Subjects -> ENERGY (Total: 414 journals)
    - ELECTRICAL ENERGY (12 journals)
    - ENERGY (252 journals)
    - ENERGY: GENERAL (7 journals)
    - NUCLEAR ENERGY (40 journals)
    - PETROLEUM AND GAS (58 journals)
    - RENEWABLE ENERGY (45 journals)

ENERGY (252 journals)                  1 2 | Last

Showing 1 - 200 of 406 Journals sorted by number of followers
Energy Policy     Partially Free   (Followers: 77)
IET Power Electronics     Open Access   (Followers: 69)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 55)
IEEE Transactions on Power Systems     Hybrid Journal   (Followers: 48)
Energy     Partially Free   (Followers: 41)
Journal of Physical Chemistry C     Hybrid Journal   (Followers: 37)
Nature Energy     Hybrid Journal   (Followers: 37)
IEEE Power and Energy     Full-text available via subscription   (Followers: 34)
International Journal of Hydrogen Energy     Partially Free   (Followers: 34)
Applied Energy     Partially Free   (Followers: 32)
Energy & Fuels     Hybrid Journal   (Followers: 29)
Solar Energy Materials and Solar Cells     Hybrid Journal   (Followers: 29)
Advances in High Energy Physics     Open Access   (Followers: 26)
Advances in Natural Sciences : Nanoscience and Nanotechnology     Open Access   (Followers: 26)
Energy & Environment     Hybrid Journal   (Followers: 25)
Energy and Power Engineering     Open Access   (Followers: 23)
Applied Solar Energy     Hybrid Journal   (Followers: 21)
International Journal of Alternative Propulsion     Hybrid Journal   (Followers: 21)
International Journal of Turbomachinery, Propulsion and Power     Open Access   (Followers: 21)
Solar Energy     Hybrid Journal   (Followers: 20)
Energy Materials : Materials Science and Engineering for Energy Systems     Hybrid Journal   (Followers: 19)
Journal of Solar Energy Engineering     Full-text available via subscription   (Followers: 19)
Water International     Hybrid Journal   (Followers: 19)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 18)
Energy and Power     Open Access   (Followers: 18)
IEEE Transactions on Energy Conversion     Hybrid Journal   (Followers: 16)
Nuclear Engineering and Design     Hybrid Journal   (Followers: 16)
Energy, Sustainability and Society     Open Access   (Followers: 16)
Economics and Policy of Energy and the Environment     Full-text available via subscription   (Followers: 16)
Energy Conversion and Management     Hybrid Journal   (Followers: 15)
Progress in Energy and Combustion Science     Hybrid Journal   (Followers: 14)
Waste Management     Hybrid Journal   (Followers: 14)
Energy and Environment Research     Open Access   (Followers: 14)
Journal of Power Electronics & Power Systems     Full-text available via subscription   (Followers: 14)
Advances in Energy and Power     Open Access   (Followers: 14)
Surface Science Reports     Full-text available via subscription   (Followers: 13)
Annual Review of Resource Economics     Full-text available via subscription   (Followers: 13)
Energy Journal The     Hybrid Journal   (Followers: 13)
Energy Research & Social Science     Full-text available via subscription   (Followers: 13)
Energy and Buildings     Hybrid Journal   (Followers: 12)
International Journal of Sustainable Energy     Hybrid Journal   (Followers: 12)
Oil and Gas Journal     Full-text available via subscription   (Followers: 12)
Biofuels     Hybrid Journal   (Followers: 12)
Journal of Solar Energy     Open Access   (Followers: 12)
Journal of Renewable Energy     Open Access   (Followers: 12)
Advances in Building Energy Research     Hybrid Journal   (Followers: 11)
Energy Systems     Hybrid Journal   (Followers: 11)
International Journal of Thermodynamics     Open Access   (Followers: 11)
Joule     Hybrid Journal   (Followers: 11)
IEEE Transactions on Nuclear Science     Hybrid Journal   (Followers: 10)
Innovations : Technology, Governance, Globalization     Hybrid Journal   (Followers: 10)
International Journal of Energy Research     Hybrid Journal   (Followers: 10)
Energy Efficiency     Hybrid Journal   (Followers: 10)
Journal of Ocean and Climate     Open Access   (Followers: 10)
Energy Science and Technology     Open Access   (Followers: 10)
Energy Strategy Reviews     Open Access   (Followers: 10)
Biomass Conversion and Biorefinery     Partially Free   (Followers: 10)
Batteries     Open Access   (Followers: 10)
ACS Energy Letters     Hybrid Journal   (Followers: 10)
Archives of Thermodynamics     Open Access   (Followers: 9)
Journal of Modern Power Systems and Clean Energy     Open Access   (Followers: 9)
International Journal of Global Energy Issues     Hybrid Journal   (Followers: 8)
International Journal of Green Energy     Hybrid Journal   (Followers: 8)
Smart Grid and Renewable Energy     Open Access   (Followers: 8)
Wiley Interdisciplinary Reviews : Energy and Environment     Hybrid Journal   (Followers: 8)
International Journal of Energy and Power     Open Access   (Followers: 8)
American Journal of Energy Research     Open Access   (Followers: 8)
CERN courier. International journal of high energy physics     Free   (Followers: 8)
Energy and Environment Focus     Free   (Followers: 8)
Annals of Nuclear Energy     Hybrid Journal   (Followers: 7)
Fuel and Energy Abstracts     Full-text available via subscription   (Followers: 7)
International Journal of Electric and Hybrid Vehicles     Hybrid Journal   (Followers: 7)
Applied Nanoscience     Open Access   (Followers: 7)
Environmental Progress & Sustainable Energy     Hybrid Journal   (Followers: 7)
Energy Storage Materials     Full-text available via subscription   (Followers: 7)
ACS Applied Energy Materials     Hybrid Journal   (Followers: 7)
Structural Control and Health Monitoring     Hybrid Journal   (Followers: 6)
Energy Prices and Taxes     Full-text available via subscription   (Followers: 6)
Journal of Building Performance Simulation     Hybrid Journal   (Followers: 6)
Materials for Renewable and Sustainable Energy     Open Access   (Followers: 6)
Energy Science & Engineering     Open Access   (Followers: 6)
American Journal of Energy and Environment     Open Access   (Followers: 6)
Atomic Energy     Hybrid Journal   (Followers: 5)
Carbon Management     Open Access   (Followers: 5)
Journal of Energy Technologies and Policy     Open Access   (Followers: 5)
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 5)
Energy Studies Review     Open Access   (Followers: 5)
Energy Technology     Partially Free   (Followers: 5)
Geothermal Energy     Open Access   (Followers: 5)
Frontiers in Energy Research     Open Access   (Followers: 5)
Journal of Energy, Environment & Carbon Credits     Full-text available via subscription   (Followers: 5)
International Journal of Sustainable Energy Planning and Management     Open Access   (Followers: 5)
Energy and Environmental Engineering     Open Access   (Followers: 5)
Energy Reports     Open Access   (Followers: 5)
Journal of Energy & Natural Resources Law     Hybrid Journal   (Followers: 5)
Annual Reports on NMR Spectroscopy     Full-text available via subscription   (Followers: 4)
Frontiers in Energy     Hybrid Journal   (Followers: 4)
International Journal of Nuclear Energy Science and Technology     Hybrid Journal   (Followers: 4)
Journal of Photochemistry and Photobiology B: Biology     Hybrid Journal   (Followers: 4)
Wind Energy     Hybrid Journal   (Followers: 4)
Strategic Planning for Energy and the Environment     Hybrid Journal   (Followers: 4)
International Journal of Sustainable Engineering     Hybrid Journal   (Followers: 4)
Dams and Reservoirs     Hybrid Journal   (Followers: 4)
Journal of Nano Energy and Power Research     Full-text available via subscription   (Followers: 4)
International Journal of Energy and Environmental Engineering     Open Access   (Followers: 4)
Science and Technology for Energy Transition     Open Access   (Followers: 4)
International Journal of Applied Power Engineering     Open Access   (Followers: 4)
Development of Energy Science     Open Access   (Followers: 4)
Journal of International Energy Policy     Open Access   (Followers: 4)
Foundations and Trends® in Renewable Energy     Full-text available via subscription   (Followers: 4)
International Journal of Energy and Statistics     Hybrid Journal   (Followers: 4)
Sustainable Energy, Grids and Networks     Hybrid Journal   (Followers: 4)
Journal of Energy Chemistry     Full-text available via subscription   (Followers: 4)
Journal of Energy Storage     Full-text available via subscription   (Followers: 4)
Journal of Energy, Mechanical, Material and Manufacturing Engineering     Open Access   (Followers: 4)
Journal of Fusion Energy     Hybrid Journal   (Followers: 3)
Journal of Photochemistry and Photobiology A: Chemistry     Hybrid Journal   (Followers: 3)
Journal of Photochemistry and Photobiology C: Photochemistry Reviews     Full-text available via subscription   (Followers: 3)
Global Energy Law and Sustainability     Hybrid Journal   (Followers: 3)
Science and Technology of Nuclear Installations     Open Access   (Followers: 3)
Power Technology and Engineering     Hybrid Journal   (Followers: 3)
Functional Materials Letters     Hybrid Journal   (Followers: 3)
Distributed Generation & Alternative Energy Journal     Hybrid Journal   (Followers: 3)
Sustainable Energy     Open Access   (Followers: 3)
Journal of Technology Innovations in Renewable Energy     Hybrid Journal   (Followers: 3)
Journal of Ocean Engineering and Marine Energy     Hybrid Journal   (Followers: 3)
International Journal of Coal Science & Technology     Open Access   (Followers: 3)
Energy and Emission Control Technologies     Open Access   (Followers: 3)
Asian Bulletin of Energy Economics and Technology     Open Access   (Followers: 3)
Protection and Control of Modern Power Systems     Open Access   (Followers: 3)
Sustainable Energy & Fuels     Hybrid Journal   (Followers: 3)
International Journal of Nuclear Knowledge Management     Hybrid Journal   (Followers: 2)
Progress in Nuclear Energy     Hybrid Journal   (Followers: 2)
Electricity Journal     Hybrid Journal   (Followers: 2)
Proceedings of the Institution of Civil Engineers - Energy     Hybrid Journal   (Followers: 2)
Gcb Bioenergy     Open Access   (Followers: 2)
Journal of Semiconductors     Full-text available via subscription   (Followers: 2)
EPJ Photovoltaics     Open Access   (Followers: 2)
International Journal of Clean Coal and Energy     Open Access   (Followers: 2)
Washington and Lee Journal of Energy, Climate, and the Environment     Open Access   (Followers: 2)
Journal of Energy in Southern Africa     Open Access   (Followers: 2)
Journal of Alternate Energy Sources & Technologies     Full-text available via subscription   (Followers: 2)
Journal of Nuclear Energy Science & Power Generation Technology     Hybrid Journal   (Followers: 2)
Nigerian Journal of Technological Research     Full-text available via subscription   (Followers: 2)
Journal of Energy     Open Access   (Followers: 2)
Energy Technology & Policy     Open Access   (Followers: 2)
Biofuel Research Journal     Open Access   (Followers: 2)
Green Energy & Environment     Open Access   (Followers: 2)
Materials Today Energy     Hybrid Journal   (Followers: 2)
Journal of Power and Energy Engineering     Open Access   (Followers: 2)
Clean Energy     Open Access   (Followers: 2)
Global Challenges     Open Access   (Followers: 2)
Carbon Resources Conversion     Open Access   (Followers: 2)
IET Smart Grid     Open Access   (Followers: 2)
IET Energy Systems Integration     Open Access   (Followers: 2)
International Journal of Nuclear Desalination     Hybrid Journal   (Followers: 1)
International Journal of Nuclear Hydrogen Production and Applications     Hybrid Journal   (Followers: 1)
Radioprotection     Hybrid Journal   (Followers: 1)
Nuclear Law Bulletin     Full-text available via subscription   (Followers: 1)
International Journal of Power and Energy Conversion     Hybrid Journal   (Followers: 1)
Clefs CEA     Full-text available via subscription   (Followers: 1)
Journal of Computational Multiphase Flows     Open Access   (Followers: 1)
Natural Resources     Open Access   (Followers: 1)
Journal of Sustainable Bioenergy Systems     Full-text available via subscription   (Followers: 1)
Open Journal of Energy Efficiency     Open Access   (Followers: 1)
Michigan Journal of Sustainability     Open Access   (Followers: 1)
Technology Audit and Production Reserves     Open Access   (Followers: 1)
Sustainable Energy Technologies and Assessments     Full-text available via subscription   (Followers: 1)
International Journal of Smart Grid and Green Communications     Hybrid Journal   (Followers: 1)
Clean Technologies     Open Access   (Followers: 1)
Energy Conversion and Management : X     Open Access   (Followers: 1)
Technology and Economics of Smart Grids and Sustainable Energy     Hybrid Journal   (Followers: 1)
Energy, Ecology and Environment     Hybrid Journal   (Followers: 1)
International Journal of Energy and Water Resources     Hybrid Journal  
BioPhysical Economics and Resource Quality     Hybrid Journal  
Geomechanics and Geophysics for Geo-Energy and Geo-Resources     Hybrid Journal  
BMC Energy     Open Access  
Journal of Energy and Environment Technology of Graduate School Siam Technology College     Open Access  
Global Energy Interconnection     Open Access  
Journal of Energy Systems     Open Access  
International Journal of Energy & Engineering Sciences     Open Access  
International Journal of Energy and Smart Grid     Open Access  
Turkish Journal of Energy Policy     Open Access  
Energy Informatics     Open Access  
High Voltage     Open Access  
Geomechanics for Energy and the Environment     Full-text available via subscription  
ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations     Open Access  
Journal of China Coal Society     Open Access  
Facta Universitatis, Series : Electronics and Energetics     Open Access  
Universal Journal of Applied Science     Open Access  
Ingeniería Energética     Open Access  
E3S Web of Conferences     Open Access  
International Journal of Ambient Energy     Hybrid Journal  
CT&F - Ciencia, Tecnología y Futuro     Open Access  
Multequina     Open Access  
South Pacific Journal of Natural and Applied Sciences     Hybrid Journal  
Chain Reaction     Full-text available via subscription  
Wind Engineering     Hybrid Journal  
Nuclear Data Sheets     Full-text available via subscription  
International Journal of Nuclear Governance, Economy and Ecology     Hybrid Journal  

