results show that coil geometry, current excitation, and shielding techniques within the Wireless Electric Vehicle Charging (WEVC) system substantially influence magnetic flux leakage. In addition, the paper proposes an analytical framework for a WEVC scheme via electromagnetic resonance coupling. Safety considerations of the WEVC system, including the effects on humans, are investigated in several scenarios based on the relative location of the human while EV charging is conducted as the leading paper’s goal. The exposure measurements are performed across various radial distances from the coils using 3-D FEA ANSYS Maxwell Software (American technology company, Pennsylvania, United States). The analysis shows that WEVC systems can achieve high power transfer, resulting in increased magnetic flux leakage around the coils. The safe distance for humans and animals during the charging sequence is attained from research results. For instance, in the 120 mm spiral coil, 120 mm square coil, and 600 mm spiral coil operating at 1 A, excitation, the SAR levels are under the threshold of 700 mm away from the coils. For the 600 mm spiral coil excited at 8 A, the SAR levels fall under the threshold at 900 mm away from the coils. When shielding is utilized, the safe distance is improved by up to 350 mm. Considering the regulations of the Non-Ionizing Radiation Protection (ICNIRP) standards, 600 mm is a safe distance away from the coils, and, vertically, anywhere past 300 mm is safe for humans.
      Citation: Clean Technologies
      PubDate: 2022-08-15
      DOI: 10.3390/cleantechnol4030048
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 806-814: Effectiveness of Hydrogen
           Production by Bacteroides vulgatus in Psychrophilic Fermentation of Cattle
           Slurry

    • Authors: Joanna Kazimierowicz, Marcin Dębowski, Marcin Zieliński
      First page: 806
      Abstract: H2 is a low-impact energy carrier, which the EU hydrogen strategy has positioned as a major component of energy policy. Dark fermentation by psychrophilic bacteria is a promising avenue of H2 production, though one that requires further study. The aim of this study was to determine the H2 production performance of a Bacteroides vulgatus strain during fermentation of psychrophilic cattle slurry. The test strain was isolated from an inland water body at a depth of 40 ± 5 m. The experimental fermentation process was run at 15 ± 1 °C and yielded 265.5 ± 31.2 cm3 biogas/g COD removed, including 46.9 ± 2.6 cm3 H2/g COD removed. CO2 was the main constituent of the resultant biogas, at 79.8 ± 1.9%. The gas also contained 17.6 ± 1.4% H2 and 2.3 ± 0.2% CH4. Organic matter removal and nutrient take-up from the feedstock were low. Our findings show that practical applicability of this process is hampered by multiple operational hurdles and its relatively poor performance.
      Citation: Clean Technologies
      PubDate: 2022-08-16
      DOI: 10.3390/cleantechnol4030049
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 815-823: The Role of the Compressor
           Isentropic Efficiency in Non-Intrusive Refrigerant Side Characterization
           of Transcritical CO2 Heat Pump Water Heaters

    • Authors: Francisco B. Lamas, Vítor A. F. Costa
      First page: 815
      Abstract: Characterizing the refrigerant side of heat pump water heaters (HPWHs) can be intrusive and expensive. On the other hand, direct external measurement techniques can be unfeasible, particularly in commercial HPWHs for residential applications. Non-intrusive in situ characterization methods have already been successfully implemented in subcritical heat pumps. They provide the refrigerant mass flowrate and the equipment energy performance, by using contact temperature sensors and electric power meters. Subcritical suction and discharge-specific enthalpies necessary to apply the method can be obtained from the measured temperatures and their corresponding saturation pressures. Nevertheless, this approach does not apply to the transcritical CO2 HPWHs. In the supercritical region, temperature and pressure are independent variables, and an iterative process regarding the compressor isentropic efficiency has to be considered. However, when isentropic efficiency data are not available, an additional procedure is required, using a validated gas cooler model to verify the physical reliability of the numerical solutions. This work aims at presenting base thermodynamic analysis of a novel methodology for non-intrusive refrigerant side characterization of transcritical CO2 HPWHs, exploring the influence of the compressor isentropic efficiency condition.
      Citation: Clean Technologies
      PubDate: 2022-08-17
      DOI: 10.3390/cleantechnol4030050
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 824-840: Improvement of Onsite Wastewater
           Systems Performance: Experimental and Numerical Investigation

    • Authors: Md Sazadul Hasan, Joshua Trapp, Mengistu Geza
      First page: 824
      Abstract: Population growth and the associated increase in the use of Onsite Wastewater Treatment Systems (OWTS) in the Black Hills have been a reason for interest in nitrate contamination within the public water supply over the past few years. The main concern for the Black Hills is the presence of karst formation that all OWTS for wastewater travel faster, limiting the natural attenuation of wastewater contaminants. The treatment performance of common soils in the Black Hills and wood-based media was evaluated using soil column experiments and a numerical model, HYDRUS 2D. Nitrate treatment performances were evaluated using alluvial and cedar soils collected from the Black Hills, sand, woodchips (loose and dense), and biochar. This research investigated hydraulic and reaction parameters through a combination of experimental and inverse modeling approaches. A good agreement was obtained between the measured and model-predicted soil moisture content, with R2 values ranging from 0.57 to 0.99. The model was calibrated using flow data and nitrate concentration data measured from leachate collected at the bottom of the experimental columns. Nitrate removal rates varied from 32.3% to 70%, with the highest removal rate in loose woodchips, followed by dense woodchip and biochar, and the lowest removal rate in alluvial materials. The biochar and loose woodchips removed an additional 20% compared to common soils, attributable to the enhanced denitrification rate due to higher water content and organic content. The use of woodchips and biochar should be implemented in OWTS, where there are known karst formations.
      Citation: Clean Technologies
      PubDate: 2022-08-24
      DOI: 10.3390/cleantechnol4030051
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 841-853: Efficient Management of Sewage
           Sludge from Urban Wastewaters with the Addition of Inorganic Waste: Focus
           on Rheological Properties

    • Authors: Andreia F. Santos, Abel G. M. Ferreira, Margarida J. Quina
      First page: 841
      Abstract: Sewage sludge (SS) from urban wastewater treatment is still an environmental, economic, and social problem. Current SS management is not consensual, and more alternatives are required to recover some valuable compounds, such as nutrients and organic matter. This study investigates the use of green liquor dregs from the pulp and paper industry—GLDs—as an adjuvant of drying, to develop a product for agronomic applications, focusing on the rheological behavior. The rheological properties were assessed for anaerobically digested sludge (ADS). The limit viscosity of raw ADS was about 0.005 Pa·s in the case of 5% TSs (total solids) increasing to 0.51 Pa·s for 20% TSs. From the oscillatory tests, the ideal viscous flow below 10% TSs was observed, whereas a viscoelastic–solid behavior was detected for a higher concentration of TSs. The addition of GLDs to the ADS reduced the consistency index, reducing the shear resistance of the material. Rheological assays showed that GLDs may facilitate sludge handling (e.g., extrusion) from the dewatering unit to the dryer. Overall, the addition of GLDs to ADS showed to be a viable option for drying and subsequent soil application. Reusing both residues promote the transition from a linear to a circular economy in the wastewater treatment sector.
      Citation: Clean Technologies
      PubDate: 2022-09-01
      DOI: 10.3390/cleantechnol4030052
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 854-864: Production and Characterization of
           Biochar from Almond Shells

