Subjects -> ENVIRONMENTAL STUDIES (Total: 960 journals)
    - ENVIRONMENTAL STUDIES (853 journals)
    - POLLUTION (31 journals)
    - WASTE MANAGEMENT (18 journals)

ENVIRONMENTAL STUDIES (853 journals)                  1 2 3 4 5 | Last

Showing 1 - 200 of 378 Journals sorted alphabetically
ACS Chemical Health & Safety     Hybrid Journal   (Followers: 5)
ACS ES&T Engineering     Hybrid Journal   (Followers: 9)
Acta Brasiliensis     Open Access   (Followers: 3)
Acta Ecologica Sinica     Open Access   (Followers: 11)
Acta Environmentalica Universitatis Comenianae     Open Access   (Followers: 1)
Acta Limnologica Brasiliensia     Open Access   (Followers: 4)
Acta Oecologica     Hybrid Journal   (Followers: 12)
Acta Regionalia et Environmentalica     Open Access   (Followers: 1)
Advanced Electronic Materials     Hybrid Journal   (Followers: 7)
Advanced Energy and Sustainability Research     Open Access   (Followers: 7)
Advanced Sustainable Systems     Hybrid Journal   (Followers: 7)
Advances in Ecological Research     Full-text available via subscription   (Followers: 45)
Advances in Environmental Chemistry     Open Access   (Followers: 11)
Advances in Environmental Sciences - International Journal of the Bioflux Society     Open Access   (Followers: 21)
Advances in Environmental Technology     Open Access   (Followers: 1)
Advances in Life Science and Technology     Open Access   (Followers: 23)
Advances in Tropical Biodiversity and Environmental Sciences     Open Access   (Followers: 5)
Aeolian Research     Hybrid Journal   (Followers: 6)
African Journal of Environmental Science and Technology     Open Access   (Followers: 5)
Agricultura Tecnica     Open Access   (Followers: 5)
Agricultural & Environmental Letters     Open Access   (Followers: 3)
Agro-Science     Full-text available via subscription   (Followers: 3)
Agroecological journal     Open Access  
Agronomy for Sustainable Development     Open Access   (Followers: 22)
Agrosystems, Geosciences & Environment     Open Access   (Followers: 7)
Amazon's Research and Environmental Law     Open Access   (Followers: 5)
Ambiência     Open Access  
Ambiens. Revista Iberoamericana Universitaria en Ambiente, Sociedad y Sustentabilidad     Open Access   (Followers: 1)
Ambiente & sociedade     Open Access   (Followers: 3)
Ambiente & Agua : An Interdisciplinary Journal of Applied Science     Open Access   (Followers: 1)
American Journal of Energy and Environment     Open Access   (Followers: 5)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Environmental Protection     Open Access   (Followers: 9)
American Journal of Environmental Sciences     Open Access   (Followers: 11)
American Naturalist     Full-text available via subscription   (Followers: 85)
Annals of Civil and Environmental Engineering     Open Access   (Followers: 3)
Annals of Environmental Science and Toxicology     Open Access   (Followers: 3)
Annals of GIS     Open Access   (Followers: 29)
Annual Review of Ecology, Evolution, and Systematics     Full-text available via subscription   (Followers: 89)
Annual Review of Environment and Resources     Full-text available via subscription   (Followers: 16)
Annual Review of Pharmacology and Toxicology     Full-text available via subscription   (Followers: 36)
Annual Review of Resource Economics     Full-text available via subscription   (Followers: 10)
Applied and Environmental Soil Science     Open Access   (Followers: 20)
Applied Ecology and Environmental Sciences     Open Access   (Followers: 30)
Applied Environmental Education & Communication     Hybrid Journal   (Followers: 19)
Applied Journal of Environmental Engineering Science     Open Access   (Followers: 2)
Aquatic Ecology     Hybrid Journal   (Followers: 39)
Aquatic Toxicology     Hybrid Journal   (Followers: 25)
Arcada : Revista de conservación del patrimonio cultural     Open Access   (Followers: 2)
Architecture, Civil Engineering, Environment     Open Access   (Followers: 4)
Archives des Maladies Professionnelles et de l'Environnement     Full-text available via subscription  
Archives of Environmental and Occupational Health     Hybrid Journal   (Followers: 12)
Archives of Environmental Contamination and Toxicology     Hybrid Journal   (Followers: 14)
Archives of Toxicology     Hybrid Journal   (Followers: 20)
Arctic Environmental Research     Open Access   (Followers: 1)
Asian Journal of Environment & Ecology     Open Access   (Followers: 1)
Asian Journal of Rural Development     Open Access   (Followers: 9)
Asian Review of Environmental and Earth Sciences     Open Access   (Followers: 3)
ATBU Journal of Environmental Technology     Open Access   (Followers: 5)
Atmospheric and Climate Sciences     Open Access   (Followers: 35)
Atmospheric Environment     Hybrid Journal   (Followers: 75)
Atmospheric Environment : X     Open Access   (Followers: 3)
Augm Domus : Revista electrónica del Comité de Medio Ambiente de AUGM     Open Access  
Austral Ecology     Hybrid Journal   (Followers: 18)
Australasian Journal of Environmental Management     Hybrid Journal   (Followers: 13)
Australasian Journal of Human Security     Full-text available via subscription   (Followers: 1)
Australian Journal of Environmental Education     Full-text available via subscription   (Followers: 11)
Basic & Clinical Pharmacology & Toxicology     Hybrid Journal   (Followers: 13)
Basic and Applied Ecology     Hybrid Journal   (Followers: 25)
Behavioral Ecology     Hybrid Journal   (Followers: 60)
Behavioral Ecology and Sociobiology     Hybrid Journal   (Followers: 38)
Biocenosis     Open Access  
Biochar     Hybrid Journal   (Followers: 3)
Biodegradation     Hybrid Journal   (Followers: 2)
Biodiversity     Hybrid Journal   (Followers: 30)
Biofouling: The Journal of Bioadhesion and Biofilm Research     Hybrid Journal   (Followers: 7)
Bioremediation Journal     Hybrid Journal   (Followers: 5)
BioRisk     Open Access   (Followers: 3)
BMC Ecology     Open Access   (Followers: 24)
Boletín Instituto de Derecho Ambiental y de los Recursos Naturales     Open Access  
Boletín Semillas Ambientales     Open Access  
Boston College Environmental Affairs Law Review     Open Access   (Followers: 7)
Bothalia : African Biodiversity & Conservation     Open Access   (Followers: 1)
Built Environment     Full-text available via subscription   (Followers: 5)
Bulletin of Environmental Contamination and Toxicology     Hybrid Journal   (Followers: 15)
Bulletin of the American Meteorological Society     Open Access   (Followers: 51)
Bumi Lestari Journal of Environment     Open Access  
Canadian Journal of Earth Sciences     Hybrid Journal   (Followers: 23)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 50)
Canadian Journal of Soil Science     Full-text available via subscription   (Followers: 14)
Canadian Water Resources Journal     Hybrid Journal   (Followers: 20)
Capitalism Nature Socialism     Hybrid Journal   (Followers: 27)
Carbon Resources Conversion     Open Access   (Followers: 3)
Case Studies in Chemical and Environmental Engineering     Open Access   (Followers: 1)
Casopis Slezskeho Zemskeho Muzea - serie A - vedy prirodni     Open Access  