        1 2 | Last

Similar Journals
Journal Cover
Clean Technologies
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2571-8797
Published by MDPI Homepage  [258 journals]
  • Clean Technol., Vol. 5, Pages 1159-1185: Heat Recovery Potential in a
           Semi-Closed Greenhouse for Tomato Cultivation

    • Authors: Abdelouhab Labihi, Paul Byrne, Amina Meslem, Florence Collet, Sylvie Prétot
      First page: 1159
      Abstract: This study first presents the development and the experimental validation of a numerical model of a semi-closed greenhouse using a dynamic thermal simulation. The second objective was to identify the influential parameters on the indoor climate and to calculate the heating demand of the greenhouse. The model reproduced the behavior of a full-scale experimental greenhouse in Carquefou (France). The comparison with experimental measurements recorded over an entire season of tomato cultivation validated the numerical model. The result of the simulated energy consumption was 310 kWh/m2/year with a relative error of 3.5%. The parametric study identified that the evapotranspiration power and ventilation rate were the most influential input variables, accounting for 50% and 32%, respectively, of the heating demand. The most sensitive output variable was indoor humidity. The presence of a thermal buffer zone all around the greenhouse reduced the energy consumption by 48%, and thermal/shading screens reduced it by 30%. The final objective was to assess the amount of heat recovery potential over the year and each week, depending on the energy storage strategy. Around 43 kWh/m2/year can be recovered over the year, leading to a potential energy savings of 24%.
      Citation: Clean Technologies
      PubDate: 2023-09-22
      DOI: 10.3390/cleantechnol5040058
      Issue No: Vol. 5, No. 4 (2023)
  • Clean Technol., Vol. 5, Pages 1186-1202: Quantitating Wastewater
           Characteristic Parameters Using Neural Network Regression Modeling on
           Spectral Reflectance

    • Authors: Dhan Lord B. Fortela, Armani Travis, Ashley P. Mikolajczyk, Wayne Sharp, Emmanuel Revellame, William Holmes, Rafael Hernandez, Mark E. Zappi
      First page: 1186
      Abstract: Wastewater (WW) analysis is a critical step in various operations, such as the control of a WW treatment facility, and speeding up the analysis of WW quality can significantly improve such operations. This work demonstrates the capability of neural network (NN) regression models to estimate WW characteristic properties such as biochemical oxygen demand (BOD), chemical oxygen demand (COD), ammonia (NH3-N), total dissolved substances (TDS), total alkalinity (TA), and total hardness (TH) by training on WW spectral reflectance in the visible to near-infrared spectrum (400–2000 nm). The dataset contains samples of spectral reflectance intensity, which were the inputs, and the WW parameter levels (BOD, COD, NH3-N, TDS, TA, and TH), which were the outputs. Various NN model configurations were evaluated in terms of regression model fitness. The mean-absolute-error (MAE) was used as the metric for training and testing the NN models, and the coefficient of determination (R2) between the model predictions and true values was also computed to measure how well the NN models predict the true values. The highest R2 (0.994 for training set and 0.973 for testing set) and lowest MAE (0.573 mg/L BOD, 6.258 mg/L COD, 0.369 mg/L NH3-N, 6.98 mg/L TDS, 2.586 m/L TA, and 0.014 mmol/L TH) were achieved when NN models were configured for single-variable output compared to multiple-variables output. Hyperparameter grid-search and k-fold cross-validation improved the NN model prediction performance. With online spectral measurements, the trained neural network model can provide non-contact and real-time estimation of WW quality at minimum estimation error.
      Citation: Clean Technologies
      PubDate: 2023-09-27
      DOI: 10.3390/cleantechnol5040059
      Issue No: Vol. 5, No. 4 (2023)
  • Clean Technol., Vol. 5, Pages 1203-1213: Evaluation of the Effectiveness
           of Treatments to Remove Per- and Polyfluoroalkyl Substances from
           Water—Are We Using the Right Approach' Proposal of a Paradigm Shift
           from “Chemical Only” towards an Integrated Bio-Chemical

    • Authors: Marco Carnevale Miino, Taťána Halešová, Tomáš Macsek, Jakub Raček, Petr Hlavínek
      First page: 1203
      Abstract: Per- and polyfluoroalkyl substances (PFASs) have been under intense investigation by the scientific community due to their persistence in the environment and potentially hazardous effects on living organisms. In order to tackle the presence of these compounds in water, to date, the research has been strongly focused on the evaluation of the effectiveness of different types of technologies. Considering the extreme complexity of the matter of PFASs and our relatively low knowledge in this topic, the following question arises: is the “chemical only” approach that is followed for evaluating the effectiveness of technologies for PFAS removal from water reliable enough' In this work, some limitations of the present approach are discussed, highlighting the reasons why it cannot be considered a reliable tool to correctly estimate the effectiveness of technology when referring to emerging compounds such as PFASs. Bioassays can play a key role in moving towards an integrated bio-chemical evaluation (chemical analysis and ecotoxicological evaluation), which is strongly encouraged. This represents the only way to completely characterize a water matrix and fully evaluate the impact of technologies when dealing with micropollutants in water, such as PFASs. Future research should focus on defining an optimal battery of bioassays that specifically fit to best represent changes in water quality in terms of short- and long-term impacts on living organisms.
      Citation: Clean Technologies
      PubDate: 2023-09-28
      DOI: 10.3390/cleantechnol5040060
      Issue No: Vol. 5, No. 4 (2023)
  • Clean Technol., Vol. 5, Pages 1214-1234: Assessing the Sustainable
           Potential of Corrugated Board-Based Bundle Packaging of PET Bottles: A
           Life Cycle Perspective—A Case Study

    • Authors: Roman Jannes, Pieter Vanhauwermeiren, Peter Slaets, Marc Juwet
      First page: 1214
      Abstract: Large amounts of PET bottles are used worldwide as primary packaging for numerous liquids, including water and soft drinks. In many cases, between two and eight of such bottles are bundled for transport and sales using plastic collation shrink film. This study evaluates paper-based alternatives for plastic bundling material using a life cycle assessment (LCA) of four different types of bundle packaging: LDPE shrink film, recycled Low-Density Polyethylene (rLDPE) shrink film, Ecogrip (existing paper-based bundle packaging) and Ecobundle (new paper-based bundle packaging). The study focuses on the case of bundling six bottles of 1.5 L of sparkling water. The most environmentally friendly option is identified, taking into consideration the material usage, effects on human health and effects on the biosphere. It is concluded that the new corrugated board-based bundling method (Ecobundle) is very promising. Further optimization of the design, minimization of material, improved choice of materials and improved design of the production machinery may result in a corrugated board performing even better than rLDPE shrink film in terms of the global warming potential.
      Citation: Clean Technologies
      PubDate: 2023-10-13
      DOI: 10.3390/cleantechnol5040061
      Issue No: Vol. 5, No. 4 (2023)
  • Clean Technol., Vol. 5, Pages 1235-1247: Delipidation of Chicken Feathers
           by Lipolytic Bacillus Species Isolated from River-Borne Sediments

    • Authors: Tariro Shiri, Nonso E. Nnolim, Uchechukwu U. Nwodo
      First page: 1235
      Abstract: Though the keratin content of chicken feathers is being explored for many potential uses, the crude lipid content of the biomass significantly hinders the valorization processes. Therefore, this study explored the potential of bacteria isolated from sediment for lipolytic properties. Sediment-associated strains were evaluated for lipolytic activity on tween 80–peptone agar. The best lipolytic bacterium was used to break down the lipid content of chicken feathers. The results showed that out of six bacterial strains with variable lipolytic activity, strain TTs1 showed the largest zone of precipitate around the colony, which is why it was selected and identified as Bacillus sp. TTs1. The maximum lipase production of 1530.5 U/mL by strain TTs1 was achieved at 96 h post-fermentation, with optimal process conditions of initial pH (10), incubation temperature (45 °C), agitation speed (140 rpm), inoculum size (2% v/v) and tween 80 (10% v/v). The total free fatty acid (0.58%) was liberated from chicken feathers at a concentration of 6% (w/v). Crude fat extraction from both untreated and TTs1-pretreated chicken feathers showed fat contents of 2.1 ± 0.42% and 0.92 ± 0.13%, respectively. The findings of this study highlight the biotechnological relevance of strain TTs1 in lipase production and the sustainable delipidation of lipid-rich bioresources.
      Citation: Clean Technologies
      PubDate: 2023-10-18
      DOI: 10.3390/cleantechnol5040062
      Issue No: Vol. 5, No. 4 (2023)
  • Clean Technol., Vol. 5, Pages 1248-1268: ZnO for Photoelectrochemical
           Hydrogen Generation

    • Authors: Dina Bakranova, David Nagel
      First page: 1248
      Abstract: The rise in the Earth’s surface temperature on an annual basis has stimulated scientific and engineering interest in developing and implementing alternative energy sources. Besides cost, the main requirements for alternative energy sources are renewability and environmental friendliness. A prominent representative that allows the production of “green” energy is the conversion of solar photons into a practical energy source. Among the existing approaches in solar energy conversion, the process of photoelectrochemical (PEC) hydrogen extraction from water, which mimics natural photosynthesis, is promising. However, direct decomposition of water by sunlight is practically impossible since water is transparent to light waves longer than 190 nm. Therefore, applying a photoelectrochemical process using semiconductor materials and organic compounds is necessary. Semiconductor materials possessing appropriately positioned valence and conduction bands are vital constituents of photoelectrodes. Certain materials exhibit semiconductor characteristics that facilitate the reduction-oxidation (RedOx) reaction of water (H2O) under specific circumstances. ZnO holds a unique position in the field of photocatalysis due to its outstanding characteristics, including remarkable electron mobility, high thermal conductivity, transparency, and more. This article offers an overview of studies exploring ZnO’s role as a photocatalyst in the generation of hydrogen from water.
      Citation: Clean Technologies
      PubDate: 2023-10-20
      DOI: 10.3390/cleantechnol5040063
      Issue No: Vol. 5, No. 4 (2023)
  • Clean Technol., Vol. 5, Pages 1269-1286: A Green Approach to Valorizing
           Abundant Aquatic Weeds for Nutrient-Rich Edible Paper Sheets Production in

    • Authors: Sharmin Suraiya, Suraiya Afrin Bristy, Md. Sadek Ali, Anusree Biswas, Md. Rasal Ali, Monjurul Haq
      First page: 1269
      Abstract: The rapid and unprecedented expansion of the global population highlights concerns about the sufficiency of food resources to sustain this growth. This study investigates and substantiates the feasibility of renewable food resources in order to meet the nutritional requirements of consumers. Three edible aquatic weeds, helencha (Enhydra fluctuans), malancha (Alternanthera philoxeroides), and kalmi (Ipomoea aquatica), were used to produce edible paper sheets. The composition of the raw aquatic weeds and paper sheet samples was analyzed, including the proximate composition, amino acid content, minerals and heavy metal contents, and bioactive compounds. The dried raw aquatic weeds and paper sheets showed similar proximate compositions, with carbohydrates being the highest component (50.38–64.63%), followed by crude protein (15.25–19.13%), ash (9.30–15.88%), and lipid (1.55–3.43%). The raw weeds and paper sheets were rich in essential minerals like Na, Ca, and Zn with contents ranging from 27.7 mg/100 g to 30.4 mg/100 g, 126.8 mg/100 g to 489.65 mg/100 g, and 4.5 mg/100 g to 16.3 mg/100 g, respectively. Acceptable levels of heavy metals, including Ni, Pb, and Cu, were found. The paper sheets contained seven essential and eight non-essential amino acids. Among the essential amino acids, the phenylalanine content was the highest at 2735.9 mg/100 g in E. fluctuans paper sheets, followed by methionine at 2377.29 mg/100 g in the raw E. fluctuans and histidine at 1972.6 mg/100 g in E. fluctuans paper sheets. A. philoxeroides sheets showed the highest total amino acid content (16,146.81 mg/100 g), while I. aquatica showed the lowest (13,118.67 mg/100 g). The aquatic weed paper sheets were rich in bioactive compounds, and the numbers in E. fluctuans, A. philoxeroides, and I. aquatica paper sheets were 31, 33, and 40, respectively. There were no significant changes in the nutritional content of the aquatic weeds in paper sheet form compared with the raw weeds, which suggests promising prospects for their production and consumption as a source of nutrition and bioactive compounds.
      Citation: Clean Technologies
      PubDate: 2023-10-23
      DOI: 10.3390/cleantechnol5040064
      Issue No: Vol. 5, No. 4 (2023)
  • Clean Technol., Vol. 5, Pages 1287-1303: Transient Behavior Analysis of
           Microgrids in Grid-Connected and Islanded Modes: A Comparative Study of
           LVRT and HVRT Capabilities