    • Authors: Hamed M. El Mashad, Abdolhossein Edalati, Ruihong Zhang, Bryan M. Jenkins
      First page: 854
      Abstract: Biomass from specialty crops, including almonds, walnuts, and numerous others, serves as an important resource for energy and materials as agricultural systems evolve towards greater sustainability and circularity in management and operations. Biochar was produced from almond shells in a laboratory furnace at temperatures between 300 and 750 °C for residence times of 30 and 90 min with moisture contents of 5% to 15% wet basis. Response surface methodology was used to optimize the biochar yield. Feedstock and product temperatures were continuously monitored throughout the experiments. In addition, larger batches of biochar were also produced in a fixed-bed pilot-scale pyrolyzer. The yield of biochar was determined as a weight fraction of the amount of oven-dry almond shells used in each experiment. Physical and chemical characteristics of biochars were evaluated. Pyrolysis temperature and time were found to be the significant parameters affecting the biochar yield, with second-order regression models derived to fit yield results. As anticipated, highest biochar yields (65%) were obtained at a pyrolysis temperature of 300 °C and a pyrolysis time of 30 min due to the limited volatilization at this short residence at low temperature affecting torrefaction of the feedstock. The average biochar yield from the fixed-bed pilot-scale experiments was 39.5% and more closely aligned with the fixed carbon from standard proximate analyses. Higher pyrolysis temperatures resulted in higher C:N ratio and pH with the highest C:N ratio of 19:1 and pH of 10.0 obtained at a pyrolysis temperature of 750 °C for 90 min. Particle density increased with the increase of pyrolysis temperature. Results of this study can aid in predicting biochar yields from almond shells under different pyrolysis conditions and determining the amount of biochar required for different applications.
      Citation: Clean Technologies
      PubDate: 2022-09-02
      DOI: 10.3390/cleantechnol4030053
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 865-892: Circular Water Economy in the EU:
           Findings from Demonstrator Projects

    • Authors: Yahya Qtaishat, Jan Hofman, Kemi Adeyeye
      First page: 865
      Abstract: Circular economy (CE) for water aims to maximise value derived from water, processes, and practices. As a result, the recovery of wastewater and renewable water resources is used to offset the exploitation and impact of abstracting new water resources. New regulations such as the new circular economy action plan by the European Commission are emerging to promote circularity within the Green Deal agenda. However, there is still a need for research and practical insights into the interaction and integration of CE for water within existing policies and regulations, and its practical application specifically at the project level. This paper presents findings from demonstrator cases used to explore the opportunities and constraints in the policy, process, and procedural frameworks that govern water circularity in important sectors in Europe. Desk reviews are used to examine and compare European legislation against national and regional legislative frameworks within the different member states. Interviews and demonstrator project feedback enabled the exploration of the policy and value constraints at the project level. The findings provide unique insights into the policy and legislative enablers for and barriers to implementing CE for water in key sectors and specifically at the project level. The paper concludes with a five-point route map for new and revised policies and regulations targeting improved uptake of circular water technologies in Europe.
      Citation: Clean Technologies
      PubDate: 2022-09-07
      DOI: 10.3390/cleantechnol4030054
      Issue No: Vol. 4, No. 3 (2022)
       
  • Clean Technol., Vol. 4, Pages 234-238: Convenient Synthesis of
           Triphenylphosphine Sulfide from Sulfur and Triphenylphosphine

    • Authors: Thanh Binh Nguyen
      First page: 234
      Abstract: Elemental sulfur (S8) was found to react very rapidly (<1 min) with a stoichiometric amount of triphenylphosphine at rt in sufficient amount of solvent (0.2–0.5 mL of solvent/1 mmol of PPh3). Compared to the previously described methods, the present procedure constitute excellent access to triphenylphosphine sulfide.
      Citation: Clean Technologies
      PubDate: 2022-03-22
      DOI: 10.3390/cleantechnol4020013
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 239-257: Understanding the Anomalous
           Corrosion Behaviour of 17% Chromium Martensitic Stainless Steel in
           Laboratory CCS-Environment—A Descriptive Approach

    • Authors: Anja Pfennig, Axel Kranzmann
      First page: 239
      Abstract: To mitigate carbon dioxide emissions CO2 is compressed and sequestrated into deep geological layers (Carbon Capture and Storage CCS). The corrosion of injection pipe steels is induced when the metal is in contact with CO2 and at the same time the geological saline formation water. Stainless steels X35CrMo17 and X5CrNiCuNb16-4 with approximately 17% Cr show potential as injection pipes to engineer the Northern German Basin geological onshore CCS-site. Static laboratory experiments (T = 60 °C, p = 100 bar, 700–8000 h exposure time, aquifer water, CO2-flow rate of 9 L/h) were conducted to evaluate corrosion kinetics. The anomalous surface corrosion phenomena were found to be independent of heat treatment prior to exposure. The corrosion process is described as a function of the atmosphere and diffusion process of ionic species to explain the precipitation mechanism and better estimate the reliability of these particular steels in a downhole CCS environment.
      Citation: Clean Technologies
      PubDate: 2022-03-24
      DOI: 10.3390/cleantechnol4020014
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 258-275: Modeling of Vacuum Temperature
           Swing Adsorption for Direct Air Capture Using Aspen Adsorption

    • Authors: Thomas Deschamps, Mohamed Kanniche, Laurent Grandjean, Olivier Authier
      First page: 258
      Abstract: The paper evaluates the performance of an adsorption-based technology for CO2 capture directly from the air at the industrial scale. The approach is based on detailed mass and energy balance dynamic modeling of the vacuum temperature swing adsorption (VTSA) process in Aspen Adsorption software. The first step of the approach aims to validate the modeling thanks to published experimental data for a lab-scale bed module in terms of mass transfer and energy performance on a packed bed using amine-functionalized material. A parametric study on the main operating conditions, i.e., air velocity, air relative moisture, air temperature, and CO2 capture rate, is undertaken to assess the global performance and energy consumption. A method of up-scaling the lab-scale bed module to industrial module is exposed and mass transfer and energy performances of the industrial module are provided. The scale up from lab scale to the industrial size is conservative in terms of thermal energy consumption while the electrical consumption is very sensitive to the bed design. Further study related to the engineering solutions available to reach high global gas velocity are required. This could be offered by monolith-shape adsorbents.
      Citation: Clean Technologies
      PubDate: 2022-04-08
      DOI: 10.3390/cleantechnol4020015
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 276-295: Clean Technologies for Production
           of Valuable Fractions from Sardine Cooking Wastewaters: An Integrated
           Process of Flocculation and Reverse Osmosis

    • Authors: Maria João Pereira, Oceane Grosjean, Manuela Pintado, Carla Brazinha, João Crespo
      First page: 276
      Abstract: The increase in environmental consciousness and stricter regulations has motivated industries to seek sustainable technologies that allow valorising wastewaters, contributing to the profitability of overall processes. Canning industry effluents, namely sardine cooking wastewater, have a high organic matter load, containing proteins and lipids. Their untreated discharge has a negative environmental impact and an economic cost. This work aims to design an integrated process that creates value with the costly sardine cooking wastewater effluent. The research strategy followed evaluates coagulation/flocculation technologies as pre-treatment of the sardine cooking wastewater followed by reverse osmosis. Two different added-value products were obtained: a solid fraction rich in proteins, lipids (above 20%), and aromas that might be used for feed/pet/aquaculture applications and, from the processing of the resultant aqueous stream by reverse osmosis, a natural flavouring additive, which can be applied in food/feed. Additionally, the permeate from reverse osmosis presents a much lower organic load than the original raw material, which may be reused in the overall process (e.g., as water for washings) or discharged at a lower cost, with environmental benefits and economic savings.
      Citation: Clean Technologies
      PubDate: 2022-04-15
      DOI: 10.3390/cleantechnol4020016
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 296-308: Sorption of 71 Pharmaceuticals to
           Powder Activated Carbon for Improved Wastewater Treatment