Cell Biology and Toxicology     Hybrid Journal   (Followers: 12)
Chain Reaction     Full-text available via subscription  
Challenges in Sustainability     Open Access   (Followers: 12)
Chemical Research in Toxicology     Hybrid Journal   (Followers: 25)
Chemico-Biological Interactions     Hybrid Journal   (Followers: 3)
Chemosphere     Hybrid Journal   (Followers: 17)
Child and Adolescent Mental Health     Hybrid Journal   (Followers: 72)
China Population, Resources and Environment     Full-text available via subscription   (Followers: 4)
Ciencia, Ambiente y Clima     Open Access   (Followers: 3)
City and Environment Interactions     Open Access   (Followers: 4)
Civil and Environmental Engineering     Open Access   (Followers: 8)
Civil and Environmental Engineering Reports     Open Access   (Followers: 9)
Civil and Environmental Research     Open Access   (Followers: 22)
CLEAN - Soil, Air, Water     Hybrid Journal   (Followers: 21)
Clean Technologies     Open Access   (Followers: 1)
Clean Technologies and Environmental Policy     Hybrid Journal   (Followers: 5)
Cleanroom Technology     Full-text available via subscription   (Followers: 1)
Climate and Energy     Full-text available via subscription   (Followers: 7)
Climate Change Ecology     Open Access  
Climate Change Economics     Hybrid Journal   (Followers: 33)
Climate Policy     Hybrid Journal   (Followers: 51)
Climate Resilience and Sustainability     Open Access   (Followers: 21)
Coastal Engineering Journal     Hybrid Journal   (Followers: 9)
Cogent Environmental Science     Open Access  
Columbia Journal of Environmental Law     Open Access   (Followers: 15)
Computational Ecology and Software     Open Access   (Followers: 11)
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 5)
Conservation and Society     Open Access   (Followers: 14)
Conservation Letters     Open Access   (Followers: 51)
Conservation Science     Open Access   (Followers: 29)
Consilience : The Journal of Sustainable Development     Open Access   (Followers: 3)
Contemporary Problems of Ecology     Hybrid Journal   (Followers: 4)
Critical Reviews in Environmental Science and Technology     Hybrid Journal   (Followers: 15)
Critical Reviews in Toxicology     Hybrid Journal   (Followers: 26)
Cuadernos de Investigación Geográfica / Geographical Research Letters     Open Access  
Culture, Agriculture, Food and Environment     Hybrid Journal   (Followers: 25)
Culture, Agriculture, Food and Environment     Hybrid Journal   (Followers: 11)
Current Environmental Engineering     Hybrid Journal  
Current Environmental Health Reports     Hybrid Journal   (Followers: 2)
Current Forestry Reports     Hybrid Journal   (Followers: 1)
Current Landscape Ecology Reports     Hybrid Journal   (Followers: 2)
Current Opinion in Environmental Science & Health     Hybrid Journal   (Followers: 1)
Current Opinion in Environmental Sustainability     Hybrid Journal   (Followers: 17)
Current Research in Ecological and Social Psychology     Open Access  
Current Research in Environmental Sustainability     Open Access   (Followers: 2)
Current Research in Green and Sustainable Chemistry     Open Access   (Followers: 1)
Current Research in Microbiology     Open Access   (Followers: 27)
Current Sustainable/Renewable Energy Reports     Hybrid Journal   (Followers: 9)
Current World Environment     Open Access   (Followers: 7)
Developments in Atmospheric Science     Full-text available via subscription   (Followers: 31)
Developments in Earth and Environmental Sciences     Full-text available via subscription   (Followers: 3)
Developments in Earth Surface Processes     Full-text available via subscription   (Followers: 1)
Developments in Environmental Modelling     Full-text available via subscription   (Followers: 8)
Developments in Environmental Science     Full-text available via subscription   (Followers: 4)
Developments in Integrated Environmental Assessment     Full-text available via subscription   (Followers: 5)
Die Bodenkultur : Journal of Land Management, Food and Environment     Open Access   (Followers: 2)
Disaster Prevention and Management     Hybrid Journal   (Followers: 32)
Discover Sustainability     Open Access   (Followers: 3)
disP - The Planning Review     Hybrid Journal   (Followers: 1)
Divulgación Científica     Open Access   (Followers: 1)
Drug and Chemical Toxicology     Hybrid Journal   (Followers: 16)
Duke Environmental Law & Policy Forum     Open Access   (Followers: 7)
Dynamiques Environnementales     Open Access   (Followers: 1)
E3S Web of Conferences     Open Access   (Followers: 2)
Earth and Environmental Science Transactions of the Royal Society of Edinburgh     Hybrid Journal   (Followers: 6)
Earth Interactions     Open Access   (Followers: 13)
Earth Science Informatics     Hybrid Journal   (Followers: 5)
Earth System Governance     Open Access  
Earth System Science Data (ESSD)     Open Access   (Followers: 8)
Earth Systems and Environment     Hybrid Journal   (Followers: 3)
Earthquake Science     Hybrid Journal   (Followers: 14)
EchoGéo     Open Access  
Eco-Thinking     Open Access   (Followers: 5)
Ecocycles     Open Access   (Followers: 6)
Ecohydrology     Hybrid Journal   (Followers: 11)
Ecohydrology & Hydrobiology     Full-text available via subscription   (Followers: 4)
Ecologia Aplicada     Open Access  
Ecología en Bolivia     Open Access  
Ecological Applications     Full-text available via subscription   (Followers: 213)
Ecological Chemistry and Engineering S     Open Access   (Followers: 4)
Ecological Complexity     Hybrid Journal   (Followers: 7)
Ecological Engineering     Hybrid Journal   (Followers: 4)
Ecological Engineering : X     Open Access  
Ecological Indicators     Hybrid Journal   (Followers: 23)
Ecological Informatics     Hybrid Journal   (Followers: 4)
Ecological Management & Restoration     Hybrid Journal   (Followers: 15)
Ecological Modelling     Hybrid Journal   (Followers: 96)
Ecological Monographs     Full-text available via subscription   (Followers: 39)
Ecological Processes     Open Access   (Followers: 2)
Ecological Questions     Open Access   (Followers: 4)
Ecological Research     Hybrid Journal   (Followers: 12)
Ecological Restoration     Full-text available via subscription   (Followers: 23)
Ecologist, The     Full-text available via subscription   (Followers: 23)
Ecology     Full-text available via subscription   (Followers: 481)
Ecology and Evolution     Open Access   (Followers: 104)
Ecology Letters     Hybrid Journal   (Followers: 341)
EcoMat : Functional Materials for Green Energy and Environment     Open Access   (Followers: 3)
Economics and Policy of Energy and the Environment     Full-text available via subscription   (Followers: 14)
Économie rurale     Open Access   (Followers: 3)
Ecoprint : An International Journal of Ecology     Open Access   (Followers: 6)
Ecopsychology     Hybrid Journal   (Followers: 8)
Ecosphere     Open Access   (Followers: 9)
Ecosystem Services     Hybrid Journal   (Followers: 10)
Ecosystems     Hybrid Journal   (Followers: 33)
Ecosystems and People     Open Access   (Followers: 3)