    • Authors: Abrar Shahriar Pramanik, Saeed Sepasi
      First page: 1287
      Abstract: Microgrids, with integrated PV systems and nonlinear loads, have grown significantly in popularity in recent years, making the evaluation of their transient behaviors in grid-connected and islanded operations paramount. This study examines a microgrid’s low-voltage ride-through (LVRT) and high-voltage ride-through (HVRT) capabilities in these operational scenarios. The microgrid’s behavior was analyzed using both electromagnetic transient (EMT) and RMS simulation methods. Two operational modes, grid-connected and islanded, were considered. A three-phase diesel generator acted as a reference machine in islanded mode. Findings highlighted distinct behaviors in the two operational modes. The EMT simulation revealed in-depth characteristics of electrical parameters, showing high-frequency oscillations more precisely than the RMS simulation. Additionally, the transient recovery times were longer in islanded mode compared to grid-connected mode. The EMT simulation offers a more detailed portrayal of transient behaviors than the RMS simulation, especially in capturing high-frequency disturbances. However, its completion time becomes significantly extended with longer simulation durations. Microgrids showcase distinct transient behaviors in grid-connected versus islanded modes, especially in LVRT and HVRT scenarios. These findings are critical for the design and operation of modern microgrids.
      Citation: Clean Technologies
      PubDate: 2023-11-10
      DOI: 10.3390/cleantechnol5040065
      Issue No: Vol. 5, No. 4 (2023)
  • Clean Technol., Vol. 5, Pages 1304-1343: Poly(lactic acid) and Its Blends
           for Packaging Application: A Review

    • Authors: Stefano De Luca, Daniel Milanese, Duccio Gallichi-Nottiani, Antonella Cavazza, Corrado Sciancalepore
      First page: 1304
      Abstract: Biopolymers obtained from renewable resources are an interesting alternative to conventional polymers obtained from fossil resources, as they are sustainable and environmentally friendly. Poly(lactic acid) (PLA) is a biodegradable aliphatic polyester produced from 100% renewable plant resources and plays a key role in the biopolymer market, and is experiencing ever-increasing use worldwide. Unfortunately, this biopolymer has some usage limitations when compared with traditional polymers; therefore, blending it with other biopolymers, such as poly(butylene succinate) (PBS), poly(butylene succinate-co-butylene adipate) (PBSA), poly(butylene adipate-co-butylene terephthalate) (PBAT) and different poly(hydroxyalkanoates) (PHA), is considered an interesting method to improve it significantly, customize its properties and extend the range of its applications. The following review highlights, in its first part, the physico-chemical and mechanical properties of PLA in comparison to the other biopolymers listed above, highlighting the various drawbacks of PLA. The second part of the review deals with recent developments, results, and perspectives in the field of PLA-based blends.
      Citation: Clean Technologies
      PubDate: 2023-11-10
      DOI: 10.3390/cleantechnol5040066
      Issue No: Vol. 5, No. 4 (2023)
  • Clean Technol., Vol. 5, Pages 791-827: Offshore Electrical Grid Layout
           Optimization for Floating Wind—A Review

    • Authors: Magnus Daniel Kallinger, José Ignacio Rapha, Pau Trubat Casal, José Luis Domínguez-García
      First page: 791
      Abstract: Electrical grid layout optimization should consider the placements of turbines and substations and include effects such as wake losses, power losses in cables, availability of different cable types, reliability-based power losses and operational/decommissioning cost besides the initial investment cost. Hence, optimizing the levelized cost of energy is beneficial capturing long-term effects. The main contribution of this review paper is to identify the current works and trends on electrical layout optimization for offshore wind farms as well as to analyze the applicability of the found optimization approaches to commercial-scale floating wind farms which have hardly been investigated so far. Considering multiple subproblems (i.e., micrositing and cabling), simultaneous or nested approaches are advantageous as they avoid sequential optimization of the individual problems. To cope with this combinatorial problem, metaheuristics seems to offer optimal or at least close-to-optimal results while being computationally much less expensive than deterministic methods. It is found that floating wind brings new challenges which have not (or only insufficiently) been considered in present optimization works. This will also be reflected in a higher complexity and thus influence the suitability of applicable optimization techniques. New aspects include the mobility of structures, the configurations and interactions of dynamic cables and station-keeping systems, the increased likelihood of prevailing heterogeneous seabeds introducing priority zones regarding anchor and riser installation, the increased importance of reliability and maintainability due to stricter weather limits, and new floating specific wind farm control methods to reduce power losses. All these facets are crucial to consider when thoroughly optimizing the levelized cost of energy of commercial-scale floating offshore wind farms.
      Citation: Clean Technologies
      PubDate: 2023-06-26
      DOI: 10.3390/cleantechnol5030039
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 828-838: Metal-Supported TiO2/SiO2
           Core-Shell Nanosphere Photocatalyst for Efficient Sunlight-Driven Methanol

    • Authors: M. R. Karimi Estahbanati, Thuy-Dung Vu, Trong-On Do, Zahra Nayernia, Maria C. Iliuta
      First page: 828
      Abstract: The development of novel and active photocatalysts to industrialize photocatalysis technology is still a challenging task. In this work, a novel method is presented to prepare TiO2/SiO2 NSs by covering SiO2 nanospheres (NSs) with titanate-nanodiscs (TNDs) followed by calcination. In this regard, SiO2 NSs are first synthesized and then TNDs are deposited on the SiO2 NSs using a layer-by-layer deposition technique. The morphology of the prepared samples is analyzed via SEM and TEM analyses before and after the deposition. The analysis of metal (Cu, Pt, and Ni) loading on calcined TNDs/SiO2 NSs reveals the highest specific surface area (109 m2/g), absorption wavelength extension (up to 420 nm), and photocatalytic activity for the Cu-loaded sample. In addition, studying the effect of metal content shows that loading 3% Cu leads to the highest photocatalytic activity. Finally, it is demonstrated that H2S treatment can improve the photocatalytic activity by around 15%. These findings suggest the calcined TNDs/SiO2 NSs are a versatile photocatalyst with potential applications in other processes such as hydrogen production and CO2 valorization.
      Citation: Clean Technologies
      PubDate: 2023-06-27
      DOI: 10.3390/cleantechnol5030040
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 839-851: Mercury Removal from Mining
           Wastewater by Phytoaccumulation in Autochthonous Aquatic Plant Species

    • Authors: Franco Hernan Gomez, Maria Cristina Collivignarelli, Ahmed Mohammad Nafea Masoud, Marco Carnevale Miino, Kelly Cristina Torres, Jesus Antonio Quintero, Sabrina Sorlini, Mentore Vaccari
      First page: 839
      Abstract: Mining wastewater (MWW) can contain mercury in high concentrations. In this study, four autochthonous aquatic plant species (Eichhornia Crassipes—EC, Marsilea Quadrifolia—MQ, Ludwigia Helminthorrhiza—LH, and Lemna Minor—LM) were identified and tested for phytoaccumulation of total mercury (THg). To better study the accumulation phenomenon and macrophyte responses, this work has been divided into three phases, and pilot-scale reactors have been used to simulate real conditions. The results highlighted that, in case of 15 µgTHg,fed, the bioconcentration factor (BCF) was significantly higher in EC (19.04) and LH (18.41) with respect to MQ and LM (almost six times and two times higher, respectively). EC granted the best results in terms of THg accumulation (50.90%) and lower evapotranspiration of THg phenomenon with respect to LH. A significant decrease of the BCF (from 23.45 to 21.98) and an increase of the TF (from 0.23 up to 0.73) after 42 d highlighted that a breaking-time in terms of THg accumulation was reached due to the deterioration of the roots. In terms of the kinetics of THg removal by bioaccumulation, an HLT of 69.31 d was found, which is more than the breaking-time of the EC system, proving that a periodic replacement of exhausted macrophytes is required to obtain a higher percentage of THg removal.
      Citation: Clean Technologies
      PubDate: 2023-06-27
      DOI: 10.3390/cleantechnol5030041
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 852-865: Treatment of Dark Humic Water Using
           Photocatalytic Advanced Oxidation (PAO) Processes under Visible and UV

    • Authors: Alexandra Gordon, Mark C. Leaper, Herman Potgieter, Darlington Ashiegbu, Vusumuzi Sibanda
      First page: 852
      Abstract: The aim of the study was to investigate the application of photocatalytic advanced oxidation (PAO) for the treatment of water contaminated with dark humic material from fynbos biome plants, which cannot be treated by conventional methods. The study used a fynbos species (Aspalathus linearis) to create a model wastewater that was compared with a brew made from black tea (Camellia sinensis). Two photocatalysts (TiO2 and ZnO) and three light sources (natural, halogen light, and UV light) were tested, with and without hydrogen peroxide. The treatment of the two teas by only photolysis was observed to be minimal. The study found that natural sunlight was not effective, but a combination of ZnO and halogen lamp exhibited the best performance, with a 60% degradation in 20 min under solar irradiation. The optimum catalyst concentration was identified as 10 g/L for both photocatalysts. The influence of some process parameters showed that a combination of an optimum dose of 5 mM H2O2 and solar radiation improved the performance of TiO2 from 16 to 47%. The photocatalytic reaction data were fitted to the pseudo first and second-order kinetic models in order to exploit the kinetic process of the photo-destruction reaction. The kinetic fits showed that the degradation reaction better adhered to the second-order kinetic model when only ZnO and solar radiation were applied, regardless of the tea type employed. The application of PAO in this novel and cost-effective way has potential for the abatement of contaminated water to potable water. The use of heterojunction photocatalysts could be explored in future research to further improve the process.
      Citation: Clean Technologies
      PubDate: 2023-07-06
      DOI: 10.3390/cleantechnol5030042
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 866-880: Elementary Steps in Steady State
           Kinetic Model Approximation for the Homo-Heterogeneous Photocatalysis of

    • Authors: Yuval Shahar, Giora Rytwo
      First page: 866
      Abstract: Elucidating physicochemical processes in the degradation of pollutants may optimize their removal from water sources. Although the photodegradation of carbamazepine (CBZ) in Advanced Oxidation Processes (AOPs) has been widely studied, there is no detailed report on the elementary steps of the kinetics. This study proposes a set of elementary steps for the AOP of CBZ, combining short-wave ultraviolet radiation (UVC), a homogeneous reagent (H2O2), and a heterogeneous catalyst (TiO2), which includes the excitation of both reagents/catalysts by UVC photons, the adsorption of CBZ by the excited TiO2, or its oxidation by hydroxyl radicals. Assuming the steady-state approximation on the intermediate products (excited TiO2, CBZ-excited TiO2 complex, and hydroxyl radicals) leads to rate laws for the degradation of CBZ, in which UVC radiation, TiO2, and H2O2 are pseudo-first-order at all concentrations or intensities and have no direct influence on CBZ pseudo-order, whereas CBZ shifts from pseudo-first-order at low concentrations to pseudo-zero-order at high concentrations. Several experiments to test the mechanism were conducted by varying CBZ, H2O2, and TiO2 concentrations and UVC radiation intensities. The measured results indeed fit the suggested mechanism for the first three, but the irradiation intensity appears to shift the CBZ influence from pseudo-second- to pseudo-first-order with increased intensities. Part of the elementary steps were changed to fit the results.
      Citation: Clean Technologies
      PubDate: 2023-07-06
      DOI: 10.3390/cleantechnol5030043
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 881-900: Toward Efficient Recycling of
           Vanadium Phosphate-Based Sodium-Ion Batteries: A Review

    • Authors: Aleksandr Sh. Samarin, Alexey V. Ivanov, Stanislav S. Fedotov
      First page: 881
      Abstract: Sodium-ion batteries (SIBs) have demonstrated noticeable development since the 2010s, being complementary to the lithium-ion technology in predominantly large-scale application niches. The projected SIB market growth will inevitably lead to the generation of tons of spent cells, posing a notorious issue for proper battery lifecycle management, which requires both the establishment of a regulatory framework and development of technologies for recovery of valuable elements from battery waste. While lithium-ion batteries are mainly based on layered oxides and lithium iron phosphate chemistries, the variety of sodium-ion batteries is much more diverse, extended by a number of other polyanionic families (crystal types), such as NASICON (Na3V2(PO4)3), Na3V2(PO4)2F3−yOy, (0 ≤ y ≤ 2), KTiOPO4-type AVPO4X (A—alkali metal cation, X = O, F) and β-NaVP2O7, with all of them relying on vanadium and phosphorous—critical elements in a myriad of industrial processes and technologies. Overall, the greater chemical complexity of these vanadium-containing phosphate materials highlights the need for designing specific recycling approaches based on distinctive features of vanadium and phosphorus solution chemistry, fine-tuned for the particular electrodes used. In this paper, an overview of recycling methods is presented with a focus on emerging chemistries for SIBs.
      Citation: Clean Technologies
      PubDate: 2023-07-06
      DOI: 10.3390/cleantechnol5030044
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 901-920: Comparative Life Cycle Assessment
           of Different Portland Cement Types in South Africa