    • Authors: Maritha Hörsing, Henrik Rasmus Andersen, Roman Grabic, Jes la Cour Jansen, Anna Ledin
      First page: 296
      Abstract: In this study, sorption distribution coefficients were determined for 71 pharmaceuticals, aiming to describe their sorption behavior to powder activated carbon (PAC). The data are expected to be applied when designing and upgrading wastewater treatment plants (WWTP) for improved removal of pharmaceuticals by applying sorption to PAC as an additional removal technique. Sorption isotherms were determined for the pharmaceuticals over a concentration interval covering a wide range from 0.08 to 10 µg/L using PAC at a concentration of 10 mg/L. The best fitted sorption isotherms were used to calculate the distribution coefficients (Kd) and these were applied to estimate that the PAC doses needed to achieve a target concentration of 10 ng/L in the effluent. A target concentration was used since neither discharge limit values nor environmental quality standards in general have been defined for these compounds. Using a %-removal approach does not guarantee achievement of concentrations low enough to protect the water ecosystems. Some of the pharmaceuticals will be reduced by the addition of small amounts of PAC. Examples are atenolol, carbamazepine, citalopram, codeine, fluoxetine and ibuprofen. For others, e.g., oxazepam, an alternative treatment has to be considered since the requested dose is too high to be realistic for a target concentration of 10 ng/L.
      Citation: Clean Technologies
      PubDate: 2022-04-25
      DOI: 10.3390/cleantechnol4020017
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 309-328: Advanced Steam Reforming of Bio-Oil
           with Carbon Capture: A Techno-Economic and CO2 Emissions Analysis

    • Authors: Jennifer Reeve, Oliver Grasham, Tariq Mahmud, Valerie Dupont
      First page: 309
      Abstract: A techno-economic analysis has been used to evaluate three processes for hydrogen production from advanced steam reforming (SR) of bio-oil, as an alternative route to hydrogen with BECCS: conventional steam reforming (C-SR), C-SR with CO2 capture (C-SR-CCS), and sorption-enhanced chemical looping (SE-CLSR). The impacts of feed molar steam to carbon ratio (S/C), temperature, pressure, the use of hydrodesulphurisation pretreatment, and plant production capacity were examined in an economic evaluation and direct CO2 emissions analysis. Bio-oil C-SR-CC or SE-CLSR may be feasible routes to hydrogen production, with potential to provide negative emissions. SE-CLSR can improve process thermal efficiency compared to C-SR-CCS. At the feed molar steam to carbon ratio (S/C) of 2, the levelised cost of hydrogen (USD 3.8 to 4.6 per kg) and cost of carbon avoided are less than those of a C-SR process with amine-based CCS. However, at higher S/C ratios, SE-CLSR does not have a strong economic advantage, and there is a need to better understand the viability of operating SE-CLSR of bio-oil at high temperatures (>850 °C) with a low S/C ratio (e.g., 2), and whether the SE-CLSR cycle can sustain low carbon deposition levels over a long operating period.
      Citation: Clean Technologies
      PubDate: 2022-04-26
      DOI: 10.3390/cleantechnol4020018
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 329-344: Thermal Investigation of a
           Turbocharger Using IR Thermography

    • Authors: Hamed Basir, Shahab Alaviyoun, Marc A. Rosen
      First page: 329
      Abstract: An experimental thermal survey of a turbocharger was performed in an engine test cell using IR thermography. The emissivity coefficients of housings were specified using a furnace and camera. It was shown that the emissivity of the turbine, compressor, and bearing housings are 0.92, 0.65, and 0.74, respectively. In addition, thermocouples were mounted on the housing to validate the temperature of the thermal camera while running in an engine test cell. To compare the data of the thermocouple with data from the thermal camera, an image was taken from the sensor’s location on the housing. The experimental results show that the temperature prediction of the thermal camera has less than 1 percent error. Steady-state tests at various working points and unsteady tests including warm-up and cool-down were performed. The measurements indicate that the turbine casing’s maximum temperature is 839 °C. Furthermore, a thermal image of the bearing housing shows that the area’s average temperature, which is close to the turbine housing, is 7 °C lower than the area close to the compressor housing. The temperature of the bearing housing near the turbine side should be higher; however, the effect of the water passing through the bearing housing decreases the temperature.
      Citation: Clean Technologies
      PubDate: 2022-04-28
      DOI: 10.3390/cleantechnol4020019
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 345-355: Green Hydrogen in the UK: Progress
           and Prospects

    • Authors: Kevin Kendall
      First page: 345
      Abstract: Green hydrogen has been known in the UK since Robert Boyle described flammable air in 1671. This paper describes how green hydrogen has become a new priority for the UK in 2021, beginning to replace fossil hydrogen production exceeding 1 Mte in 2021 when the British Government started to inject significant funding into green hydrogen sources, though much less than the USA, Germany, Japan and China. Recent progress in the UK was initiated in 2008 when the first UK green hydrogen station opened in Birmingham University, refuelling 5 hydrogen fuel cell battery electric vehicles (HFCBEVs) for the 50 PhD chemical engineering students that arrived in 2009. Only 10 kg/day were required, in contrast to the first large, green ITM power station delivering almost 600 kg/day of green hydrogen that opened in the UK, in Tyseley, in July 2021. The first question asked in this paper is: ‘What do you mean, Green'’. Then, the Clean Air Zone (CAZ) in Birmingham is described, with the key innovations defined. Progress in UK green hydrogen and fuel cell introduction is then recounted. The remarks of Elon Musk about this ‘Fool Cell; Mind bogglingly stupid’ technology are analysed to show that he is incorrect. The immediate deployment of green hydrogen stations around the UK has been planned. Another century may be needed to make green hydrogen dominant across the country, yet we will be on the correct path, once a profitable supply chain is established in 2022.
      Citation: Clean Technologies
      PubDate: 2022-04-30
      DOI: 10.3390/cleantechnol4020020
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 356-376: Examining the Development of a
           Geothermal Risk Mitigation Scheme in Greece

    • Authors: Spyridon Karytsas, Dimitrios Mendrinos, Theoni I. Oikonomou, Ioannis Choropanitis, Attila Kujbus, Constantine Karytsas
      First page: 356
      Abstract: Geothermal project development entails a number of risks, the most significant of which is the geological risk. The introduction of a risk mitigation scheme (RMS) might enable project developers to shift some of the geological risk to public or private entities. Keeping the above in mind, the objective of this study is to examine the development of an effective and financially feasible geothermal risk mitigation scheme in Greece, i.e., a country with no such scheme available. In this respect, the existing status of the geothermal sector in the country is presented, followed by an evaluation of the financial sustainability of a potential RMS, taking into account different insurance premiums, risk coverages, and project success rates. The results indicate that alternative insurance premium, risk coverage, and success rate requirements would result in different financial preconditions for the foundation either of a public or a private fund. Keeping in mind that in most examined scenarios the initial RMS capital is expended before the end of the ending of the scheme, it is suggested that such a plan can only be initiated by the public sector, which is typical of countries with little-developed geothermal markets.
      Citation: Clean Technologies
      PubDate: 2022-05-07
      DOI: 10.3390/cleantechnol4020021
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 377-379: Clean Technologies 2020 Best Paper
           Awards