        1 2 3 4 5 | Last

Similar Journals
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Clean Technologies
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Online) 2571-8797
Published by MDPI Homepage  [238 journals]
  • Clean Technol., Vol. 3, Pages 670-684: Hybrid Hydrogen–PV–e-Mobility
           Industrial Energy Community Concept—A Technology Feasibility Study

    • Authors: Istvan Vokony
      First page: 670
      Abstract: As renewable energy sources are spreading, the problems of energy usage, transport and storage arise more frequently. In order that the performance of energy producing units from renewable sources, which have a relatively low efficiency, should not be decreased further, and to promote sustainable energy consumption solutions, a living lab conception was elaborated in this project. At the pilot site, the produced energy (by PV panels, gas turbines/engines) is stored in numerous ways, including hydrogen production. The following uses of hydrogen are explored: (i) feeding it into the national natural gas network; (ii) selling it at a H-CNG (compressed natural gas) filling station; (iii) using it in fuel cells to produce electricity. This article introduces the overall implementation plan, which can serve as a model for the hybrid energy communities to be established in the future.
      Citation: Clean Technologies
      PubDate: 2021-09-22
      DOI: 10.3390/cleantechnol3040040
      Issue No: Vol. 3, No. 4 (2021)
  • Clean Technol., Vol. 3, Pages 685-698: Integrated and Metal Free Synthesis
           of Dimethyl Carbonate and Glycidol from Glycerol Derived
           1,3-Dichloro-2-propanol via CO2 Capture

    • Authors: Santosh Khokarale, Ganesh Shelke, Jyri-Pekka Mikkola
      First page: 685
      Abstract: Dimethyl carbonate (DMC) and glycidol are considered industrially important chemical entities and there is a great benefit if these moieties can be synthesized from biomass-derived feedstocks such as glycerol or its derivatives. In this report, both DMC and glycidol were synthesized in an integrated process from glycerol derived 1,3-dichloro-2-propanol and CO2 through a metal-free reaction approach and at mild reaction conditions. Initially, the chlorinated cyclic carbonate, i.e., 3-chloro-1,2-propylenecarbonate was synthesized using the equivalent interaction of organic superbase 1,8-diazabicyclo [5.4.0] undec-7-ene (DBU) and 1,3-dichloro-2-propanol with CO2 at room temperature. Further, DMC and glycidol were synthesized by the base-catalyzed transesterification of 3-chloro-1,2-propylenecarbonate using DBU in methanol. The synthesis of 3-chloro-1,2-propylenecarbonate was performed in different solvents such as dimethyl sulfoxide (DMSO) and 2-methyltetrahydrofuran (2-Me-THF). In this case, 2-Me-THF further facilitated an easy separation of the product where a 97% recovery of the 3-chloro-1,2-propylenecarbonate was obtained compared to 63% with DMSO. The use of DBU as the base in the transformation of 3-chloro-1,2-propylenecarbonate further facilitates the conversion of the 3-chloro-1,2 propandiol that forms in situ during the transesterification process. Hence, in this synthetic approach, DBU not only eased the CO2 capture and served as a base catalyst in the transesterification process, but it also performed as a reservoir for chloride ions, which further facilitates the synthesis of 3-chloro-1,2-propylenecarbonate and glycidol in the overall process. The separation of the reaction components proceeded through the solvent extraction technique where a 93 and 89% recovery of the DMC and glycidol, respectively, were obtained. The DBU superbase was recovered from its chlorinated salt, [DBUH][Cl], via a neutralization technique. The progress of the reactions as well as the purity of the recovered chemical species was confirmed by means of the NMR analysis technique. Hence, a single base, as well as a renewable solvent comprising an integrated process approach was carried out under mild reaction conditions where CO2 sequestration along with industrially important chemicals such as dimethyl carbonate and glycidol were synthesized.
      Citation: Clean Technologies
      PubDate: 2021-09-24
      DOI: 10.3390/cleantechnol3040041
      Issue No: Vol. 3, No. 4 (2021)
  • Clean Technol., Vol. 3, Pages 699-710: Comparative Life Cycle Assessment
           of EPA and DHA Production from Microalgae and Farmed Fish