    • Authors: Oluwafemi E. Ige, Oludolapo A. Olanrewaju
      First page: 901
      Abstract: Cement has long been recognized as an energy- and emission-intensive construction material. Cement production has recently experienced significant growth despite its high energy consumption, resource usage, and carbon emissions. This study aims to assess and compare the life cycle assessment (LCA) of traditional Portland cement (CEM I) to those of three blended cement types (CEM II/B-L, CEM II/B-V, and CEM III/A), which assume mature technologies for reducing carbon emissions in South Africa, using LCA in compliance with ISO/TS 14071 and 14072. As its scope, the study employs the “cradle to gate” method, which considers the raw materials, fuel usage, electricity, transportation, and clinkering stages, using 1 kg of cement as the functional unit. The LCA analyses were performed using SimaPro software developed by PRé Consultants, Amersfoort, Netherlands and impact assessments were conducted using the ReCiPe 2016 v1.04 midpoint method in order to compare all 18 impact categories of 1 kg of cement for each cement type. The assessment results show reductions in all impact categories, ranging from 7% in ozone depletion and ionizing radiation (CEM II/B-L) to a 41% reduction in mineral resource scarcity (CEM III/A). The impacts of global warming were reduced by 14% in the case of CEM II/B-L, 29% in the case of CEM II/B-V and 35% in the case of CEM III/A. The clinkering process was identified as the primary cause of atmospheric impacts, while resource depletion impacts were attributed to raw materials, fuels, and electricity processes, and toxicity impacts were primarily caused by raw materials. Alternative materials, like fly ash and ground granulated blast furnace slag (GGBFS), can significantly help to reduce environmental impacts and resource consumption in the cement industry.
      Citation: Clean Technologies
      PubDate: 2023-07-13
      DOI: 10.3390/cleantechnol5030045
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 921-933: Mathematical Modeling of Particle
           Terminal Velocity for Improved Design of Clarifiers, Thickeners and
           Flotation Devices for Wastewater Treatment

    • Authors: Dario Friso
      First page: 921
      Abstract: The prediction of the terminal velocity of a single spherical particle is essential to realize mathematical modeling useful for the design and adjustment of separators used in wastewater treatment. For non-spherical and non-single particles, terminal velocity can be traced back to that of single spheres using coefficients and Kynch’s theory, respectively. Because separation processes can involve small or large particles and can be carried out using gravity, as with clarifiers/thickeners, or by centrifugation in centrifuges where the acceleration can exceed 10,000× g, the Reynolds number of the particle can be highly variable, ranging from 0.1 to 200,000. The terminal velocity depends on the drag coefficient, which depends, in turn, on the Reynolds number containing the terminal velocity. Because of this, to find the terminal velocity formula, it is preferable to look first for a relationship between the drag coefficient and the Archimedes number which does not contain the terminal velocity. Formulas already exist expressing the relationship between the drag coefficient and the Archimedes number, from which the relationship between the terminal velocity and the Archimedes number may be derived. To improve the accuracy obtained by these formulas, a new relationship was developed in this study, using dimensional analysis, which is valid for Reynolds number values between 0.1 and 200,000. The resulting mean relative difference, compared to the experimental standard drag curve, was only 1.44%. This formula was developed using the logarithms of dimensionless numbers, and the unprecedented accuracy obtained with this method suggested that an equally accurate formula for the drag coefficient could also be obtained with respect to the Reynolds number. Again, the resulting level of accuracy was unprecedentedly high, with a mean relative difference of 1.77% for Reynolds number values between 0.1 and 200,000.
      Citation: Clean Technologies
      PubDate: 2023-07-17
      DOI: 10.3390/cleantechnol5030046
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 934-960: Remediation of Heavy Metals Using
           Biomass-Based Adsorbents: Adsorption Kinetics and Isotherm Models

    • Authors: Okon-Akan Omolabake Abiodun, Oluwasogo Oluwaseun, Olaoye Kayode Oladayo, Omoogun Abayomi, Akpowu Arubi George, Emmanuel Opatola, Robinson Friday Orah, Efe Jeffery Isukuru, Ifunanya Chiamaka Ede, Oluwadara Temitayo Oluwayomi, Jude A. Okolie, Ibrahim Asiata Omotayo
      First page: 934
      Abstract: This study aims to comprehensively investigate the current advances in water treatment technologies for the elimination of heavy metals using biomass-based adsorbents. The enhancement of adsorption capacity in biomass materials is achieved through surface modification, which increases their porosity and surface area. The study therefore focuses on the impact of different surface modification techniques on the adsorption capacity, as well as the evaluation of adsorptive removal techniques and the analysis of various isotherm and kinetics models applied to heavy metal contaminants. The utilization of kinetic and isotherm models in heavy metal sorption is crucial as it provides a theoretical background to understand and predict the removal efficiency of different adsorbent materials. In contrast to previous studies, this research examines a wide range of adsorbent materials, providing a comprehensive understanding of their efficacy in removing heavy metals from wastewater. The study also delves into the theoretical foundations of the isotherm and kinetics models, highlighting their strengths, limitations, and effectiveness in describing the performance of the adsorbents. Moreover, the study sheds light on the regenerability of adsorbents and the potential for their engineering applications. Valuable insights into the state-of-the-art methods for heavy metal wastewater cleanup and the resources required for future developments were discussed.
      Citation: Clean Technologies
      PubDate: 2023-07-28
      DOI: 10.3390/cleantechnol5030047
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 961-972: Eco-Friendly Cement Mortar with
           Wastewater Treatment Plant Sludge Upcycling

    • Authors: Thais Theomaris Grabowski, Juliana Martins Teixeira de Abreu Pietrobelli, Ramiro José Espinheira Martins
      First page: 961
      Abstract: This study aimed to investigate the technical feasibility of replacing cement in mortar production with sludge generated in wastewater treatment plants (WWTPs), prepared using different treatments. The sludge used in the experiments was processed using four different methods to investigate the effect of processing on the mechanical strength of the specimens. The sludge was then mixed with mortar in different proportions, and samples were produced for flexural and compressive strength tests. The results showed that specimens with 7% sludge from the burned treatment exhibited the highest resistance, surpassing the standard. Specimens with sludge from the drying treatments showed similar results. This study found that using sludge in mortar production could lead to energy savings compared to traditional cement production methods. Moreover, the incorporation of sludge resulted in mortars that met the specifications of the EN 998-1:2018 standard, thereby indicating their technical feasibility. Therefore, this study demonstrated the potential of using sludge from WWTPs as a substitute for cement in mortar production, which could contribute to the reduction in the environmental impacts caused by civil construction and the development of sustainable alternatives for the disposal of sludge generated in WWTPs.
      Citation: Clean Technologies
      PubDate: 2023-08-02
      DOI: 10.3390/cleantechnol5030048
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 973-996: Fluoride Removal and Recovery from
           Water Using Reverse Osmosis and Osmotic Membrane Crystallization

    • Authors: Wuhib Zeine Ousman, Esayas Alemayehu, Patricia Luis
      First page: 973
      Abstract: Fluoride is a concern for human health at high concentrations, but it is also a valuable compound with multiple applications. Thus, having a system that gives the opportunity to remove and recover this valuable element from water is highly interesting. Reverse osmosis (RO) is a promising technology in the removal of fluoride from water. Nevertheless, the residual retentate highly concentrated in fluoride is still a concern. The aim of this study was to evaluate the performance of an integrated process consisting of RO and membrane crystallization to remove fluoride from water and to recover it as a pure fluoride salt. Pure water permeability and fluoride rejection of a commercial RO membrane was tested under different conditions. In addition, the performance of an osmotic membrane crystallization setup was evaluated, considering the effect caused by the flow rates and the concentration of both the feed and the osmotic solution on the mass transfer coefficient. The crystallization process allowed the production of pure NaF crystals with octahedral morphology with a face-centered cubic crystal system.
      Citation: Clean Technologies
      PubDate: 2023-08-07
      DOI: 10.3390/cleantechnol5030049
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 997-1011: Prospects of Waste Incineration
           for Improved Municipal Solid Waste (MSW) Management in Ghana—A

    • Authors: Noah Yakah, Mahrokh Samavati, Augustine Akuoko Kwarteng, Andrew Martin, Anthony Simons
      First page: 997
      Abstract: The per capita municipal solid waste (MSW) generation per day in Ghana is estimated to be 0.47 kg/person/day, which translates to over 14,000 tonnes of solid waste generation daily. The disposal and management of this amount of solid waste has been challenging worldwide, and in Ghana, this is evident with the creation of unsanitary dumping sites scattered across most communities in the country, especially urban communities. The indiscriminate disposal of solid waste in Ghana is known to cause flooding, the pollution of water bodies, and the spread of diseases. The purpose of this review is to highlight the prospects of waste incineration with energy recovery as a waste-to-energy (WtE) technology which has contributed immensely to the disposal and management of MSW in nations worldwide (especially developed ones). The review indicates that waste incineration with energy recovery is a matured waste-to-energy technology in developed nations, and there are currently about 492 waste incineration plants in operation in the EU, over 77 in operation in about 25 states in the USA, and about 1900 in operation in Japan. Waste incineration with energy recovery is also gradually gaining prominence in developing nations like China, Brazil, Bangladesh, Nigeria, Indonesia, and Pakistan. The adoption of waste incineration with energy technology can reduce Ghana’s overdependence on fossil fuels as primary sources of energy. It is, however, recommended that a techno-economic assessment of proposed waste incineration facilities is performed considering the MSW generated in Ghana. Additionally, it is also recommended that the possibility of incorporating the use of artificial intelligence technology into the management of MSW in Ghana be investigated.
      Citation: Clean Technologies
      PubDate: 2023-08-10
      DOI: 10.3390/cleantechnol5030050
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 1012-1027: Influence of Dimple Diameter and
           Depth on Heat Transfer of Impingement-Cooled Turbine Leading Edge with
           Cross-Flow and Dimple

    • Authors: Bin Qu, Zilong Chen, Dengke He, Fei Zeng, Youfu Song, Yuqing Ouyang, Lei Luo
      First page: 1012
      Abstract: Today, impingement cooling structures with dimples can effectively ease the burden of turbine blades. This paper investigates the effect of dimple diameter and depth on the heat transfer of the target surface on a laminar-cooled turbine blade with a cross-flow and dimple numerically to find the mechanism behind it so that the dimple can be better used in turbine cooling. The commercial software ANSYS 19.2 and a baseline (BSL) turbulence model is used during the numerical computation. In this paper, the cross-flow Reynolds number varies from 15,000 to 60,000, while the jet Reynolds number remains at 30,000. When the cross-flow Reynolds number changes, due to the location change in vortexes generated inside or around the dimple, the two dimple parameters affect heat transfer differently. When the cross-flow Reynolds number is lower than the jet Reynolds number, dimples with smaller diameters and depths lead to better heat transfer performance. When the cross-flow Reynolds number exceeds the jet Reynolds number, dimples with bigger diameters and depths result in better heat exchange performance. The results also indicate that, while the dimple diameters remain constant, the rise of the cross-flow Reynolds number enhances the heat transfer of the dimple structure.
      Citation: Clean Technologies
      PubDate: 2023-08-18
      DOI: 10.3390/cleantechnol5030051
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 1028-1043: Extraction and Characterization
           of Cellulose Obtained from Banana Plant Pseudostem

    • Authors: Rosa E. A. Nascimento, Mónica Carvalheira, João G. Crespo, Luísa A. Neves
      First page: 1028
      Abstract: Each year, the amount of residue generated from food production increases, caused by the continuous population growth. Banana is one of the most consumed fruits in the world, with an annual production of 116.78 million tonnes. However, just 12 wt% of the plant, corresponding to the bunch, is effectively used. After the bunch is harvested, the rest of the plant is disposed of as residue, the pseudostem (PS) being the main constituent. Aiming to give an added-value application to the PS, this work is focused on the extraction of cellulose from this waste. For this, three different fractions of PS particles—a non-classified fraction (milled but without sieving), a fine fraction (≤180 μm), and a coarse fraction (≥2000 μm)—and three extraction methods—alkaline-acid hydrolysis, enzymatic hydrolysis, and TEMPO oxidation—were studied to determine the most promising method for the cellulose extraction from the PS. The alkaline-acid hydrolysis samples presented a higher number of amorphous compounds, resulting in lower crystallinity (13.50% for the non-classified fraction). The TEMPO-oxidation process, despite allowing the highest cellulose extraction yield (25.25 ± 0.08% on a dried basis), resulted in samples with lower thermal stability (up to 200 °C). The most promising extraction method was enzymatic, allowing the extraction of 14.58 ± 0.30% of cellulose (dried basis) and obtaining extracts with the highest crystallinity (68.98% for the non-classified fraction) and thermal stability (until 250 °C).
      Citation: Clean Technologies
      PubDate: 2023-08-29
      DOI: 10.3390/cleantechnol5030052
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 1044-1066: Assessing the Sustainability of
           the Most Prominent Type of Marine Diesel Engines under the Implementation
           of the EEXI and CII Regulations