    • Authors: Clean Technologies Editorial Office Clean Technologies Editorial Office
      First page: 377
      Abstract: Clean Technologies (Clean Technol.) is instituting the Best Paper Awards to recognize outstanding papers published in the journal [...]
      Citation: Clean Technologies
      PubDate: 2022-05-10
      DOI: 10.3390/cleantechnol4020022
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 380-394: Environmental Comparison of
           Different Mechanical–Biological Treatment Plants by Combining Life
           Cycle Assessment and Material Flow Analysis

    • Authors: Giovanni Gadaleta, Sabino De Gisi, Francesco Todaro, Michele Notarnicola
      First page: 380
      Abstract: The role of Mechanical–Biological Treatment (MBT) is still of the utmost importance in the management of residual Municipal Solid Waste (MSW). These plants can cover a wide range of objectives, combining several types of processes and elements. The aim of this work is to assess and compare, from an environmental point of view, the performance of seven selected MBT plants currently operating in different countries, which represent the main MBT layout and processes. For the scope, a combined Life Cycle Assessment (LCA) and Material Flow Analysis (MFA) approach has been adopted to assess plant-specific efficiencies in materials and energy recovery. Metals recovery was a common and high-efficiency practice in MBT; further recovery of other types of waste was often performed. Each assessed MBT plant achieved environmental benefits: among them, the highest environmental benefit was achieved when the highest amount of waste was recovered (not only with material recycling). Environmental results were strongly affected by the recycling processes and the energy production, with a little contribution from the energy requirement. The impacts achieved by the MBT process were, on average, 14% of the total one. The main condition for a suitable MBT process is a combination of materials recovery for the production of new raw materials, avoiding disposal in landfill, and refuse-derived fuel production for energy recovery. This work can be of help to operators and planners when they are asked to define MBT schemes.
      Citation: Clean Technologies
      PubDate: 2022-05-11
      DOI: 10.3390/cleantechnol4020023
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 395-406: An Improved Method to Estimate
           Savings from Thermal Comfort Control in Residences from Smart Wi-Fi
           Thermostat Data

    • Authors: Abdulelah D. Alhamayani, Qiancheng Sun, Kevin P. Hallinan
      First page: 395
      Abstract: The net-zero global carbon target for 2050 needs both expansion of renewable energy and substantive energy consumption reduction. Many of the solutions needed are expensive. Controlling HVAC systems in buildings based upon thermal comfort, not just temperature, uniquely offers a means for deep savings at virtually no cost. In this study, a more accurate means to quantify the savings potential in any building in which smart WiFi thermostats are present is developed. Prior research by Alhamayani et al. leveraging such data for individual residences predicted cooling energy savings in the range from 33 to 47%, but this research was based only upon a singular data-based model of indoor temperature. The present research improves upon this prior research by developing LSTM neural network models for both indoor temperature and humidity. Validation errors are reduced by nearly 22% compared to the prior work. Simulations of thermal comfort control for the residences considered yielded potential savings in the range of 29–43%, dependent upon both solar exposure and insulation characteristics of each residence. This research paves the way for smart Wi-Fi thermostat-enabled thermal comfort control in buildings of all types.
      Citation: Clean Technologies
      PubDate: 2022-05-12
      DOI: 10.3390/cleantechnol4020024
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 407-419: Enhanced Sewage Sludge Drying with
           a Modified Solar Greenhouse

    • Authors: Alice Sorrenti, Santo Fabio Corsino, Francesco Traina, Gaspare Viviani, Michele Torregrossa
      First page: 407
      Abstract: This work reports the results obtained with an innovative configuration of a closed-static solar greenhouse for sludge drying. The novelty of the solar greenhouse configuration consisted in using a forced ventilation system to provide hot air for sludge drying and the utilization of solar irradiation for energy supply. Wet sewage sludge (97% humidity) was successfully dried up to a residual humidity close to 5% after 25 days during wintertime. The increase of the airflow rate supplied under the sludge bed improved the sludge drying rate. Moreover, the fraction of volatile suspended solids decreased from 70% to 41% after 13 days, indicating that air supply promoted the simultaneous stabilization of the sludge as a side-effect to the drying process. Overall, the specific energy consumption per ton of evaporated water was estimated to approximately 450 kWh/t, resulting in about 55% of energy demand lower than a conventional thermal drying system, while using only free solar energy. The achieved high weight reduction of up to 99% implies a noticeable reduction of the excess sludge handling costs, indicating that solar greenhouse drying is a highly interesting opportunity for sludge drying in medium-small sized WWTPs.
      Citation: Clean Technologies
      PubDate: 2022-05-12
      DOI: 10.3390/cleantechnol4020025
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 420-440: Wood Biochar Enhances the
           Valorisation of the Anaerobic Digestion of Chicken Manure

    • Authors: Tien Ngo, Leadin S. Khudur, Ibrahim Gbolahan Hakeem, Kalpit Shah, Aravind Surapaneni, Andrew S. Ball
      First page: 420
      Abstract: In this study, the efficacy of biochar to mitigate ammonia stress and improve methane production is investigated. Chicken manure (CM) was subjected to high-solid mesophilic anaerobic digestion (15% total solid content) with wood biochar (BC). Wood biochar was further treated using HNO3 and NaOH to produce acid–alkali-treated wood biochar (TBC), with an improvement in its overall ammonium adsorption capacity and porosity. Three treatments were loaded in triplicate into the digesters, without biochar, with biochar and with acid–alkali-treated biochar and maintained at 37 °C for 110 days. The study found a significant improvement in CH4 formation kinetics via enhanced substrate degradation, leading to CH4 production of 74.7 mL g−1 VS and 70.1 mL g−1 VS by BC and TBC treatments, compared to 39.5 mL g−1 VS by control treatments on the 28th day, respectively. However, only the use of TBC was able to prolong methane production during the semi-inhibition phase. The use of TBC also resulted in the highest removal of total ammonia nitrogen (TAN) of 86.3%. In addition, the treatment with TBC preserved the highest microbial biomass at day 110. The presence of TBC also resulted in an increase in electrical conductivity, possibly promoting DIET-mediated methanogenesis. Overall, the acid–alkali treatment of biochar can be a novel approach to improve biochar’s existing characteristics for its utilisation as an additive in anaerobic digestion.
      Citation: Clean Technologies
      PubDate: 2022-05-13
      DOI: 10.3390/cleantechnol4020026
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 440-457: Correlations of Seismic Velocities
           and Elastic Moduli with Temperature in Superhot and Enhanced Geothermal
           Systems

    • Authors: Dimitrios Mendrinos, Constantine Karytsas, Spyridon Karytsas, Flavio Poletto, Biancamaria Farina, Erika Barison
      First page: 440
      Abstract: This paper presents correlations derived by linear regression analysis of seismic velocities VP and VS and elastic moduli EP and ES with temperature in Los Humeros superhot (SHGS) and Acoculco enhanced (EGS) geothermal systems at depths down to 3 km below the surface and temperatures up to approximately 400 °C. In Los Humeros, the seismic velocity models were derived from the inversion of legacy active seismic survey data acquired in 1998, as well as from passive seismic monitoring and ambient seismic noise interferometry carried out during 2017–2019 by the GEMex consortium. In the Acoculco EGS, ambient seismic noise data were used. Steady-state formation temperatures were re-evaluated during and after the end of the GEMex project using measurements provided as a courtesy of the Federal Electricity Commission of Mexico (CFE). The density data needed for the calculation of elastic moduli were provided by the GEMex consortium, as derived from the inversion of regional and local gravity surveys. The analysis indicated that statistically significant correlations of seismic parameters to temperature exist in the vertical direction, namely exponential in Los Humeros superhot and logarithmic in Acoculco EGS, but no correlation was evident in the horizontal direction. This result suggests an indirect relationship among the considered variables due to interdependence on other parameters, such as pressure and vapor saturation. As the analysis was performed using only data obtained from sensing-at-surface methods, without direct geophysical calibration at depth, a distributed fiber-optic seismic and temperature sensing system at both surface and downhole is proposed for active-source and passive seismic monitoring, and seismic-while-drilling by the drill-bit source is considered for reverse vertical seismic profile (RVSP) recording whenever possible for future high-temperature geothermal applications.
      Citation: Clean Technologies
      PubDate: 2022-05-16
      DOI: 10.3390/cleantechnol4020027
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 458-476: Planning a Notable CCS Pilot-Scale
           Project: A Case Study in France, Paris Basin—Ile-de-France