    • Authors: Sarat Chandra Togarcheti, Ramesh Babu Padamati
      First page: 699
      Abstract: The present study aims at comparing the life cycle environmental impacts of polyunsaturated fatty acids production (PUFA) from microalgae and farmed fish. PUFA production from microalgae cultivated via heterotrophy and photoautotrophy was assessed and compared. The primary energy demand (PED) and environmental impacts (EI) of PUFA production from microalgae via heterotrophy were significantly lower compared to PUFA produced via photoautotrophy. Furthermore, PED and EI of PUFA production from fish farmed in marine net pens were assessed. The results indicated that the PED and EI of PUFA production from farmed fish are higher than that produced from microalgae cultivated via heterotrophy. Therefore, the results suggest that PUFA produced from microalgae via heterotrophy could substitute fish oil from an environmental perspective. Furthermore, life cycle analysis results indicate that PUFA derived from microalgae could potentially replace fish oil in the fish feed, thus reducing the pressure on oceans.
      Citation: Clean Technologies
      PubDate: 2021-09-28
      DOI: 10.3390/cleantechnol3040042
      Issue No: Vol. 3, No. 4 (2021)
  • Clean Technol., Vol. 3, Pages 711-742: Key Targets for Improving Algal
           Biofuel Production

    • Authors: Gareth Griffiths, Abul Kalam Hossain, Vikas Sharma, Ganesh Duraisamy
      First page: 711
      Abstract: A number of technological challenges need to be overcome if algae are to be utilized for commercial fuel production. Current economic assessment is largely based on laboratory scale up or commercial systems geared to the production of high value products, since no industrial scale plant exits that are dedicated to algal biofuel. For macroalgae (‘seaweeds’), the most promising processes are anaerobic digestion for biomethane production and fermentation for bioethanol, the latter with levels exceeding those from sugar cane. Currently, both processes could be enhanced by increasing the rate of degradation of the complex polysaccharide cell walls to generate fermentable sugars using specifically tailored hydrolytic enzymes. For microalgal biofuel production, open raceway ponds are more cost-effective than photobioreactors, with CO2 and harvesting/dewatering costs estimated to be ~50% and up to 15% of total costs, respectively. These costs need to be reduced by an order of magnitude if algal biodiesel is to compete with petroleum. Improved economics could be achieved by using a low-cost water supply supplemented with high glucose and nutrients from food grade industrial wastewater and using more efficient flocculation methods and CO2 from power plants. Solar radiation of not <3000 h·yr−1 favours production sites 30° north or south of the equator and should use marginal land with flat topography near oceans. Possible geographical sites are discussed. In terms of biomass conversion, advances in wet technologies such as hydrothermal liquefaction, anaerobic digestion, and transesterification for algal biodiesel are presented and how these can be integrated into a biorefinery are discussed.
      Citation: Clean Technologies
      PubDate: 2021-10-09
      DOI: 10.3390/cleantechnol3040043
      Issue No: Vol. 3, No. 4 (2021)
  • Clean Technol., Vol. 3, Pages 743-760: Estimating Smart Wi-Fi
           Thermostat-Enabled Thermal Comfort Control Savings for Any Residence

    • Authors: Abdulelah D. Alhamayani, Qiancheng Sun, Kevin P. Hallinan
      First page: 743
      Abstract: Nowadays, most indoor cooling control strategies are based solely on the dry-bulb temperature, which is not close to a guarantee of thermal comfort of occupants. Prior research has shown cooling energy savings from use of a thermal comfort control methodology ranging from 10 to 85%. The present research advances prior research to enable thermal comfort control in residential buildings using a smart Wi-Fi thermostat. “Fanger’s Predicted Mean Vote model” is used to define thermal comfort. A machine learning model leveraging historical smart Wi-Fi thermostat data and outdoor temperature is trained to predict indoor temperature. A Long Short-Term-Memory neural network algorithm is employed for this purpose. The model considers solar heat input estimations to a residence as input features. The results show that this approach yields a substantially improved ability to accurately model and predict indoor temperature. Secondly, it enables a more accurate estimation of potential savings from thermal comfort control. Cooling energy savings ranging from 33 to 47% are estimated based upon real data for variable energy effectiveness and solar exposed residences.
      Citation: Clean Technologies
      PubDate: 2021-10-12
      DOI: 10.3390/cleantechnol3040044
      Issue No: Vol. 3, No. 4 (2021)
  • Clean Technol., Vol. 3, Pages 519-533: Sensing and Delineating Mixed-VOC
           Composition in the Air Using a Single Metal Oxide Sensor

    • Authors: Govind S. Thakor, Ning Zhang, Rafael M. Santos
      First page: 519
      Abstract: Monitoring volatile organic compounds (VOCs) places a crucial role in environmental pollutants control and indoor air quality. In this study, a metal-oxide (MOx) sensor detector (used in a commercially available monitor) was employed to delineate the composition of air containing three common VOCs (ethanol, acetone, and hexane) under various concentrations. Experiments with a single component and double components were conducted to investigate how the solvents interact with the metal oxide sensor. The experimental results revealed that the affinity between VOC and sensor was in the following order: acetone > ethanol > n-hexane. A mathematical model was developed, based on the experimental findings and data analysis, to convert the output resistance value of the sensor into concentration values, which, in turn, can be used to calculate a VOC-based air quality index. Empirical equations were established based on inferences of vapour composition versus resistance trends, and on an approach of using original and diluted air samples to generate two sets of resistance data per sample. The calibration of numerous model parameters allowed matching simulated curves to measured data. Therefore, the predictive mathematical model enabled quantifying the total concentration of sensed VOCs, in addition to estimating the VOC composition. This first attempt to obtain semiquantitative data from a single MOx sensor, despite the remaining selectivity challenges, is aimed at expanding the capability of mobile air pollutants monitoring devices.
      Citation: Clean Technologies
      PubDate: 2021-07-13
      DOI: 10.3390/cleantechnol3030031
      Issue No: Vol. 3, No. 3 (2021)
  • Clean Technol., Vol. 3, Pages 534-536: Clean Technol. 2021 Young
           Investigator Award: Announcement and Interview with the Winner