    • Authors: Dionysios Polemis, Michael Boviatsis, Stefanos Chatzinikolaou
      First page: 1044
      Abstract: The wide spread of the Diesel engine has been instrumental in the development of modern shipping. Marine Diesel engines dominate today as an option for the propulsion of commercial ships. While replacing Diesel engines with alternative propulsion engines is difficult to achieve, companies, in light of the new EEXI regulations, are turning to improvements, such as operating at lower rotational speeds, higher maximum combustion pressures, and more efficient overcrowding systems. Τhe purpose of this research paper is (i) to present the basic operating principles of marine Diesel engines, (ii) to study the main differences between electronically controlled Diesel engines and their mechanically controlled counterparts, and (iii) to evaluate their performance under newly introduced IMO’s EEXI regulations. Thus, after comparing Wärtsilä RTA and WinGD WX, the paper concluded that WinGD WX, being electronically controlled, will perform more effectively under new EEXI regulations, as it offers (i) reduced fuel consumption in low-load mode, (ii) zero-smoke emission at all operating speeds, (iii) very stable operation at low speed, (iv) more straightforward engine setup leading to less maintenance, (v) more extended periods between maintenance, mainly due to better load distribution between cylinders and more perfect combustion. From a regulatory perspective, the new limitations installed by the newly implemented EEXI and CII regulations will cause fewer implications in electronically controlled engines, while from an economic standpoint, the electronically controlled engines decrease OPEX and require fewer personnel, due to their efficiency at low loads and overall flexibility.
      Citation: Clean Technologies
      PubDate: 2023-08-30
      DOI: 10.3390/cleantechnol5030053
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 1067-1079: Use of Automatic Dishwashers and
           Their Programs in Europe with a Special Focus on Energy Consumption

    • Authors: Thomas J. Tewes, Laurence Harcq, Dirk P. Bockmühl
      First page: 1067
      Abstract: Due to the current high awareness and rising energy costs, the energy label of domestic appliances is an important indicator for consumers when buying a dishwasher. However, not all consumers use efficient Eco cycles on a regular basis. When investigating the use of domestic dishwashers and the chosen programs in a survey with 6090 participants from 11 countries in Europe, it turned out that only 25% used Eco cycles regularly while the vast majority of 48% prefer to use Normal/Auto cycles. We also assessed individual energy and water consumption as well as duration and temperature of the programs. Considering the fact that Eco programs are not well accepted due to their duration, our study shows that Short programs, which on average only last about 30 min and consume little energy and water, might be an economical and convenient alternative to the more time-consuming Eco programs. In fact, some Short programs considered in this study proved to consume less energy for a full dishwasher load (0.74 kWh on average) than the standard Eco programs (0.90 kWh on average), especially due to their shorter duration, but it is important to note that, according to the manufacturer, these programs are designed for rather lightly soiled dishes.
      Citation: Clean Technologies
      PubDate: 2023-09-20
      DOI: 10.3390/cleantechnol5030054
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 1080-1114: The Application of UAVs in the
           Evaluation of Thermal Comfort Levels in Buildings Equipped with Internal

    • Authors: Maria Inês Conceição, Eusébio Conceição, António Grilo, Meysam Basiri, Hazim Awbi
      First page: 1080
      Abstract: A greenhouse is used to improve thermal comfort (TC) levels for its occupants in winter conditions using solar radiation, which involves low energy consumption. The aim of this research is the application of unmanned aerial vehicles (UAVs) in the evaluation of thermal comfort levels in buildings equipped with internal greenhouses. The new building design is developed numerically, and a building thermal simulator (BTS) numerical model calculates the indoor environmental variables. A new alternative and expeditious method to measure occupants’ comfort levels using UAV technology is applied using a UAV dynamic simulator (UAV DS). The evolution of the measured variables used for evaluating the predicted mean vote (PMV) is compared using the two numerical methodologies: BTS and UAV DS. In the second one, the mean radiant temperature (MRT) measuring methodology, the floor temperature, the lateral walls’ temperatures, the ceiling temperatures, and the air temperature are applied. In the method presented in this paper, a new building design is developed numerically, which includes a central greenhouse equipped with a semispherical dome, four auditoriums distributed around the central greenhouse, occupant distribution, and a ventilation methodology. The building geometry, the solar radiation on transparent surfaces, the TC, and the UAV mission methods are presented. The results show that, in general, the central greenhouse and the ventilation methodologies provide acceptable TC levels. The UAV monitoring mission, which includes two vehicles, provides good environmental variable replication, particularly when the environmental variables present greater variations. In the auditorium and greenhouse, the ceiling and lateral surface temperatures, respectively, can be used as an MRT approximation. The BTS numerical model is also important for developing buildings using renewable energy sources to improve the TC levels.
      Citation: Clean Technologies
      PubDate: 2023-09-20
      DOI: 10.3390/cleantechnol5030055
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 1115-1139: Coupling a Gas Turbine Bottoming
           Cycle Using CO2 as the Working Fluid with a Gas Cycle: Exergy Analysis
           Considering Combustion Chamber Steam Injection

    • Authors: S. Hamed Fatemi Alavi, Amirreza Javaherian, S. M. S. Mahmoudi, Saeed Soltani, Marc A. Rosen
      First page: 1115
      Abstract: Gas turbine power plants have important roles in the global power generation market. This paper, for the first time, thermodynamically examines the impact of steam injection for a combined cycle, including a gas turbine cycle with a two-stage turbine and carbon dioxide recompression. The combined cycle is compared with the simple case without steam injection. Steam injection’s impact was observed on important parameters such as energy efficiency, exergy efficiency, and output power. It is revealed that the steam injection reduced exergy destruction in components compared to the simple case. The efficiencies for both cases were obtained. The energy and exergy efficiencies, respectively, were found to be 30.4% and 29.4% for the simple case, and 35.3% and 34.1% for the case with steam injection. Also, incorporating steam injection reduced the emissions of carbon dioxide.
      Citation: Clean Technologies
      PubDate: 2023-09-21
      DOI: 10.3390/cleantechnol5030056
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 1140-1158: Performance Analysis of
           Conventional IPMSM and NCPM Based IPMSM

    • Authors: J. Vijaya Kumar, T. Narasimhulu, G. Raja Rao, Surender Reddy Salkuti
      First page: 1140
      Abstract: This paper proposes a NCPM (Nano-composite coated permanent magnets)-based IPMSM (Interior Permanent Magnet Synchronous Motor) electric drive system, especially applicable for electric vehicles (EV). For an EV, an increase in the “T/A (torque per ampere)” condition is highly recommended, as it directly affects the maximum distance run by EV on a single charge. Due to NCPM, a substantial increase in magnetic flux intensity, resistance to corrosion and Curie temperature are observed. As a result, the proposed drive clearly exhibits a higher power to weight ratio. Also, it is capable of delivering higher T/A to the drive system without any considerable change in two important factors of EV: (1) mass and volume of the drive system (2) battery capacity of the drive system. Moreover, NCPM performance is less susceptible to temperature variation, which makes it an appropriate candidate for vehicular applications, where temperature inconsistency could be a common issue during working conditions. Also, NCPM-based IPMSM offers a quicker speed response than conventional IPMSM, thus providing higher acceleration, which is one of the important performance factors for vehicular applications. A vector controlled mathematical model of IPMSM and NCPM-based IPMSM is tested for various speed commands. Also, the NCPM-based IPMSM, in the proposed configuration, is fed from a three-level DCMLI (diode clamped multi-level inverter), as the drive system is considered for medium to high power applications. A comparative performance analysis is carried out between the proposed drive system and a conventional IPMSM-based drive system using MATLAB/SIMULINK to indicate the efficacy of the proposed configuration.
      Citation: Clean Technologies
      PubDate: 2023-09-21
      DOI: 10.3390/cleantechnol5030057
      Issue No: Vol. 5, No. 3 (2023)
  • Clean Technol., Vol. 5, Pages 451-465: Bio Ethanol Production from Rice
           Straw Saccharification via Avicelase Gene in E. coli Recombinant Strain

    • Authors: Mohamed S. Abdel-Salam, Safa S. Hafez, Mohamed Fadel, Shereen A. H. Mohamed, Wafaa K. Hegazy, Bigad E. Khalil
      First page: 451
      Abstract: The most abundant organic carbon source on Earth is cellulosic materials. Its main resources are crop straws which are not commonly used and produce environmental pollution. These resources can be a site of biological hydrolysis to primary sugars by cellulase enzymes, in which avicelase is the most efficient enzyme in the cellulase family. This work aimed to clone the avicelase gene, transfer it to E. coli, optimize its expression, saccharify rice straw to its primary sugars, and ferment it to bioethanol. The avicelase gene was cloned from the Bacillus subtilis strain and cloned into two E. coli (i.e., DH5α and Bl21) strains. The optimized avicelase activity was described by testing the effect of different media and growth conditions including different carbon and nitrogen sources, as well as pHs and shaking or static conditions. Avicelase enzyme was extracted and used to saccharify rice straw. The obtained glucose was subjected to fermentation by Saccharomyces cerevisiae F.307 under an aerobic condition growth for the production of bioethanol. The ethanol yield was 5.26% (v/v), and the fermentation efficiency was 86%. This study showed the ability to clone one of the cellulolytic genes (i.e., avicelase) for the valorization of rice straw for producing renewable energy and bioethanol from cellulolytic wastes such as rice straw.
      Citation: Clean Technologies
      PubDate: 2023-04-03
      DOI: 10.3390/cleantechnol5020023
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 466-483: Efficient Adsorption and Catalytic
           Reduction of Phenol Red Dye by Glutaraldehyde Cross-Linked Chitosan and
           Its Ag-Loaded Catalysts: Materials Synthesis, Characterization and

    • Authors: Chiara Concetta Siciliano, Van Minh Dinh, Paolo Canu, Jyri-Pekka Mikkola, Santosh Govind Khokarale
      First page: 466
      Abstract: In this study, glutaraldehyde cross-linked chitosan support, as well as the catalysts obtained after loading Ag metal (Ag/Chitosan), were synthesised and applied for adsorption and reduction of phenol red dye in an aqueous solution. The Ag/chitosan catalysts were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR) and inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis techniques. The catalytic reduction and adsorption performance of phenol red dye with Ag/chitosan and cross-linked chitosan, respectively, was performed at ambient reaction conditions. The reduction of dye was carried out using sodium borohydride (NaBH4) as the reducing agent, while the progress of adsorption and reduction study was monitored with ultraviolet-visible (UV-vis) spectrophotometry technique. The reduction of the phenol red dye varied with the amount of catalyst, the concentration of NaBH4, Ag metal loading, reaction temperature, phenol red dye concentration and initial pH of the dye solution. The dye solution with a nearly-neutral pH (6.4) allowed efficient adsorption of the dye, while acidic (pH = 4) and alkaline (pH = 8, 11, 13.8) solutions showed incomplete or no adsorption of dye. The reusability of the Ag/chitosan catalyst was applied for the complete reduction of the dye, where no significant loss of catalytic activity was observed. Hence, the applicability of cross-linked chitosan and Ag/catalyst was thus proven for both adsorption and reduction of phenol red dye in an aqueous solution and can be applied for industrial wastewater treatment.
      Citation: Clean Technologies
      PubDate: 2023-04-06
      DOI: 10.3390/cleantechnol5020024
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 484-496: Reduced Mechanism for Combustion of
           Ammonia and Natural Gas Mixtures

    • Authors: Aniket R. Khade, Vijaya D. Damodara, Daniel H. Chen
      First page: 484
      Abstract: A fuel mixture of ammonia and natural gas as a low-carbon alternative for future power generation and transportation is an attractive option. In this work, a 50-species reduced mechanism, NH3NG, suitable for computational fluid dynamics simulations (CFD), is developed for ammonia–natural gas cofiring while addressing important emission issues, such as the formation of nitrogen oxides (NOx), soot, carbon monoxide, and unburnt methane/ammonia. The adoption of reduced mechanisms is imperative not only for saving computer storage and running time but also for numerical convergence for practical applications. The NH3NG reduced mechanism can predict soot emission because it includes soot precursor species. Further, it can handle heavier components in natural gas, such as ethane and propane. The absolute error is 5% for predicting NOx and CO emissions compared to the full Modified Konnov mechanism. Validation with key performance parameters (ignition delay, laminar flame speed, adiabatic temperature, and NOx and CO emissions) indicates that the predictions of the reduced mechanism NH3NG are in good agreement with published experimental data. The average prediction error of 13% for ignition delay is within typical experimental data uncertainties of 10–20%. The predicted adiabatic temperatures are within 1 °C. For laminar flame speed, the R2 between prediction and data is 0.985. NH3NG over-predicts NOx and CO emissions, similar to all other literature methods, but the NOx predictions are closer to the experimental data.
      Citation: Clean Technologies
      PubDate: 2023-04-12
      DOI: 10.3390/cleantechnol5020025
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 497-517: Machine Learning Applications in
           Renewable Energy (MLARE) Research: A Publication Trend and Bibliometric
           Analysis Study (2012–2021)

    • Authors: Samuel-Soma M. Ajibade, Festus Victor Bekun, Festus Fatai Adedoyin, Bright Akwasi Gyamfi, Anthonia Oluwatosin Adediran
      First page: 497
      Abstract: This study examines the research climate on machine learning applications in renewable energy (MLARE). Therefore, the publication trends (PT) and bibliometric analysis (BA) on MLARE research published and indexed in the Elsevier Scopus database between 2012 and 2021 were examined. The PT was adopted to deduce the major stakeholders, top-cited publications, and funding organizations on MLARE, whereas BA elucidated critical insights into the research landscape, scientific developments, and technological growth. The PT revealed 1218 published documents comprising 46.9% articles, 39.7% conference papers, and 6.0% reviews on the topic. Subject area analysis revealed MLARE research spans the areas of science, technology, engineering, and mathematics among others, which indicates it is a broad, multidisciplinary, and impactful research topic. The most prolific researcher, affiliations, country, and funder are Ravinesh C. Deo, National Renewable Energy Laboratory, United States, and the National Natural Science Foundation of China, respectively. The most prominent journals on the top are Applied Energy and Energies, which indicates that journal reputation and open access are critical considerations for the author’s choice of publication outlet. The high productivity of the major stakeholders in MLARE is due to collaborations and research funding support. The keyword co-occurrence analysis identified four (4) clusters or thematic areas on MLARE, which broadly describe the systems, technologies, tools/technologies, and socio-technical dynamics of MLARE research. Overall, the study showed that ML is critical to the prediction, operation, and optimization of renewable energy technologies (RET) along with the design and development of RE-related materials.
      Citation: Clean Technologies
      PubDate: 2023-04-19
      DOI: 10.3390/cleantechnol5020026
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 518-530: Membrane Filtration Applied to the
           Purification of Sugarcane Bagasse Mild Alkaline Extracts