    • Authors: Fernanda M. L. Veloso, Isaline Gravaud, Frédéric A. Mathurin, Sabrine Ben Rhouma
      First page: 458
      Abstract: Few commercial-scale carbon capture and storage (CCS) projects are currently operating in the world, with almost all in the USA and China. Despite a high number of CCS pilot-scale projects achieved in Europe, only two commercial-scale projects are operating today. The goal of this study is to present a case study in France to select a promising location to deploy a notable CCS pilot-scale project based on a multicriteria regional-scale approach. The methodology applied in this case study describes and assesses different aspects involved in CCS technology at the regional scale, and then an evaluation of economic key performance indicators (KPI) of CCS is carried out. The assessment at the regional scale gives an overview of where CCS could be applied, when CCS could be deployed and how to launch CCS considering the needs and concerns of stakeholders in the region. Technical aspects were mapped, such as the location of irreducible CO2 sources and long-lasting emissions and the location of storage resources and existing potential transport infrastructures. We identified the waste-to-energy and chemical sectors as the main CO2 sources in the region. An economic analysis of a hypothetical scenario of CCS deployment was elaborated considering three of the higher emitters in the region. A CCS scenario in the Paris Basin region with a deployment between 2027 and 2050 indicates a low CO2 cost per ton avoided between 43 EUR/t and 70 EUR/t for a cumulated total of 25 Mt and 16 Mt, respectively, of CO2 captured and stored for 26 years, including 7.7 Mt of CO2 from biomass (potential negative emissions). Storage maturity and availability of the resource are the most uncertain parameters of the scenario, although they are the key elements to push investment in capture facilities and transport. Geological storage pilot projects are mandatory to prove storage resource and should be located in strategic locations close to potential CO2 sources in case of confirmation of proven resources. Well-perceived pilot-scale projects are the first step to start engaging in deciding and investing in commercial-scale CCS projects.
      Citation: Clean Technologies
      PubDate: 2022-05-18
      DOI: 10.3390/cleantechnol4020028
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 477-501: Review of Latest Advances and
           Prospects of Energy Storage Systems: Considering Economic, Reliability,
           Sizing, and Environmental Impacts Approach

    • Authors: Mohammadali Kiehbadroudinezhad, Adel Merabet, Homa Hosseinzadeh-Bandbafha
      First page: 477
      Abstract: Studies have shown that the role of energy storage systems in human life is increasing day by day. Therefore, this research aims to study the latest progress and technologies used to produce energy storage systems. It also discusses and compares the most recent methods used by researchers to model and optimize the size of these tools and evaluates the strengths and weaknesses of each. Investigations have shown that using energy storage systems in hybrid stand-alone power generation systems based on renewable energy increases the reliability of the power generation systems and increases their efficiency. It has also reduced the cost of transmitting the power grid to remote areas. Furthermore, this study showed that advances in energy storage technology in recent years have led to the development and promotion of clean microgrids. In addition, this review paper also addresses energy storage technology issues and proposes practical and applied solutions.
      Citation: Clean Technologies
      PubDate: 2022-06-01
      DOI: 10.3390/cleantechnol4020029
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 502-511: Genetically Engineered Organisms:
           Possibilities and Challenges of Heavy Metal Removal and Nanoparticle
           Synthesis

    • Authors: Siavash Iravani, Rajender S. Varma
      First page: 502
      Abstract: Heavy metal removal using genetically engineered organisms (GEOs) offer more cost and energy-efficient, safer, greener, and environmentally-friendly opportunities as opposed to conventional strategies requiring hazardous or toxic chemicals, complex processes, and high pressure/temperature. Additionally, GEOs exhibited superior potentials for biosynthesis of nanoparticles with significant capabilities in bioreduction of heavy metal ions that get accumulated as nanocrystals of various shapes/dimensions. In this context, GEO-aided nanoparticle assembly and the related reaction conditions should be optimized. Such strategies encompassing biosynthesized nanoparticle conforming to the green chemistry precepts help minimize the deployment of toxic precursors and capitalize on the safety and sustainability of the ensuing nanoparticle. Different GEOs with improved uptake and appropriation of heavy metal ions potentials have been examined for bioreduction and biorecovery appliances, but effective implementation to industrial-scale practices is nearly absent. In this perspective, the recent developments in heavy metal removal and nanoparticle biosynthesis using GEOs are deliberated, focusing on important challenges and future directions.
      Citation: Clean Technologies
      PubDate: 2022-06-01
      DOI: 10.3390/cleantechnol4020030
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 512-528: Effect of Ohmic Heating on the
           Extraction Yield, Polyphenol Content and Antioxidant Activity of Olive
           Mill Leaves

    • Authors: Fereshteh Safarzadeh Markhali, José A. Teixeira, Cristina M. R. Rocha
      First page: 512
      Abstract: This study examined the influence of ohmic heating (OH), compared to the conventional heating (Conven) and Control (solvent) methods, on the extraction of olive mill leaves. The main extraction parameters were: (i) solvent ratio (aqueous ethanol; 40%, 60%, and 80%, v/v), and (ii) extraction temperature; 45 °C, 55 °C, and 75 °C (for OH and Conven), and room temperature (for Control). The selected response variables were extraction yield (%), total phenolic content (TPC), and antioxidant activity (ABTS and DPPH). The ohmic system, compared to Conven and Control, exhibited the greatest effects (p < 0.001) on increasing (i) extraction yield (34.53%) at 75 °C with 80% ethanol, (ii) TPC at 55 °C (42.53, 34.35, 31.63 mg GAE/g extract, with 60%, 40%, and 80% ethanol, respectively), and (iii) antioxidant potency at 75 °C detected by DPPH and ABTS, in the range of 1.21–1.04 mM TE/g, and 0.62–0.48 mM TE/g extract, respectively. Further, there were relatively similar trends in TPC and antioxidant activity (both methods), regardless of solvent ratios, p < 0.001. These findings demonstrate the potential of ohmic heating, as a green processing tool, for efficient extraction (15 min) of olive leaves. To date, no literature has described ohmic application for olive leave extraction.
      Citation: Clean Technologies
      PubDate: 2022-06-01
      DOI: 10.3390/cleantechnol4020031
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 529-541: Assessment of Sustainable Biogas
           Production from Co-Digestion of Jatropha De-Oiled Cake and Cattle Dung
           Using Floating Drum Type Digester under Psychrophilic and Mesophilic
           Conditions