    • Authors: Clean Technologies Editorial Office Clean Technologies Editorial Office
      First page: 534
      Abstract: After an extensive voting period, we are pleased to present the winner of the Clean Technol [...]
      Citation: Clean Technologies
      PubDate: 2021-07-19
      DOI: 10.3390/cleantechnol3030032
      Issue No: Vol. 3, No. 3 (2021)
  • Clean Technol., Vol. 3, Pages 537-562: Investigation of Performance and
           Emission Parameters of Hydroxygen (HHO)-Enriched Diesel Fuel with Water
           Injection in the Compression Ignition Engine

    • Authors: Romualdas Juknelevičius, Alfredas Rimkus, Saugirdas Pukalskas, Stanislaw Szwaja
      First page: 537
      Abstract: The development of engine technologies and research on combustion processes are focused on finding new generation CI engines with simple control of the combustion process while efficiently maintaining desirable engine performance and meeting emission regulations. This comprehensive study on the relatively low hydrogen energy fraction (0.65–1.80%), supplied by onboard water electrolysers and on water injection, was performed on the performance and emission parameters of the CI engine. The article presents results of both experiment and simulation about the effect of hydroxygen and water injection on the combustion process, auto-ignition delay, combustion intensity, the temperature of the mixture and engine performance at BMEP of 0.2 MPa, 0.4 MPa, 0.6 MPa, and 0.8 MPa at a speed of 1900 rpm. For the first part, the test engine operated with diesel fuel with 3.5 L/min of hydroxygen gas supplied with an external mixture formation. The HHO has an effect on the combustion process at all range of BMEP. A decrease in BTE and increase in BSFC were noticed during tests. The peak pressure and the rate of heat release decreased, but the NOx decreased as well. The second part of experiment was performed with the injection of a substantial amount of water, 8.4–17.4 kg/h (140–290 cm3/min), and the same amount of hydroxygen. The injection of water further decreased the NOx; therefore, HHO and WI can be used to meet emission regulations. A simulation of the combustion process was carried out with the AVL BOOST sub-program BURN. The AVL BOOST simulation provided a detailed view of the in-cylinder pressure, pressure-rise, combustion intensity shape parameter and SOC.
      Citation: Clean Technologies
      PubDate: 2021-07-26
      DOI: 10.3390/cleantechnol3030033
      Issue No: Vol. 3, No. 3 (2021)
  • Clean Technol., Vol. 3, Pages 563-580: Carbon Storage in Portland Cement
           Mortar: Influences of Hydration Stage, Carbonation Time and Aggregate

    • Authors: Luqman Kolawole Abidoye, Diganta B. Das
      First page: 563
      Abstract: This study elucidates the effects of the particle size, carbonation time, curing time and pressure on the efficiency of carbon storage in Portland cement mortar. Using pressure chamber experiments, our findings show how carbonation efficiency increases with a decrease in the particle size. Approximately 6.4% and 8.2% (w/w) carbonations were achieved in the coarse-sand and fine-sand based mortar samples, respectively. For the hydration/curing time of 7 h, up to 12% carbonation was achieved. This reduced to 8.2% at 40 h curing period. On the pressure effect, for comparable curing conditions, 2 bar at 7 h carbonation time gives 1.4% yield, and 8.2% at 5 bar. Furthermore, analysing the effect of the carbonation time, under comparable conditions, shows that 4 h of carbonation time gives up to 8.2% yield while 64 h of carbonation gives up to 18.5%. It can be reliably inferred that, under similar conditions, carbonation efficiency increases with lower-sized particles or higher-surface areas, increases with carbonation time and higher pressure but decreases with hydration/curing time. Microstructural analyses with X-ray diffraction (XRD) and scanning electron microscopy (SEM) further show the visual disappearance of calcium-silicate-hydrate (C-S-H) together with the inhibition of ettringite formation by the presence of CO2 and CaCO3 formation during carbonation.
      Citation: Clean Technologies
      PubDate: 2021-07-30
      DOI: 10.3390/cleantechnol3030034
      Issue No: Vol. 3, No. 3 (2021)
  • Clean Technol., Vol. 3, Pages 581-593: Innovative Energy-Recovery Unit for
           the LED-Lighting System of Heavy-Duty Vehicles

    • Authors: Nena Apostolidou, Fotis Valsamas, Dimitris Baros, Michael Loupis, Vasilios Dasteridis, Charalampos Kokkinis
      First page: 581
      Abstract: In this work, the development of an energy recovery control unit to be incorporated in the light-emitting diodes (LEDs) lighting systems of heavy-duty vehicles is presented. This innovative industrial product adopts modern power electronics technology to improve existing trucks’ LED lighting system by eliminating the so far inevitable power consumption by the conventional central control unit of the majority of these vehicles, which is obligatory for the uninterruptable operation of their lighting system. The main idea of this innovative product is its capability to virtually increase the lighting system power consumption without actually consuming this amount of energy, thus facilitating the central control unit requirements regarding these vehicles in an energy-conscious way. Under this light, a mature power converter’s topology is employed to draw the proper amounts of power from the vehicle’s batteries supply, to the level that the central control unit recognizes, and return this energy back to the batteries. The tests results of the developed industrial product highlight the energy saving potential of the proposed energy recovery scheme, while the Life Cycle Cost Analysis (LCCA) results confirm its techno-economical and environmental profit for the truck applications under study.
      Citation: Clean Technologies
      PubDate: 2021-08-04
      DOI: 10.3390/cleantechnol3030035
      Issue No: Vol. 3, No. 3 (2021)
  • Clean Technol., Vol. 3, Pages 594-617: Techno-Economic Assessment of IGCC
           Power Plants Using Gas Switching Technology to Minimize the Energy Penalty
           of CO2 Capture