    • Authors: Vincent Oriez, Nga Thi-Thanh Pham, Jérôme Peydecastaing, Philippe Behra, Pierre-Yves Pontalier
      First page: 518
      Abstract: Sugarcane bagasse (SCB), a by-product of the sugar industry, is composed mainly of cellulose, hemicelluloses, and lignin, and can be used to replace petrochemical polymers in various applications. In this work, SCB was treated under mild alkaline conditions with 1.5% NaOH (m:v) and a solid:liquid ratio of 1:20 (m:v) at 60 °C, during 6 h. A 10 kDa polysulfone hollow fiber membrane was used for the purification of the extract in different filtration modes, namely concentration and diafiltration, and a combination of both modes. Permeate fluxes and rejection rates were evaluated at different transmembrane pressure (TMP) at the shear rate of 10,187 s–1, at 40 °C. In concentration mode, increasing the volume reduction factor up to 6.1 led to a significant increase in the retention rates of acid-soluble lignin (ASL) and xylan, and a decrease in inorganic salt content in the retentate. In diafiltration mode, after 2.9 diavolumes, the acid-insoluble lignin (AIL) and xylan rejection rates drastically increased, as did the rejection rates of ash.
      Citation: Clean Technologies
      PubDate: 2023-04-23
      DOI: 10.3390/cleantechnol5020027
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 531-568: Investigation of Hydrogen
           Production System-Based PEM EL: PEM EL Modeling, DC/DC Power Converter,
           and Controller Design Approaches

    • Authors: Mohamed Koundi, Hassan El Fadil, Zakaria EL Idrissi, Abdellah Lassioui, Abdessamad Intidam, Tasnime Bouanou, Soukaina Nady, Aziz Rachid
      First page: 531
      Abstract: The main component of the hydrogen production system is the electrolyzer (EL), which is used to convert electrical energy and water into hydrogen and oxygen. The power converter supplies the EL, and the controller is used to ensure the global stability and safety of the overall system. This review aims to investigate and analyze each one of these components: Proton Exchange Membrane Electrolyzer (PEM EL) electrical modeling, DC/DC power converters, and control approaches. To achieve this desired result, a review of the literature survey and an investigation of the PEM EL electrical modeling of the empirical and semi-empirical, including the static and dynamic models, are carried out. In addition, other sub-models used to predict the temperature, gas flow rates (H2 and O2), hydrogen pressure, and energy efficiency for PEM EL are covered. DC/DC power converters suitable for PEM EL are discussed in terms of efficiency, current ripple, voltage ratio, and their ability to operate in the case of power switch failure. This review involves analysis and investigation of PEM EL control strategies and approaches previously used to achieve control objectives, robustness, and reliability in studying the DC/DC converter-PEM electrolyzer system. The paper also highlights the online parameter identification of the PEM electrolyzer model and adaptive control issues. Finally, a discussion of the results is developed to emphasize the strengths, weaknesses, and imperfections of the literature on this subject as well as proposing ideas and challenges for future work.
      Citation: Clean Technologies
      PubDate: 2023-04-23
      DOI: 10.3390/cleantechnol5020028
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 569-583: Use of Propyl Gallate in Cardoon
           Biodiesel to Keep Its Main Properties during Oxidation

    • Authors: Sergio Nogales-Delgado, Agustina Guiberteau Guiberteau Cabanillas, Juan Pedro Moro, José María Encinar Encinar Martín
      First page: 569
      Abstract: The use of alternatives for petroleum-based products is becoming more and more important, especially considering the new and constantly changing geopolitical context, where excessive energy dependence is not desirable. Thus, biodiesel could play an important role in contributing to the implementation of biorefineries, which represent desirable goals in terms of sustainability, green chemistry and the circular economy. However, one challenge related to biodiesel based on vegetable oils is its low oxidative stability, which can alter the properties of these products during storage. To avoid this problem, interesting antioxidants, such as propyl gallate (PG), could be added to biodiesel to allow it to keep its main properties during oxidation. Additionally, monitoring PG content during oxidation is interesting, and the use of voltammetry could be suitable for this purpose. The aim of this work was to assess the effectiveness of PG during cardoon biodiesel oxidation, while monitoring the process through cyclic voltammetry (CV). As a result, it was proven that PG was highly effective, increasing the length of oxidative stability to more than 10 h at low concentrations (600 mg·L−1) and retaining its main properties (viscosity and acidity) during oxidation. Regarding CV, this technique was successfully optimized to determine PG concentration in cardoon biodiesel during oxidation.
      Citation: Clean Technologies
      PubDate: 2023-05-02
      DOI: 10.3390/cleantechnol5020029
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 584-608: Vapor Compression Cycle: A
           State-of-the-Art Review on Cycle Improvements, Water and Other Natural

    • Authors: Fadi Alsouda, Nick S. Bennett, Suvash C. Saha, Fatemeh Salehi, Mohammad S. Islam
      First page: 584
      Abstract: Air conditioning and refrigeration have become necessary in modern life, accounting for more than 7.8% of greenhouse gases (GHG) emitted globally. Reducing the environmental impact of these systems is crucial for meeting the global GHG emission targets. Two principal directions must be considered to reduce the environmental impact of air conditioning systems. Firstly, reducing the direct effect by looking at less harmful refrigerants and secondly, reducing the indirect effect by searching for options to improve the system efficiency. This study presents the latest developments in the vapor compression cycle and natural refrigerants, focusing on water as a refrigerant. Natural refrigerants, and especially water, could be the ultimate solution for the environmental problems associated with the operation of vapor compression cycle (VCC) cooling systems, including ozone depletion (OD) and global warming (GW). Reducing the environmental impact of building cooling systems is essential, and the recent system improvements made to enhance the system coefficient of performance (COP) are thoroughly discussed in this paper. Though the cycle improvements discussed in this work are essential and could increase the system efficiency, they still need to solve the direct environmental impact of refrigerants. Accordingly, this paper suggests that natural refrigerants, including water, are the most suitable strategic choice to replace the current refrigerants in the refrigeration and air conditioning industry. Finally, this study reviews the latest VCC system improvements and natural refrigerants in order to guide interested researchers with solutions that may reduce the environmental impact of VCC systems and suggest future research areas.
      Citation: Clean Technologies
      PubDate: 2023-05-05
      DOI: 10.3390/cleantechnol5020030
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 609-637: Carbon Capture, Utilization, and
           Storage in Saline Aquifers: Subsurface Policies, Development Plans, Well
           Control Strategies and Optimization Approaches—A Review

    • Authors: Ismail Ismail, Vassilis Gaganis
      First page: 609
      Abstract: To mitigate dangerous climate change effects, the 195 countries that signed the 2015 Paris Agreement agreed to “keep the increase in average global surface temperature below 2 °C and limit the increase to 1.5 °C” by reducing carbon emissions. One promising option for reducing carbon emissions is the deployment of carbon capture, utilization, and storage technologies (CCUS) to achieve climate goals. However, for large-scale deployment of underground carbon storage, it is essential to develop technically sound, safe, and cost-effective CO2 injection and well control strategies. This involves sophisticated balancing of various factors such as subsurface engineering policies, technical constraints, and economic trade-offs. Optimization techniques are the best tools to manage this complexity and ensure that CCUS projects are economically viable while maintaining safety and environmental standards. This work reviews thoroughly and critically carbon storage studies, along with the optimization of CO2 injection and well control strategies in saline aquifers. The result of this review provides the foundation for carbon storage by outlining the key subsurface policies and the application of these policies in carbon storage development plans. It also focusses on examining applied optimization techniques to develop CO2 injection and well control strategies in saline aquifers, providing insights for future work and commercial CCUS applications.
      Citation: Clean Technologies
      PubDate: 2023-05-15
      DOI: 10.3390/cleantechnol5020031
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 638-651: Cyanobacteria Arthospira platensis
           as an Effective Tool for Gadolinium Removal from Wastewater

    • Authors: Nikita Yushin, Inga Zinicovscaia, Liliana Cepoi, Tatiana Chiriac, Ludmila Rudi, Dmitrii Grozdov
      First page: 638
      Abstract: The biosorption and bioaccumulation of gadolinium by Arthospira platensis in batch experiments was examined. In biosorption experiments, the influence of pH, gadolinium concentration, time of contact and temperature on Arthospira platensis sorption capacity was investigated. The maximum biosorption capacity of 101 mg/g was attained at a pH of 3.0 and temperature of 20 °C. A pseudo-first-order model was applicable to describe the kinetics of the biosorption and the Freundlich model to explain the equilibrium of the process. In bioaccumulation experiments, besides the examination of the gadolinium uptake by Arthospira platensis, its effect on biomass productivity as well as the content of proteins, lipids, carbohydrates and pigments was assessed. The addition of gadolinium in the cultivation medium resulted in the increase in biomass productivity and the content of MDA and, at the same time, in the reduction in the amount of proteins and carbohydrates. The content of other monitored parameters did not change significantly. The water extracts obtained from Arthospira platensis showed a higher antiradical activity against the ABTS cation radical in comparison with ethanolic extracts. Arthospira platensis is of interest for the development of the technology of gadolinium-contaminated wastewater remediation.
      Citation: Clean Technologies
      PubDate: 2023-05-17
      DOI: 10.3390/cleantechnol5020032
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 652-674: Material Flow Cost Accounting as a
           Resource-Saving Tool for Emerging Recycling Technologies

    • Authors: Caitlin Walls, Almy Ruzni Keumala Putri, Gesa Beck
      First page: 652
      Abstract: Material Flow Cost Accounting (MFCA) is an environmental management accounting method that allocates costs to material and energy flows through a process, thereby enabling a simultaneous reduction in environmental impacts alongside an improvement in business and economic efficiency. This study illustrates the versatility of MFCA beyond its usual application to existing production and manufacturing processes. In this paper, MFCA is used to assess the financial viability of two emerging recycling technologies, IRETA2 (Development and Evaluation of Recycling Routes to Recover Tantalum from Electronic Waste) and ReComp (Development of an Innovative, Economically and Ecologically Sensible Recycling Method for Metallised ABS and PC/ABS Composite Waste). These two projects differ in their process structure. Whilst IRETA2 is a strictly linear recycling process, ReComp consists of two process streams, split according to the treatment of its two material fractions. For both projects, the lab-scale experimental results were used to develop an MFCA model of the recycling process scaled at each project partner’s facilities. MFCA was utilised to calculate the projects’ overall profit or loss, the impact of the final products’ market conditions and processing rate (in the case of IRETA2), or machinery capacity (for ReComp) on the overall results. The results show that neither IRETA2 nor ReComp are financially viable based on the current output products’ market value and quantity produced. However, through a sensitivity analysis, it is demonstrated that IRETA2 could become financially viable if the processing rate or market conditions were to improve. Additionally, ReComp could become financially viable if there was an increase in machine capacity. Finally, this paper also explores possible implications of MFCA when applied to emerging recycling technologies on EU policy and strategy, particularly those related to the EU Green Deal, such as extended producer responsibility and supply chain acts.
      Citation: Clean Technologies
      PubDate: 2023-05-17
      DOI: 10.3390/cleantechnol5020033
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 675-695: Torrefaction of Pine Using a
           Pilot-Scale Rotary Reactor: Experimentation, Kinetics, and Process
           Simulation Using Aspen Plus™

    • Authors: Suchandra Hazra, Prithvi Morampudi, John C. Prindle, Dhan Lord B. Fortela, Rafael Hernandez, Mark E. Zappi, Prashanth Buchireddy
      First page: 675
      Abstract: Biomass is an excellent sustainable carbon neutral energy source, however its use as a coal/petroleum coke substitute in thermal applications poses several challenges. Several inherent properties of biomass including higher heating value (HHV), bulk density, and its hydrophilic and fibrous nature, all contribute to challenges for it to be used as a solid fuel. Torrefaction or mild pyrolysis is a well-accepted thermal pretreatment technology that solves most of the above-mentioned challenges and results in a product with superior coal-like properties. Torrefaction involves the heating of biomass to moderate temperatures typically between 200 °C and 300 °C in a non-oxidizing atmosphere. This study focused on evaluating the influence of torrefaction operating temperature (204–304 °C) and residence time (10–40 min) on properties of pine. Tests were performed on a continuous 0.3 ton/day indirectly heated rotary reactor. The influence of torrefaction operational conditions on pine was evaluated in terms of the composition of torrefied solids, mass yield, energy yield, and HHV using a simulated model developed in Aspen Plus™ software. A kinetic model was established based on the experimental data generated. An increase in torrefaction severity (increasing temperature and residence time) resulted in an increase in carbon content, accompanied with a decrease in oxygen and hydrogen. Results from the simulated model suggest that the solid and energy yields decreased with an increase in temperature and residence time. Solid yield varied from 80% at 204 °C to 68% at 304 °C, and energy yield varied from 99% at 204 °C to 70% at 304 °C, respectively. On the other hand, HHV improved from 22.8 to 25.1 MJ/kg with an increase in temperature at 20 min residence time. Over the range of 10 to 40 min residence time at 260 °C, solid and energy yields varied from 77% to 59% and 79% to 63%, respectively; however the HHV increased by only 3%. Solid yield, energy yield, and HHV simulated data were within the 5% error margin when compared to the experimental data. Validation of the simulation parameters was achieved by the conformance of the experimental and simulation data obtained under the same testing conditions. These simulated parameters can be utilized to study other operating conditions fundamental for the commercialization of these processes. Desirable torrefaction temperature to achieve the highest solid fuel yield can be determined using the energy yield and mass loss data.
      Citation: Clean Technologies
      PubDate: 2023-05-17
      DOI: 10.3390/cleantechnol5020034
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 696-712: CO2 Emissions of Battery Electric
           Vehicles and Hydrogen Fuel Cell Vehicles