    • Authors: Amit Kumar Sharma, Pradeepta Kumar Sahoo, Mainak Mukherjee, Alok Patel
      First page: 529
      Abstract: Biodiesel is an emerging alternative fuel that is generally made from edible and non-edible oilseed crops. Jatropha curcus has a high potential for producing biodiesel, which yields 25–35% oil along with 75–65% solid byproduct, generally called a de-oiled cake. The present manuscript deals with the co-digestion of Jatropha de-oiled cake along with cattle dung (1:1 ratio) for biogas production in a floating-type biogas digester. The experimental study was carried out in a modified KVIC biogas plant of 6 cubic meter capacity for 60 days’ retention time under psychrophilic and mesophilic temperature conditions. During all the experiments, the total solid content of the slurry was maintained fixed at 10–12% by mixing 10 kg Jatropha de-oiled cake and 10 kg cattle dung with 80 kg water. The experimental results showed that the average specific biogas production of Jatropha de-oiled cake and cattle dung slurry was observed to be 0.216 m3/kg TS, 0.252 m3/kg VS and 0.287 m3/kg TS, 0.335 m3/kg VS, respectively, under the aforementioned conditions. Moreover, the biogas methane concentration was observed to be 62.33% to 69.16% under mesophilic temperature conditions compared to the psychrophilic temperature conditions, 65.21% to 69.15%, respectively. Furthermore, the average total volatile solids mass removal efficiency of feeding material in the abovementioned process was 7% higher under mesophilic temperature conditions than psychrophilic temperature conditions. Additionally, the results indicated that a total 588.8 kg of input volatile solids produced a total of 7306.56 MJ/m3 and 5177.88 MJ/m3 energy in 60 days under psychrophilic and mesophilic temperature conditions. On the basis of the results, it is concluded that Jatropha de-oiled cake may be a superior solution for improving biogas quality and composition as well as a value-added product, i.e., organic manure.
      Citation: Clean Technologies
      PubDate: 2022-06-02
      DOI: 10.3390/cleantechnol4020032
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 542-554: Seasonal Efficiency of a
           Brine-to-Water Heat Pump with Different Control Options according to
           Ecodesign Standards

    • Authors: Jaime Sieres, Ignacio Ortega, Fernando Cerdeira, Estrella Álvarez, José M. Santos
      First page: 542
      Abstract: The seasonal performance of a heat pump indicates its average performance during the heating and/or cooling season, taking into account the different energy demands and their variability over time. Several European and international regulations and policies related with energy efficiency and the reduction of the carbon footprint of energy related products are affecting the heat pump industry. Among them, the ecodesign regulations impose minimum energy efficiency values for heat pumps, efficiencies that are based on the seasonal coefficient of performance. This work is focused on a domestic brine-to-water heat pump for low-temperature applications. The methodology to determine its seasonal coefficient of performance (SCOP) according to the European standard EN 14825 is explained and evaluated based on experimental results. The impact on the SCOP of using some technology options such as fixed or variable speed compressors, and fixed or variable outlet temperature operation is evaluated. Results show that between the lowest and highest efficient option, the SCOP can be improved by 26%.
      Citation: Clean Technologies
      PubDate: 2022-06-16
      DOI: 10.3390/cleantechnol4020033
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 555-569: Performance Evaluation of Roughened
           Solar Air Heaters for Stretched Parameters

    • Authors: Mustafa Alaskari, Arwa M. Kadhim, Ammar A. Farhan, Moustafa Al-Damook, Mansour Al Qubeissi
      First page: 555
      Abstract: Artificial roughness applied to a Solar Air Heater (SAH) absorber plate is a popular technique for increasing its total thermal efficiency (ηt−th). In this paper, the influence of geometrical parameters of V-down ribs attached below the corrugated absorbing plate of a SAH on the ηt−th was examined. The impacts of key roughness parameters, including relative pitch p/e (6–12), relative height e/D (0.019–0.043), angles of attack α (30–75°), and Re (1000–20,000), were examined under real weather conditions. The SAH ηt−th roughened by V-down ribs was predicted using an in-house developed conjugate heat-transfer numerical model. The maximum SAH ηt−th was shown to be 78.8% as predicted under the steady-state conditions of Re = 20,000, solar irradiance G = 1000 W/m2, p/e = 8, e/D = 0.043, and α = 60. The result was 15.7% greater efficiency compared to the default smooth surface. Under real weather conditions, the ηt−th of the roughened SAH with single- and double-glass covers were 17.7 and 20.1%, respectively, which were higher than those of the smooth SAH.
      Citation: Clean Technologies
      PubDate: 2022-06-16
      DOI: 10.3390/cleantechnol4020034
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 570-583: Carbon Footprint and Total Cost
           Evaluation of Different Bio-Plastics Waste Treatment Strategies

    • Authors: Giovanni Gadaleta, Sabino De Gisi, Francesco Todaro, Michele Notarnicola
      First page: 570
      Abstract: To address the problem of fossil-based pollution, bio-plastics have risen in use in a wide range of applications. The current waste management system still has some weakness for bio-plastics waste (BPW) treatment, and quantitative data is lacking. This study combines environmental and economic assessments in order to indicate the most sustainable and suitable BPW management treatment between organic, plastic and mixed wastes. For the scope, the carbon footprint of each scenario was calculated by life cycle assessment (LCA), while the total cost of the waste management system was used as an economic parameter. The economic evaluation revealed that the organic, plastic and mixed waste treatment routes reached a total cost of 120.35, 112.21 and 109.43 EUR, respectively. The LCA results showed that the incomplete degradation of BPW during anaerobic digestion and composting led to the disposal of the compost produced, creating an environmental burden of 324.64 kgCO2-Eq. for the organic waste treatment route, while the mixed and plastic treatment routes obtained a benefit of −87.16 and −89.17 kgCO2-Eq. respectively. This study showed that, although the current amount of BPW does not affect the treatment process of organic, plastic and mixed wastes, it can strongly affect the quality of the output, compromising its further reuse. Therefore, specific improvement of waste treatment should be pursued, particularly with regard to the anaerobic digestion of organic waste, which remains a promising technology for BPW treatment.
      Citation: Clean Technologies
      PubDate: 2022-06-16
      DOI: 10.3390/cleantechnol4020035
      Issue No: Vol. 4, No. 2 (2022)
       
  • Clean Technol., Vol. 4, Pages 1-13: Solar Photovoltaic System-Based
           Reduced Switch Multilevel Inverter for Improved Power Quality

    • Authors: Madhu Andela, Ahmmadhussain Shaik, Saicharan Beemagoni, Vishal Kurimilla, Rajagopal Veramalla, Amritha Kodakkal, Surender Reddy Salkuti
      First page: 1
      Abstract: This paper deals with a reduced switch multi-level inverter for the solar photovoltaic system-based 127-level multi-level inverter. The proposed technique uses the minimum number of switches to achieve the maximum steps in staircase AC output voltage when compared to the flying capacitor multi-level inverter, cascaded type multilevel inverter and diode clamped multi-level inverter. The use of a minimum number of switches decreases the cost of the system. To eliminate the switching losses, in this topology a square wave switch is used instead of pulse width modulation. Thereby the total harmonic distortion (THD) and harmonics have been reduced in the pulsating AC output voltage waveform. The performance of 127-level MLI is compared with 15 level, 31-level and 63-level multilevel inverters. The outcomes of the solar photovoltaic system-based 127-level multi-level inverter have been simulated in a MATLAB R2009b environment.
      Citation: Clean Technologies
      PubDate: 2022-01-02
      DOI: 10.3390/cleantechnol4010001
      Issue No: Vol. 4, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 14-34: Techno-Economic Analysis and
           Modelling of the Feasibility of Wind Energy in Kuwait