    • Authors: Szabolcs Szima, Carlos Arnaiz del Pozo, Schalk Cloete, Szabolcs Fogarasi, Ángel Jiménez Álvaro, Ana-Maria Cormos, Calin-Cristian Cormos, Shahriar Amini
      First page: 594
      Abstract: Cost-effective CO2 capture and storage (CCS) is critical for the rapid global decarbonization effort recommended by climate science. The increase in levelized cost of electricity (LCOE) of plants with CCS is primarily associated to the large energy penalty involved in CO2 capture. This study therefore evaluates three high-efficiency CCS concepts based on integrated gasification combined cycles (IGCC): (1) gas switching combustion (GSC), (2) GSC with added natural gas firing (GSC-AF) to increase the turbine inlet temperature, and (3) oxygen production pre-combustion (OPPC) that replaces the air separation unit (ASU) with more efficient gas switching oxygen production (GSOP) reactors. Relative to a supercritical pulverized coal benchmark, these options returned CO2 avoidance costs of 37.8, 22.4 and 37.5 €/ton (including CO2 transport and storage), respectively. Thus, despite the higher fuel cost and emissions associated with added natural gas firing, the GSC-AF configuration emerged as the most promising solution. This advantage is maintained even at CO2 prices of 100 €/ton, after which hydrogen firing can be used to avoid further CO2 cost escalations. The GSC-AF case also shows lower sensitivity to uncertain economic parameters such as discount rate and capacity factor, outperforms other clean energy benchmarks, offers flexibility benefits for balancing wind and solar power, and can achieve significant further performance gains from the use of more advanced gas turbine technology. Based on all these insights, the GSC-AF configuration is identified as a promising solution for further development.
      Citation: Clean Technologies
      PubDate: 2021-08-10
      DOI: 10.3390/cleantechnol3030036
      Issue No: Vol. 3, No. 3 (2021)
  • Clean Technol., Vol. 3, Pages 618-628: Investigating Combustion Process of
           N-Butanol-Diesel Blends in a Diesel Engine with Variable Compression Ratio

    • Authors: György Szabados, Kristóf Lukács, Ákos Bereczky
      First page: 618
      Abstract: The search for alternative fuels for internal combustion engines is ongoing. Among the alternatives, plant-based fuels can also be mentioned. Alcohol is not a common fuel for diesel engines because the physical and chemical properties of the alcohols are closer to those of gasoline. In our research, the combustion properties of diesel-n-butanol mixtures have been investigated to obtain results on the effect of butanol blending on combustion. Among the combustion properties, ignition delay, in-cylinder pressure, and heat release rate can be mentioned. They have been observed under different compression conditions on an engine on which the compression ratio can be adjusted. The method used was a quite simple one, so the speed of the engine was set to a constant 900 rpm without load, while three compression ratios (19.92, 15.27, and 12.53) were adjusted with a fuel flow rate of 13 mL/min and the pre-injection angle of 18° BTDC. Blending butanol into the investigated fuel does not significantly affect maximal values of indicated pressure, while much more effect on the pressure rising rate can be detected. Furthermore, heat release rate and ignition delay increased at every compression ratio investigated. Despite the low blending rates of butanol in the mixtures, butanol significantly affects the combustion parameters, especially at high compression ratios.
      Citation: Clean Technologies
      PubDate: 2021-08-20
      DOI: 10.3390/cleantechnol3030037
      Issue No: Vol. 3, No. 3 (2021)
  • Clean Technol., Vol. 3, Pages 629-655: Resilient Predictive Control
           Coupled with a Worst-Case Scenario Approach for a
           Distributed-Generation-Rich Power Distribution Grid

    • Authors: Nouha Dkhili, Julien Eynard, Stéphane Thil, Stéphane Grieu
      First page: 629
      Abstract: In a context of accelerating deployment of distributed generation in power distribution grid, this work proposes an answer to an important and urgent need for better management tools in order to ‘intelligently’ operate these grids and maintain quality of service. To this aim, a model-based predictive control (MPC) strategy is proposed, allowing efficient re-routing of power flows using flexible assets, while respecting operational constraints as well as the voltage constraints prescribed by ENEDIS, the French distribution grid operator. The flexible assets used in the case study—a low-voltage power distribution grid in southern France—are a biogas plant and a water tower. Non-parametric machine-learning-based models, i.e., Gaussian process regression (GPR) models, are developed for intraday forecasting of global horizontal irradiance (GHI), grid load, and water demand, to better anticipate emerging constraints. The forecasts’ quality decreases as the forecast horizon grows longer, but quickly stabilizes around a constant error value. Then, the impact of forecasting errors on the performance of the control strategy is evaluated, revealing a resilient behaviour where little degradation is observed in terms of performance and computation cost. To enhance the strategy’s resilience and minimise voltage overflow, a worst-case scenario approach is proposed for the next time step and its contribution is examined. This is the main contribution of the paper. The purpose of the min–max problem added upstream of the main optimisation problem is to both anticipate and minimise the voltage overshooting resulting from forecasting errors. In this min–max problem, the feasible space defined by the confidence intervals of the forecasts is searched, in order to determine the worst-case scenario in terms of constraint violation, over the next time step. Then, such information is incorporated into the decision-making process of the main optimisation problem. Results show that these incidents are indeed reduced thanks to the min–max problem, both in terms of frequency of their occurrence and the total surface area of overshooting.
      Citation: Clean Technologies
      PubDate: 2021-08-30
      DOI: 10.3390/cleantechnol3030038
      Issue No: Vol. 3, No. 3 (2021)
  • Clean Technol., Vol. 3, Pages 656-669: Production of Green Biorefinery
           Protein Concentrate Derived from Perennial Ryegrass as an Alternative Feed
           for Pigs

    • Authors: Rajeev Ravindran, Sybrandus Koopmans, Johan P. M. Sanders, Helena McMahon, James Gaffey
      First page: 656
      Abstract: Perennial rye grass is a widely used forage species in Ireland, on which the ruminant sector of agriculture is heavily dependent. While this species of grass is the primary source of fodder for cows, it is also abundant in plant protein, which could form a potential alternative ingredient in monogastric animal feed using a green biorefinery approach. In this study, perennial rye grass was processed using a novel biorefining process to extract value added products including protein as a potential replacement for soybean meal in monogastric feeds. Feed trials were conducted on a commercial farm with 55 weaner pigs for 31 days until slaughter. The diets comprised a control and a trial diet which integrated the green biorefinery protein concentrate. The effects of the new diet were determined by measuring the daily feed intake (DFI), average weight gain (AWG) and feed conversion ratio (FCR). Amino acid profiles of grass protein concentrate and soybean meal were comparable, with the latter having a slightly higher amount of total protein content, lysine and cysteine. The DFI and ADW indicated that the treatment diet was superior to the control. DFI for the treatment diet (1.512 kg/d) was 8% higher than the control diet (1.400 kg/d) by the end of the trial. Additionally, the ADW for the treatment diet was 6.44% higher than that achieved in the control sample. Meanwhile, FCR calculations indicated that the treatment diet is just as efficient as the conventional diet. Overall, the results of the study indicate positive potential for perennial ryegrass-derived green biorefinery protein concentrate as an alternative protein source for pig feed formulations in Ireland.
      Citation: Clean Technologies
      PubDate: 2021-09-14
      DOI: 10.3390/cleantechnol3030039
      Issue No: Vol. 3, No. 3 (2021)
  • Clean Technol., Vol. 3, Pages 288-298: Facile Elaboration of Wet Cellulose
           Film as Catalyst Support of MnOx Nanoparticles for the Catalytic Oxidation
           of Dyes in Absence of Light