    • Authors: Lucian-Ioan Dulău
      First page: 696
      Abstract: During the last few years, electric and hydrogen vehicles have become an alternative to cars that use internal combustion engines. The number of electric and hydrogen vehicles sold has increased due to support from local governments and because car manufacturers will stop the production of internal combustion engines in the near future. The emissions of these vehicles while being driven are zero, but they still have an impact on the environment due to their fuel. In this article, an analysis of carbon dioxide (CO2) emissions for two types of vehicles: battery electric vehicles (BEVs) powered by electricity and fuel cell electric vehicles (FCEVs) powered by hydrogen, is presented. The analysis considers different values for the mix of power generation and hydrogen production options in comparison to other studies. The CO2 emissions were calculated and compared for the two types of vehicles. The results show that the CO2 emissions of BEVs are lower when compared to FCEVs if the hydrogen is obtained from pollutant sources and is higher if the hydrogen is obtained from nuclear power and renewable energy sources. When compared to conventional combustion engine vehicles, BEVs have lower CO2 emissions, while the emissions of FCEVs are dependent on the hydrogen production method.
      Citation: Clean Technologies
      PubDate: 2023-06-01
      DOI: 10.3390/cleantechnol5020035
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 713-743: Alternative Fuel Substitution
           Improvements in Low NOx In-Line Calciners

    • Authors: Essossinam Beguedou, Satyanarayana Narra, Komi Agboka, Damgou Mani Kongnine, Ekua Afrakoma Armoo
      First page: 713
      Abstract: The process of making cement clinker uses a lot of energy and produces a lot of pollution. Currently, cement companies use a combination of traditional fossil fuels and alternative fuels (AF-Fuels) to lower their energy consumption and environmental footprint by improving the pyro-system. In a calciner, AF-Fuels can reach a thermal substitution rate (TSR) of up to 80–100%. However, a kiln burner can only achieve a TSR of 50–60%. High TSR values have been provided by improvements in multi-channel burners, proper AF-Fuel feeding point setups, and various AF pre-combustion methods. Significant modeling of the calciner burner and system has also improved TSRs. However, the cement industry has encountered operational problems such as kiln coating build-up, reduced flame temperatures, higher specific heat consumption, and incomplete combustion. There is growing interest in waste substitution, a promising source of AF-Fuel that needs to be integrated into the current cement plant design to solve the calciner operational problems of the cement industry. This study discusses the latest developments and different experimental and modeling studies performed on the direct burning/co-firing of AF-Fuel in the cement industry as well as the incorporation of gasification in cement manufacturing. Based on this, a technically and environmentally improved solution is proposed. The characteristics of both approaches towards pre-calciner function and optimization are critically assessed. The many in-line cement calciner integration technologies and their various configurations for the long-term problems of cement plants are discussed. This project report also focuses on the necessity of creating appropriate calciner models for forecasting calciner production based on various AF-Fuels and their feeding positions in the calciner.
      Citation: Clean Technologies
      PubDate: 2023-06-01
      DOI: 10.3390/cleantechnol5020036
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 744-765: Forecast Optimization of Wind Speed
           in the North Coast of the Yucatan Peninsula, Using the Single and Double
           Exponential Method

    • Authors: Christy Pérez-Albornoz, Ángel Hernández-Gómez, Victor Ramirez, Damien Guilbert
      First page: 744
      Abstract: Installation of new wind farms in areas such as the north coast of the Yucatan peninsula is of vital importance to face the local energy demand. For the proper functioning of these facilities it is important to perform wind data analysis, the data having been collected by anemometers, and to consider the particular characteristics of the studied area. However, despite the great development of anemometers, forecasting methods are necessary for the optimal harvesting of wind energy. For this reason, this study focuses on developing an enhanced wind forecasting method that can be applied to wind data from the north coast of the Yucatan peninsula (in general, any type of data). Thus, strategies can be established to generate a greater amount of energy from the wind farms, which supports the local economy of this area. Four variants have been developed based on the traditional double and single exponential methods. Furthermore, these methods were compared to the experimental data to obtain the optimal forecasting method for the Yucatan area. The forecasting method with the highest performance has obtained an average relative error of 7.9510% and an average mean error of 0.3860 m/s.
      Citation: Clean Technologies
      PubDate: 2023-06-02
      DOI: 10.3390/cleantechnol5020037
      Issue No: Vol. 5, No. 2 (2023)
  • Clean Technol., Vol. 5, Pages 766-790: Moving towards Greener Road
           Transportation: A Review

    • Authors: Nick Rigogiannis, Ioannis Bogatsis, Christos Pechlivanis, Anastasios Kyritsis, Nick Papanikolaou
      First page: 766
      Abstract: Road transportation accounts for about 20% of the total GHG emissions in the EU. Nowadays, the substitution of conventional fossil fuel-based ICEs with electric engines, or their hybridization, operating along with Energy Storage Systems, seems to be the most appropriate measure to achieve reductions in both fuel consumption and GHGs. However, EVs encounter crucial challenges, such as long charging time and limited driving range. Hence, the transition to the mass adoption of EVs requires considerable effort and time. However, significant steps have been taken in the hybridization of road vehicles, with the aid of renewables and energy recovery/saving systems. In this context, this paper presents a comprehensive literature review of modern green technologies for GHG reduction that are applicable to road transportation, such as on-vehicle energy harvesting and recovery (e.g., thermal, kinetic, etc.) systems and the incorporation of RES into EV charging stations. The impact of road vehicles on the environment is discussed in detail, along with the EU roadmap towards the decarbonization of transportation. Next, methods and techniques for fuel consumption and GHG reduction are systematically presented and categorized into on-vehicle and off-vehicle ones. Finally, a future outlook on more environmentally friendly road transportation is presented.
      Citation: Clean Technologies
      PubDate: 2023-06-07
      DOI: 10.3390/cleantechnol5020038
      Issue No: Vol. 5, No. 2 (2023)
  • 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

    • 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 167-189: A Literature Review on Existing
           Methods and Indicators for Evaluating the Efficiency of Power-to-X

    • Authors: Natascha Eggers, Torsten Birth, Bernd Sankol, Lukas Kerpen, Antonio Hurtado
      First page: 167
      Abstract: The challenges posed by climate change have prompted significant growth in efficiency evaluation and optimization research, especially in recent years. This has spawned a variety of heterogeneous methods and approaches to the assessment of technical processes. These methods and approaches are rarely comparable and are usually only applicable to specific sectors. This paper provides an overview of the literature on efficiency assessment methods and KPIs, leading to a more manageable selection of an appropriate method with special regard to energy system integration technologies. In addition to reviewing the literature systematically, this paper examines existing methods and indicators’ applicability to and significance for efficiency optimization. In this context, a holistic approach to process design, evaluation, and improvement is given with particular regard to power-to-X systems. Within the framework of the study, three overarching goals could be defined as levels of efficiency evaluation of power-to-X systems: 1. identification of the process (steps) with the most significant optimization potential, 2. identification of the process phases with the greatest optimization potential (timewise considered), and 3. derivation of specific recommendations for action for the improvement of a process. For each of these levels, the most suitable evaluation methods were identified. While various methods, such as life cycle assessment and physical optimum, are particularly suitable for Level 1 and Level 2, for Level 3, even the best-identified methods have to be extended on a case-by-case basis. To address this challenge, a new approach to a holistic evaluation of power-to-X systems was developed based on the study’s findings.
      Citation: Clean Technologies
      PubDate: 2023-01-31
      DOI: 10.3390/cleantechnol5010010
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 190-202: Influence of the Presence of Poly
           (Butylene Succinate) in the Poly (Ethylene Terephthalate) Recycling

    • Authors: Cristina Pavon, Miguel Aldas, David Bertomeu, Harrison de la Rosa-Ramírez, María Dolores Samper, Juan López-Martínez
      First page: 190
      Abstract: Poly(butylene succinate) (PBS) is one of the contaminants in the poly (ethylene terephthalate) (PET) recycling process. It is known that high contents of PBS in PET significantly reduce PET properties, but the effect of low contents on PET has yet to be studied. This work studied the influence of low contents of PBS on recycled PET. Five formulations of PBS in PET were prepared, and the properties of relative affinity, mechanical, thermal, and disintegration under composting conditions were assessed. The solubility parameter indicated that PET and PBS are miscible. However, FESEM images show slight marks of immiscibility, and the mechanical characterization results showed that PBS, even in low contents, reduced the mechanical properties of recycled PET, which proves that the materials are not miscible in the studied contents. The DSC results indicated that PBS could not be quickly detected in PET. However, its presence can be inferred by the reduction in PET crystallization degree. Finally, the presence of PBS up to 15 wt.% does neither affect the disintegration under composting conditions nor the thermal stability of recycled PET. The drop in mechanical properties shows that PBS must be removed from the PET waste stream to preserve the quality of the material.
      Citation: Clean Technologies
      PubDate: 2023-01-31
      DOI: 10.3390/cleantechnol5010011
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 203-214: Electrochemical Treatment of
           Arsenic in Drinking Water: Effect of Initial As3+ Concentration, pH, and
           Conductivity on the Kinetics of Oxidation

    • Authors: Sabrina Sorlini, Marco Carnevale Miino, Zdravka Lazarova, Maria Cristina Collivignarelli
      First page: 203
      Abstract: Many technologies for the treatment of arsenic-containing drinking water are available, but most of them are more effective on arsenic oxidized forms. Therefore, the pre-oxidation of As3+ is necessary. The electrochemical processes represent a very promising method due to the simultaneous oxidation of compounds using electrochemical conditions and the reactive radicals produced. In this work, As3+ oxidation was experimentally studied at a pilot scale using an electrochemical oxidation cell (voltage: 10 V; current: 1.7 A). The effect of the initial arsenite concentration, pH, and conductivity of drinking water on the oxidation of As3+ into As5+ was investigated. The results showed that the initial As3+ concentration strongly directly influences the oxidation process. Increasing the initial arsenite concentration from 500 to 5000 µg L−1, the pseudo-first order kinetic constant (k) strongly decreased from 0.521 to 0.038 min−1, and after 10 min, only 21.3% of As3+ was oxidized (vs. 99.9% in the case of As3+ equal to 500 µg L−1). Slightly alkaline conditions (pH = 8) favored the electrochemical oxidation into As5+, while the process was partially inhibited in the presence of a more alkaline or acidic pH. The increase in conductivity up to 2000 µS cm−1 enhanced the kinetic of the oxidation, despite remaining on the same order of magnitude as in the case of conductivity equal to 700 µS cm−1. After 10 min, 99.9 and 95% of As3+ was oxidized, respectively. It is the opinion of the authors that the influence of other operational factors, such as voltage and current density, and the impact of the high concentration of other pollutants should be deeply studied in order to optimize the process, especially in the case of an application at full scale. However, these results provide helpful indications to future research having highlighted the influence of initial As3+ concentration, pH, and conductivity on the electrochemical oxidation of arsenic.
      Citation: Clean Technologies
      PubDate: 2023-02-03
      DOI: 10.3390/cleantechnol5010012
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 215-232: Techno-Economic Efficiency
           Estimation of Promising Integrated Oxyfuel Gasification Combined-Cycle
           Power Plants with Carbon Capture

    • Authors: Igor Donskoy
      First page: 215
      Abstract: The study concerns promising coal-fired power plants that can gain an advantage over traditional options in the context of decarbonization. The calculations show that combined-cycle plants with integrated coal gasification and carbon dioxide recirculation may have better technical and economic characteristics compared to existing gasification processes (one- and two-stage). The recirculation of carbon dioxide improves the efficiency of the gasification process (the combustible gases yield and the fuel carbon conversion degree) and reduces the energy costs of the flue gas cleaning and carbon capture unit, thereby improving the economic performance of the plant. The estimates show that the decrease in the efficiency of electricity production associated with the removal of carbon dioxide is approximately 8% for the recirculation of combustion products and 15–16% for traditional processes, and the increase in the cost of electricity is 20–25% versus 35–40%, respectively.
      Citation: Clean Technologies
      PubDate: 2023-02-06
      DOI: 10.3390/cleantechnol5010013
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 233-258: Energetic Valorization of Bio-Waste
           from Municipal Solid Waste in Porto Santo Island