    • Authors: Ali M. H. A. Khajah, Simon P. Philbin
      First page: 14
      Abstract: There continues to be significant attention and investment in wind power generation, which can supply a high percentage of the global demand for renewable energy if harvested efficiently. The research study is based on a techno-economic analysis of the feasibility of implementing wind power generation in Kuwait for 105 MW of electricity generation based on 50 wind turbines, which is a major requirement for clean energy. The study focused on three main areas of analysis and numerical modelling using the RETScreen software tool. The first area involved evaluating the performance and efficacy of generating wind power by collecting, analysing, and modelling data on observed wind levels, wind turbine operation, and wind power generation. The second area comprised an environmental impact report to assess the environmental benefits of implementing wind power. The third area involved economic analysis of installing wind power in Kuwait. The analysis was undertaken to determine the energy recovery time for wind energy and determine the mitigation of global warming and pollution levels, the decrease of toxic emissions, and any cost savings from implementing clean energy systems in Kuwait. Additionally, sensitivity analysis was undertaken to determine the impact of certain variables in the modelling process. The results were used to estimate that the energy price would be $0.053 per kWh for a power generation capacity of 105 MWh based on an initial cost of US $168 million and O&M of $5 million for 214,000 MWh of electricity exported to the grid. Moreover, the wind turbine farm will potentially avoid the emission of approximately 1.8 million t of carbon dioxide per year, thereby saving about $9 million over 20 years spent through installing carbon capture systems for conventional power plants. The wind farm is estimated to have a payback time of 9.1 years.
      Citation: Clean Technologies
      PubDate: 2022-01-10
      DOI: 10.3390/cleantechnol4010002
      Issue No: Vol. 4, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 35-50: Biogas, Biomethane and Digestate
           Potential of By-Products from Green Biorefinery Systems

    • Authors: Rajeev Ravindran, Kwame Donkor, Lalitha Gottumukkala, Abhay Menon, Amita Jacob Guneratnam, Helena McMahon, Sybrandus Koopmans, Johan P. M. Sanders, James Gaffey
      First page: 35
      Abstract: Global warming and climate change are imminent threats to the future of humankind. A shift from the current reliance on fossil fuels to renewable energy is key to mitigating the impacts of climate change. Biological raw materials and residues can play a key role in this transition through technologies such as anaerobic digestion. However, biological raw materials must also meet other existing food, feed and material needs. Green biorefinery is an innovative concept in which green biomass, such as grass, is processed to obtain a variety of protein products, value-added co-products and renewable energy, helping to meet many needs from a single source. In this study, an analysis has been conducted to understand the renewable energy potential of green biorefinery by-products and residues, including grass whey, de-FOS whey and press cake. Using anaerobic digestion, the biogas and biomethane potential of these samples have been analyzed. An analysis of the fertiliser potential of the resulting digestate by-products has also been undertaken. All the feedstocks tested were found to be suitable for biogas production with grass whey, the most suitable candidate with a biogas and biomethane production yield of 895.8 and 544.6 L/kg VS, respectively, followed by de-FOS whey and press cake (597.4/520.3 L/kg VS and 510.7/300.3 L/kg VS, respectively). The results show considerable potential for utilizing biorefinery by-products as a source for renewable energy production, even after several value-added products have been co-produced.
      Citation: Clean Technologies
      PubDate: 2022-01-17
      DOI: 10.3390/cleantechnol4010003
      Issue No: Vol. 4, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 51-52: Acknowledgment to Reviewers of Clean
           Technologies in 2021

    • Authors: Clean Technologies Editorial Office Clean Technologies Editorial Office
      First page: 51
      Abstract: Rigorous peer-reviews are the basis of high-quality academic publishing [...]
      Citation: Clean Technologies
      PubDate: 2022-01-26
      DOI: 10.3390/cleantechnol4010004
      Issue No: Vol. 4, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 53-66: Encapsulated EVOO Improves Food
           Safety and Shelf Life of Refrigerated Pre-Cooked Chicken Nuggets

    • Authors: Marta Barón-Yusty, Ginés Benito Martínez-Hernández, María Ros-Chumillas, Laura Navarro-Segura, Antonio López-Gómez
      First page: 53
      Abstract: (1) Background: New clean technologies are needed to reduce the high frying oil waste in the food industry of fried breaded products, together with the obtention of healthier (less fat content) and safer (less microbial growth and acrylamide formation) breaded products; (2) Methods: This study proposes the new technology consisting of incorporation of encapsulated extra virgin olive oil (EVOO) (α-cyclodextrin: EVOO ratio, 1:2.6) in the breadcrumbs (corn breadcrumbs:encapsulated oil ratio, 2:1) for breading chicken nuggets combined with oil-free pre-cooking (baking 150 °C/5 min) and cooking (baking 180 °C/13 min). As controls, a conventional deep-fat frying (180 °C/30 s) and new technology but without encapsulated EVOO were used; (3) Results: Fat content of baked chicken nuggets with the new technology was reduced by 88%, while no sensory differences were scored compared with conventional deep-fat frying. Furthermore, acrylamide formation was reduced by >55% with the new technology. During storage (4 °C) of pre-cooked chicken nuggets of new technology, microbial growth was reduced by 1.4 log units lower compared with deep-fat frying method; (4) Conclusions: the proposed new technology, based on encapsulated EVOO+oil-free pre-cooking/cooking, allows to obtain chicken nuggets that are healthier, safer, and have a longer shelf-life, while frying oil waste is avoided.
      Citation: Clean Technologies
      PubDate: 2022-02-02
      DOI: 10.3390/cleantechnol4010005
      Issue No: Vol. 4, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 67-90: A Social Exploration of the West
           Australian Gorgon Gas, Carbon Capture and Storage Project

    • Authors: Jonathan Paul Marshall
      First page: 67
      Abstract: Carbon capture and storage (CCS) appears to be essential for lowering emissions during the necessary energy transition. However, in Australia, it has not delivered this result, at any useful scale, and this needs explanation. To investigate the reasons for this failure, the paper undertakes a historical and social case study of the Gorgon gas project in Western Australia, which is often declared to be one of the biggest CCS projects in the world. The Gorgon project could be expected to succeed, as it has the backing of government, a practical and economic reason for removing CO2, a history of previous exploration, nearby storage sites, experienced operators and managers, and long-term taxpayer liability for problems. However, it has run late, failed to meet its targets, and not lowered net emissions. The paper explores the social factors which seem to be disrupting the process. These factors include the commercial imperatives of the operation, the lack of incentives, the complexity of the process, the presence of ignored routine problems, geological issues (even in a well-explored area), technical failures, regulatory threats even if minor, tax issues, and the project increasing emissions and consuming carbon budgets despite claims otherwise. The results of this case study suggest that CCS may work in theory, but not well enough under some contemporary forms of social organisation, and the possibilities of CCS cannot be separated from its social background. Social dynamics should be included in CCS projections to enhance the accuracy of expectations.
      Citation: Clean Technologies
      PubDate: 2022-02-09
      DOI: 10.3390/cleantechnol4010006
      Issue No: Vol. 4, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 91-96: Water and Wastewater Treatment:
           Selected Topics

    • Authors: Krzysztof Barbusiński, Krzysztof Filipek
      First page: 91
      Abstract: Currently, there is a real need for rapid progress and development in almost all industries and areas of human activity [...]
      Citation: Clean Technologies
      PubDate: 2022-02-14
      DOI: 10.3390/cleantechnol4010007
      Issue No: Vol. 4, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 97-131: Integration of Solar Process Heat in
           Industries: A Review