    • Authors: Larissa V. F. Oliveira, Lionel Limousy, Simona Bennici, Ludovic Josien, Samar Hajjar-Garreau, Mary-Lorène Goddard, Marcos A. Bizeto, Fernanda F. Camilo
      First page: 288
      Abstract: In the present work a remarkably simple procedure for the elaboration of wet cellulose film containing manganese oxide nanoparticles was developed. The films were produced using a mold made by 3D printing using cellulose dissolved in an ionic liquid, which allows the production of thin and homogeneous films of different shapes, types and designs which cannot be made using conventional techniques. Thanks to this possibility, the final catalytic object can be implemented in specific reactors. Manganese oxide nanoparticles were prepared as a colloidal solution by a redox/sol-gel procedure and then deposited on the cellulose films by wet impregnation. The catalytic film obtained was tested in the decomposition of a dye, indigo carmine (IC), in the absence of light. The influence of the pH of the solution on the decomposition rate was investigated. IC total decomposition was measured after 1-h reaction at pH below 3. At pH = 2, no deactivation of the catalyst was observed even after four decomposition cycles. This work provides a new strategy to design cellulose-based catalysts for dye removal from wastewater.
      Citation: Clean Technologies
      PubDate: 2021-03-31
      DOI: 10.3390/cleantechnol3020016
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 299-310: Renewable Energy at Home: A Look
           into Purchasing a Wind Turbine for Home Use—The Cost of Blindly Relying
           on One Tool in Decision Making

    • Authors: Sheridan Ribbing, George Xydis
      First page: 299
      Abstract: Small-scale wind turbines simulations are not as accurate when it comes to costs as compared to the large-scale wind turbines, where costs are more or less standard. In this paper, an analysis was done on a decision for a wind turbine investment in Bellingham, Whatcom County, Washington. It was revealed that a decision taken based only on a software tool could be destructive for the sustainability of a project, since not taking into account specific taxation, net metering, installation, maintenance costs, etc., beyond the optimization that the tool offers, can hide the truth.
      Citation: Clean Technologies
      PubDate: 2021-04-01
      DOI: 10.3390/cleantechnol3020017
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 311-334: Comparative Study of a Clean
           Technology Based on DSF Use in Occupied Buildings for Improving Comfort in

    • Authors: Eusébio Conceição, João Gomes, Maria Manuela Lúcio, Maria Inês Conceição, Hazim Awbi
      First page: 311
      Abstract: This paper presents a comparative study of a clean technology based on a DSF (double skin facade) used in winter conditions in the occupied buildings comfort improvement, namely the thermal comfort and air quality. The performance of a solar DSF system, the building’s thermal response, the internal thermal comfort and the internal air quality are evaluated. In this study, a DSF system, an air transport system and a HVAC (heating, ventilating and air conditioning) system based on mixing ventilation are used. The study considers a virtual chamber occupied by eight persons and equipped, in the outside environment, by three DSFs. A new horary pre-programming control methodology is developed and applied when the airflow rate is constant and the number of DSFs to operate is variable, when the airflow rate is variable and the number of DSFs to operate is constant and when the airflow rate is variable and the number of DSFs to operate is variable. This work uses a numerical model that simulates the integral building thermal behavior and an integral human thermal response. The internal air, provided by a mixing ventilating system, is warmed using the DSF system. The air temperature inside the DSF system and the virtual chamber, the thermal comfort level using the PMV index, the internal air quality using the carbon dioxide concentration and the uncomfortable hours are calculated for winter conditions. The results obtained show that the energy produced in the DSF, using solar radiation, guarantees acceptable thermal comfort conditions in the morning and in the afternoon. The indoor air quality obtained at the breathing level is acceptable. It is found that the airflow rate to be used is more decisive than the DSF operating methodology. However, when a solution is chosen that combines a ventilation rate with the number of DSF to operate, both variables throughout the day can obtain simultaneously better results for indoor air quality and thermal comfort according to the standards.
      Citation: Clean Technologies
      PubDate: 2021-04-01
      DOI: 10.3390/cleantechnol3020018
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 335-350: Study of Influential Parameters of
           the Caffeine Extraction from Spent Coffee Grounds: From Brewing Coffee
           Method to the Waste Treatment Conditions

    • Authors: Alexandre Vandeponseele, Micheline Draye, Christine Piot, Gregory Chatel
      First page: 335
      Abstract: This article aims to study the interest of spent coffee grounds (SCG) valorization through caffeine recovery. In an original way, this study takes into account all the parameters such as (i) the brewing coffee methods (household, coffee shops, etc.); (ii) the storage conditions, in particular the drying step; (iii) the solid/liquid extraction parameters such as the nature of solvent, the temperature, the extraction time and the solid/liquid ratio; and (iv) the liquid/liquid purification parameters such as the nature, the volume and the pH of extraction medium. Results have shown that spent coffee grounds from coffee-shops obtained by percolation contain a higher amount of caffeine than spent coffee grounds from households obtained from spent pods or filters. A drying treatment is not required when extraction is performed under one week after the spent coffee grounds collection with 96.4% of not degraded caffeine. Solid/liquid extraction performed with 25 mL.g−1 SCG of hydroalcoholic solvent (water/EtOH, v/v 60/40) at 60 °C during 15 min have given a caffeine yield up to 4.67 mg.g−1 SCG. When using ethyl acetate, 93.4% of the caffeine has been selectively recovered by liquid/liquid extraction. Finally, the extraction of caffeine for the valorization of spent coffee grounds is a promising and easy way, which fits with an already important and well established market.
      Citation: Clean Technologies
      PubDate: 2021-04-02
      DOI: 10.3390/cleantechnol3020019
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 351-376: Hybrid PV System with High Speed
           Flywheel Energy Storage for Remote Residential Loads