    • Authors: Fabíola Pereira, Carlos Silva
      First page: 233
      Abstract: The valorization of bio-waste as a resource for green energy production will be beneficial at a social, economic, and environmental level in different regions. The scope of this research is to develop the energetic valorization of the bio-waste fraction from municipal solid waste, to produce biogas from the anaerobic digestion process and electricity in a biogas CHP process, to increase the penetration of renewables in the electricity production system, with an application of these technologies on islands instead of these waste fractions being transported to other regions. The methodologies developed included: 1. Identification and mapping of resources; 2. State-of-the-art of bio-waste parameters and process solutions; 3. Pilot initiative for separation, collection, and analysis of food waste fractions; 4. Development of process solutions according to resources and needs; 5. Determination of investment, production costs, and revenues of the solution created. The case study selected was Porto Santo Island, with the potential to reduce maritime transportation costs of these undifferentiated waste fractions to Madeira Island and contribute to developing an innovative solution for the energetic valorization of bio-waste, including the participation of the local community. The results demonstrated a production of 272,221 m3 of biogas for use as fuel in a cogeneration unit to transform chemical energy into electrical and thermal energies. Furthermore, the self-consumption of the cogeneration unit is 25% of the total electricity produced and 29% of the total thermal energy produced. In conclusion, this research and solution is in compliance with PNEC, the EU Green Deal, and the European Directive 2018/851, which will make mandatory from 2024: the selective collection of bio-waste, 60% by weight of urban waste to be recycled by 2030, and only 10% of waste to be landfilled by 2035.
      Citation: Clean Technologies
      PubDate: 2023-02-08
      DOI: 10.3390/cleantechnol5010014
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 259-273: Rheological Behavior and
           Characterization of Drinking Water Treatment Sludge from Morocco

    • Authors: Fantasse Azeddine, Parra Angarita Sergio, Léonard Angélique, Lakhal El Khadir, Idlimam Ali, Bougayr El Houssayne
      First page: 259
      Abstract: Drinking water treatment generates a high amount of pasty by-product known as drinking water treatment sludge (DWTS). The chemical composition, microstructure and rheological behavior of DWTS are of utmost importance in the calculation, design, optimization, commissioning and control of its treatment processes. The purpose of this research was to characterize the DWTS from the drinking water treatment plant of Marrakech (Morocco), aiming to help future researchers and engineers in predicting its hydrodynamic behavior. The first part of this study was devoted to the physical structure and the chemical composition of sludge. The second part was oriented towards the study of the mechanical properties; a penetration test and a rotational rheology test were performed. For the first test, a force–length penetration diagram was plotted in order to calculate the hardness, the cohesiveness and the adhesiveness of DWTS. For the second test, the shear stress and the apparent viscosity were plotted and fitted to five rheological models, as function of the shear rate, aiming to describe the rheological behavior of samples. The obtained results reveal that the drinking water treatment sludge from Marrakech is a porous, amorphous and highly adhesive material, with a shear-thinning (pseudoplastic) rheological behavior that can be described according to the Herschel–Bulkley model (better in low-rate stresses, R² = 0.98) or the Windhad model (better in high shear rates, R² = 0.96) and is mainly composed of silica, aluminum and iron oxides.
      Citation: Clean Technologies
      PubDate: 2023-02-16
      DOI: 10.3390/cleantechnol5010015
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 274-296: Membranes and Integrated Membrane
           Operations as Clean Technologies in the Leather Industry

    • Authors: Enrico Drioli, Alfredo Cassano
      First page: 274
      Abstract: The leather industry is characterized by the production of a huge amount of wastewater with a high organic/inorganic charge, causing widespread water and soil pollution. Pressure-driven membrane operations and membrane bioreactors have long been proven to be a valid approach for the treatment of tanning wastewaters aimed at the recovery of raw materials as well as for the removal of toxic and environmentally harmful substances. Such processes, opportunely integrated among themselves and/or with conventional physical-chemical and biological treatments, also provide useful protocols for the treatment of global wastewaters with significant advantages in terms of environmental protection, decrease of disposal costs, simplification of cleaning-up processes and saving of water and chemicals. This paper, as the state of the art, attempts to revise the potential and perspectives of membrane-based technologies in the leather industry with related applications in beamhouse, tanning and post-tanning operations as well as in the treatment of global wastewaters.
      Citation: Clean Technologies
      PubDate: 2023-02-16
      DOI: 10.3390/cleantechnol5010016
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 297-328: Design-Based Approach to Support
           Sorting Behavior of Food Packaging

    • Authors: Babak Nemat, Mohammad Razzaghi, Kim Bolton, Kamran Rousta
      First page: 297
      Abstract: It is widely acknowledged that environmental impacts from packaging waste depend on how consumers sort this waste fraction. In this research, “design for sustainable behavior” (DfSB) strategies are used to improve a cream packaging design that can support proper sorting of packaging waste as a sustainable behavior. The application of three DfSB strategies—“match”, “steer”, and “force”—was examined through circular interviews and practical experience with two groups of participants in Karlskrona, Sweden. Prototyping was used to provide a more realistic experiment and enhance communication during the interviews. The results show that consumer-packaging interaction during the usage phase is important to enhance proper sorting behavior. The results also show the potential of a user-centered design-based approach to study consumer-packaging interaction and to understand the challenges faced by users when sorting packaging waste. It also shows the possibility of packaging design to script consumer behavior and reveals details that are important when designing packaging that was not known. In this vein, packaging form, color, and haptic attributes are the most influential design attributes that can support packaging functionalities and script consumer sorting behavior.
      Citation: Clean Technologies
      PubDate: 2023-02-28
      DOI: 10.3390/cleantechnol5010017
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 329-351: Model-Based Predictive Control of a
           Solar Hybrid Thermochemical Reactor for High-Temperature Steam
           Gasification of Biomass

    • Authors: Youssef Karout, Axel Curcio, Julien Eynard, Stéphane Thil, Sylvain Rodat, Stéphane Abanades, Valéry Vuillerme, Stéphane Grieu
      First page: 329
      Abstract: The present paper deals with both the modeling and the dynamic control of a solar hybrid thermochemical reactor designed to produce syngas through the high-temperature steam gasification of biomass. First, a model of the reactor based on the thermodynamic equilibrium is presented. The Cantera toolbox is used. Then, a model-based predictive controller (MPC) is proposed with the aim of maintaining the reactor’s temperature at its nominal value, thus preserving the reactor’s stability. This is completed by adjusting the mirrors’ defocusing factor or burning a part of the biomass to compensate for variations of direct normal irradiance (DNI) round the clock. This controller is compared to a reference controller, which is defined as a combination of a rule-based controller and an adaptive proportional–integral–derivative (PID) controller with optimized gains. The robustness of the MPC controller to forecast errors is also studied by testing different DNI forecasts: perfect forecasts, smart persistence forecasts and image-based forecasts. Because of a high optimization time, the Cantera function is replaced with a 2D interpolation function. The results show that (1) the developed MPC controller outperforms the reference controller, (2) the integration of image-based DNI forecasts produces lower root mean squared error (RMSE) values, and (3) the optimization time is significantly reduced thanks to the proposed interpolation function.
      Citation: Clean Technologies
      PubDate: 2023-03-02
      DOI: 10.3390/cleantechnol5010018
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 352-402: Arsenic Removal by Adsorbents from
           Water for Small Communities’ Decentralized Systems: Performance,
           Characterization, and Effective Parameters

    • Authors: Roya Sadat Neisan, Noori M. Cata Saady, Carlos Bazan, Sohrab Zendehboudi, Abbas Al-nayili, Bassim Abbassi, Pritha Chatterjee
      First page: 352
      Abstract: Arsenic (As), a poisonous and carcinogenic heavy metal, affects human health and the environment. Numerous technologies can remove As from drinking water. Adsorption is the most appealing option for decentralized water treatment systems (DWTS) for small communities and household applications because it is reliable, affordable, and environmentally acceptable. Sustainable low-cost adsorbents make adsorption more appealing for DWTS to address some of the small communities’ water-related issues. This review contains in-depth information on the classification and toxicity of As species and different treatment options, including ion exchange, membrane technologies, coagulation-flocculation, oxidation, and adsorption, and their effectiveness under various process parameters. Specifically, different kinetic and isotherm models were compared for As adsorption. The characterization techniques that determine various adsorbents’ chemical and physical characteristics were investigated. This review discusses the parameters that impact adsorption, such as solution pH, temperature, initial As concentration, adsorbent dosage, and contact time. Finally, low-cost adsorbents application for the removal of As was discussed. Adsorption was found to be a suitable, cost-effective, and reliable technology for DWTS for small and isolated communities. New locally developed and low-cost adsorbents are promising and could support sustainable adsorption applications.
      Citation: Clean Technologies
      PubDate: 2023-03-06
      DOI: 10.3390/cleantechnol5010019
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 403-417: Graphene Embedded with Transition

    • Authors: Fatemeh Mollaamin, Majid Monajjemi
      First page: 403
      Abstract: Carbon dioxide (CO2) adsorption on decorated graphene (GR) sheets with transition metals (TMs) including iron, nickel and zinc was investigated for removing this hazardous gas from the environment. TM-doped GR results in higher activity toward gas detecting than pristine graphene nanosheets. TM embedding restrains hydrogen evolution on the C sites, leaving more available sites for a CO2 decrease. The Langmuir adsorption model with ONIOM using CAM-B3LYP functional and LANL2DZ and 6-31+G (d,p) basis sets due to Gaussian 16 revision C.01 program on the complexes of CO2→(Fe, Ni, Zn) embedded on the GR was accomplished. The changes of charge density illustrated a more considerable charge transfer for Zn-embedded GR. The thermodynamic results from IR spectroscopy indicated that ΔGads,CO2→Zn@C−GRo has the notable gap of Gibbs free energy adsorption with a dipole moment which defines the alterations between the Gibbs free energy of the initial compounds (ΔGCO2 o and ΔGZn@C−GRo) and product compound (ΔGCO2→Zn@C−GRo) through polarizability. Frontier molecular orbital and band energy gaps accompanying some chemical reactivity parameters represented the behavior of molecular electrical transport of the (Fe, Ni, Zn) embedding of GR for the adsorption of CO2 gas molecules. Our results have provided a favorable understanding of the interaction between TM-embedded graphene nanosheets and CO2.
      Citation: Clean Technologies
      PubDate: 2023-03-09
      DOI: 10.3390/cleantechnol5010020
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 418-435: Unsupervised Machine Learning to
           Detect Impending Anomalies in Testing of Fuel Economy and Emissions of
           Light-Duty Vehicles

    • Authors: Dhan Lord B. Fortela, Ashton C. Fremin, Wayne Sharp, Ashley P. Mikolajczyk, Emmanuel Revellame, William Holmes, Rafael Hernandez, Mark Zappi
      First page: 418
      Abstract: This work focused on demonstrating the capability of unsupervised machine learning techniques in detecting impending anomalies by extracting hidden trends in the datasets of fuel economy and emissions of light-duty vehicles (LDVs), which consist of cars and light-duty trucks. This case study used the vehicles’ fuel economy and emissions testing datasets for vehicle model years 2015 to 2023 with a total of 34,602 data samples on LDVs of major vehicle manufacturers. Three unsupervised techniques were used: principal components analysis (PCA), K-Means clustering, and self-organizing maps (SOM). Results show that there are clusters of data that exhibit trends not represented by the dataset as a whole. Fuel CO vs. Fuel Economy has a negative correlation in the whole dataset (r = −0.355 for LDVs model year 2022), but it has positive correlations in certain sample clusters (e.g., LDVs model year 2022: r = +0.62 in a K-Means cluster where the slope is around 0.347 g−CO/mi/MPG). A time series analysis of the results of clustering indicates that Test Procedure and Fuel Type, specifically Test Procedure 11 and Fuel Type 26 as defined by the US EPA, could be the contributors to the positive correlation of CO and Fuel Economy. This detected peculiar trend of CO-vs.-Fuel Economy is an impending anomaly, as the use of Fuel 26 in emissions testing with Test Procedure 11 of US-EPA has been increasing through the years. With the finding that the clustered data samples with positive CO-vs.-Fuel Economy correlation all came from vehicle manufacturers that independently conduct the standard testing procedures and not data from US-EPA testing centers, it was concluded that the chemistry of using Fuel 26 in performing Test Procedure 11 should be re-evaluated by US-EPA.
      Citation: Clean Technologies
      PubDate: 2023-03-13
      DOI: 10.3390/cleantechnol5010021
      Issue No: Vol. 5, No. 1 (2023)
  • Clean Technol., Vol. 5, Pages 436-450: Public Acceptance and Willingness
           to Pay for Carbon Capture and Utilisation Products

    • Authors: Tryfonas Pieri, Alexandros Nikitas, Athanasios Angelis-Dimakis
      First page: 436
      Abstract: Although the significance of the social science agenda reflecting and affecting the carbon capture and utilisation (CCU) value chain has been acknowledged, there is still a scarcity of research about it. This work contributes in developing an understanding of public perceptions regarding the acceptance, use, and purchasing of carbon dioxide (CO2)-derived products through an online quantitative survey. Our research suggests the awareness and acceptance of such products are relatively high. Respondents were in favour of CO2-derived product promotion by policy makers and the industry, approved the funding of such schemes by government, and supported companies that use captured CO2 in their products. The product category seems to influence the willingness of people to use and buy CO2-derived products, with our respondents being more willing to use CO2-derived fuels than food or beverages, showing a caution toward health-related risks. Respondents were also more willing to buy a CO2-derived product if it was cheaper or better for the environment. Male respondents were in general less willing to pay for CCU-based products, while people aged 25 to 29 were more positive toward them. We conclude that the public will be in favour of CCU-based products and willing to buy them if the involved stakeholders do their part in delivering a safe product at a comparable quality and price to existing ones. Better information provision can also support this cause.
      Citation: Clean Technologies
      PubDate: 2023-03-13
      DOI: 10.3390/cleantechnol5010022
      Issue No: Vol. 5, No. 1 (2023)
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