    • Authors: Nahin Tasmin, Shahjadi Hisan Farjana, Md Rashed Hossain, Santu Golder, M. A. Parvez Mahmud
      First page: 97
      Abstract: Industrial manufacturing approaches are associated with processing materials that consume a significant amount of thermal energy, termed as industrial process heat. Industrial sectors consume a substantial amount of energy for process heating over a wide range of temperatures (up to 400 °C) from agriculture, HVAC to power plants. However, the intensive industrial application of fossil fuels causes unfavorable environmental effects that cannot be ignored. To address this issue, green energy sources have manifested their potential as economical and pollution-free energy sources. Nevertheless, the adoption of solar industrial process heating systems is still limited due to a lack of knowledge in the design/installation aspects, reluctance to experience the technical/infrastructural changes, low price of fossil fuels, and lack of relative incentives. For successful solar process heat integration in industries, a proper understanding of the associated design factors is essential. This paper comprehensively reviews the integration strategies of solar industrial process heating systems, appraisal of the integration points, different aspects of solar collectors, installed thermal power, and thermal storage volume covering case studies, reports and reviews. The integration aspects of solar process heat, findings, and obstacles of several projects from the literature are also highlighted. Finally, the integration locations of SHIP systems are compared for different industrial sectors to find out the most used integration point for a certain sector and operation. It was found that for the food, beverage, and agriculture sector, 51% of solar process heat integration occurs at the supply level and 27.3% at the process-level.
      Citation: Clean Technologies
      PubDate: 2022-02-17
      DOI: 10.3390/cleantechnol4010008
      Issue No: Vol. 4, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 132-148: Greenhouse Gas Implications of
           Extending the Service Life of PEM Fuel Cells for Automotive Applications:
           A Life Cycle Assessment

    • Authors: Alessandro Arrigoni, Valeria Arosio, Andrea Basso Peressut, Saverio Latorrata, Giovanni Dotelli
      First page: 132
      Abstract: A larger adoption of hydrogen fuel-cell electric vehicles (FCEVs) is typically included in the strategies to decarbonize the transportation sector. This inclusion is supported by life-cycle assessments (LCAs), which show the potential greenhouse gas (GHG) emission benefit of replacing internal combustion engine vehicles with their fuel cell counterpart. However, the literature review performed in this study shows that the effects of durability and performance losses of fuel cells on the life-cycle environmental impact of the vehicle have rarely been assessed. Most of the LCAs assume a constant fuel consumption (ranging from 0.58 to 1.15 kgH2/100 km) for the vehicles throughout their service life, which ranges in the assessments from 120,000 to 225,000 km. In this study, the effect of performance losses on the life-cycle GHG emissions of the vehicles was assessed based on laboratory experiments. Losses have the effect of increasing the life-cycle GHG emissions of the vehicle up to 13%. Moreover, this study attempted for the first time to investigate via laboratory analyses the GHG implications of replacing the hydrophobic polymer for the gas diffusion medium (GDM) of fuel cells to increase their durability. LCA showed that when the service life of the vehicle was fixed at 150,000 km, the GHG emission savings of using an FC with lower performance losses (i.e., FC coated with fluorinated ethylene propylene (FEP) instead of polytetrafluoroethylene (PTFE)) are negligible compared to the overall life-cycle impact of the vehicle. Both the GDM coating and the amount of hydrogen saved account for less than 2% of the GHG emissions arising during vehicle operation. On the other hand, when the service life of the vehicle depends on the operability of the fuel cell, the global warming potential per driven km of the FEP-based FCEV reduces by 7 to 32%. The range of results depends on several variables, such as the GHG emissions from hydrogen production and the initial fuel consumption of the vehicle. Higher GHG savings are expected from an FC vehicle with high consumption of hydrogen produced with fossil fuels. Based on the results, we recommend the inclusion of fuel-cell durability in future LCAs of FCEVs. We also advocate for more research on the real-life performance of fuel cells employing alternative materials.
      Citation: Clean Technologies
      PubDate: 2022-02-23
      DOI: 10.3390/cleantechnol4010009
      Issue No: Vol. 4, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 149-152: Integration and Control of
           Distributed Renewable Energy Resources

    • Authors: Hamidreza Nazaripouya
      First page: 149
      Abstract: The increase in the population growth rate and the motivation to overcome issues such as environmental concerns and air pollution have made distributed renewable energy resources (DRER) the most popular option for providing the required energy [...]
      Citation: Clean Technologies
      PubDate: 2022-03-01
      DOI: 10.3390/cleantechnol4010010
      Issue No: Vol. 4, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 153-173: Application of Machine Learning to
           Accelerate Gas Condensate Reservoir Simulation

    • Authors: Anna Samnioti, Vassiliki Anastasiadou, Vassilis Gaganis
      First page: 153
      Abstract: According to the roadmap toward clean energy, natural gas has been pronounced as the perfect transition fuel. Unlike usual dry gas reservoirs, gas condensates yield liquid which remains trapped in reservoir pores due to high capillarity, leading to the loss of an economically valuable product. To compensate, the gas produced on the surface is stripped from its heavy components and reinjected back to the reservoir as dry gas thus causing revaporization of the trapped condensate. To optimize this gas recycling process compositional reservoir simulation is utilized, which, however, takes very long to complete due to the complexity of the governing differential equations implicated. The calculations determining the prevailing k-values at every grid block and at each time step account for a great part of total CPU time. In this work machine learning (ML) is employed to accelerate thermodynamic calculations by providing the prevailing k-values in a tiny fraction of the time required by conventional methods. Regression tools such as artificial neural networks (ANNs) are trained against k-values that have been obtained beforehand by running sample simulations on small domains. Subsequently, the trained regression tools are embedded in the simulators acting thus as proxy models. The prediction error achieved is shown to be negligible for the needs of a real-world gas condensate reservoir simulation. The CPU time gain is at least one order of magnitude, thus rendering the proposed approach as yet another successful step toward the implementation of ML in the clean energy field.
      Citation: Clean Technologies
      PubDate: 2022-03-01
      DOI: 10.3390/cleantechnol4010011
      Issue No: Vol. 4, No. 1 (2022)
       
  • Clean Technol., Vol. 4, Pages 174-233: The Energy Efficiency Post-COVID-19
           in China’s Office Buildings

    • Authors: Carlos C. Duarte, Nuno D. Cortiços
      First page: 174
      Abstract: China promptly took the leading step to mitigate the spread of COVID-19, producing the first scientific guidelines assuming health above energy consumption and significantly changing HVAC/AHU operation. The research intended to fulfill the gap by measuring the impact of the guidelines on energy use intensity, CO2 emissions, and energy operation costs related to workplaces. The guidelines are long-term sector and industry trends following occupants’ health and safety concerns, and today they are applied to nursing homes. The research extended the study to post-COVID-19 scenarios by crossing those settings with published reports on telework predictions. The methodology resorts to Building Energy Simulation software to assess the Chinese standard large office building on 8 climate zones and 17 subzones between pre- and post-COVID-19 scenarios under those guidelines. The outcomes suggest an upward trend in energy use intensity (11.70–12.46%), CO2 emissions (11.13–11.76%), and costs (9.37–9.89%) for buildings located in “warm/mixed” to “subarctic” climates, especially in colder regions with high heating demands. On the other hand, the figures for “very hot” to “hot/warm” climates lower the energy use intensity (14.76–15.47%), CO2 emissions (9%), and costs (9.64–9.77%).
      Citation: Clean Technologies
      PubDate: 2022-03-02
      DOI: 10.3390/cleantechnol4010012
      Issue No: Vol. 4, No. 1 (2022)
       
 
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