    • Authors: Abid Soomro, Keith R. Pullen, Mustafa E. Amiryar
      First page: 351
      Abstract: Due to low system inertia in microgrids, frequencies may vary rapidly from the nominal value, leading to the complete blackout of the system unless there is an adequate spinning reserve available for balancing the supply with the demand load. This issue of instability in microgrids under islanded operation has attracted particular attention recently. A diesel generator is considered to be an ideal spinning reserve to provide back-up power to the load along with the renewable energy source in islanded system. However, the high maintenance cost and CO2 emissions of diesel generator are detrimental factors which have inspired searches for more cost effective and cleaner technologies. The integration of an energy storage system (ESS) in islanded system along with generator not only reduces generator maintenance costs but also reduces the CO2 emissions by limiting its operating hours. This paper proposes an islanded PV hybrid microgrid system (PVHMS) utilizing flywheel energy storage systems (FESS) as an alternative to battery technology to support the PV system and meet the peak demand of a small residential town with 100 dwellings. The diesel generator is used in the islanded system as a spinning reserve to maintain the stability of the islanded system when the PV system and flywheel storage cannot meet the load demand. Results of analysis of such a system demonstrate that flywheel energy storage technology of appropriate size offers a viable solution to support the operation of the standalone PV system. Furthermore, the reduction in CO2 emissions and fuel consumption has been quantified as compared with the case with flywheel energy storage systems which means the diesel generator but always be operating.
      Citation: Clean Technologies
      PubDate: 2021-04-20
      DOI: 10.3390/cleantechnol3020020
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 377-394: Overview of the Enablers and
           Barriers for a Wider Deployment of CSP Tower Technology in Europe

    • Authors: Fabio Maria Aprà, Sander Smit, Raymond Sterling, Tatiana Loureiro
      First page: 377
      Abstract: For years, concentrated solar power (CSP) has been considered an emerging technology that could disrupt the energy production sector. The possibility to store the electricity generated during the sunny operating hours in the form of heat enhances energy dispatchability and gives CSP a unique value proposition that conventional renewable energies cannot provide cost-efficiently since it requires the integration of costly large-scale battery systems. CSP is a cleaner technology compared to photovoltaics, but photovoltaics currently has lower overall capital costs, making it more attractive to investors and stakeholders who want to spend less money upfront. This is one of the main reasons why CSP has never really led either the electricity market or the heating one, even if its combined generation capability (heat and electricity) is globally recognized as a great advantage for a renewable technology. In this study, we analyze the reasons why CSP is not as widespread as it could be; at the same time, we look at the opportunities and the enablers for a further deployment of this technology, focusing on the European region.
      Citation: Clean Technologies
      PubDate: 2021-04-21
      DOI: 10.3390/cleantechnol3020021
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 395-408: Three-Phase State Estimation for
           Distribution-Grid Analytics

    • Authors: Karthikeyan Nainar, Florin Iov
      First page: 395
      Abstract: Power-distribution grids consist of assets such as transformers, cables, and switches, of which the proper utilization is essential for the provision of a secure and reliable power supply to end customers. Distribution-system operators (DSOs) are responsible for the operation and maintenance of these assets. Due to the increased use of renewable sources such as wind and solar, grid assets are prone to operation conditions outside safe boundaries, such as overloading, large voltage unbalance, and a rise in voltage. At present, distribution grids are poorly monitored by DSOs, and the above-mentioned problems may thereby go unnoticed until the failure of a critical asset occurs. The deployment of smart meters in distribution grids has enabled measurements of grid variables such as power, current, and voltage. However, their measurements are used only for billing purposes, and not for monitoring and improving the operating condition of distribution grids. In this paper, a state-estimation algorithm is proposed that utilizes smart-meter data for offline analysis, and estimates the loading of grid assets and power losses. Single- and three-phase state-estimation algorithms are compared through simulation studies on a real-life low-voltage distribution grid using measured smart-meter data. The three-phase state-estimation algorithm based on the nonlinear weighted least-squares method was found to be more accurate in estimating cable loading and line power losses. The proposed method is useful for DSOs to analyze power flows in their distribution grids and take necessary actions such as grid upgrades or the rerouting of power flows.
      Citation: Clean Technologies
      PubDate: 2021-05-01
      DOI: 10.3390/cleantechnol3020022
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 409-423: Developing a Hybrid Optimization

    • Authors: Ayman Awad, Hussein Abdel-Mawgoud, Salah Kamel, Abdalla A. Ibrahim, Francisco Jurado
      First page: 409
      Abstract: Distributed generation (DG) is becoming a prominent key spot for research in recent years because it can be utilized in emergency/reserve plans for power systems and power quality improvement issues, besides its drastic impact on the environment as a greenhouse gas (GHG) reducer. For maximizing the benefits from such technology, it is crucial to identify the best size and location for DG that achieves the required goal of installing it. This paper presents an investigation of the optimized allocation of DG in different modes using a proposed hybrid technique, the tunicate swarm algorithm/sine-cosine algorithm (TSA/SCA). This investigation is performed on an IEEE-69 Radial Distribution System (RDS), where the impact of such allocation on the system is evaluated by NEPLAN software.
      Citation: Clean Technologies
      PubDate: 2021-05-01
      DOI: 10.3390/cleantechnol3020023
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 424-436: Comparison of Mechanical and
           Physicochemical Characteristics of Potato Starch and Gelatine Blend
           Bioplastics Made with Gelatines from Different Sources

    • Authors: Marta Mroczkowska, David Culliton, Kieran Germaine, Adriana Neves
      First page: 424
      Abstract: Environmentally friendly packaging is becoming more popular as the number of companies implementing more sustainable solutions continues to increase, and consumers become more aware and choose more environmentally friendly options. However, not all environmentally friendly packaging meets all desirable properties, as some are only partially made of renewable raw materials or degrade over a long period of time. Bioplastics constructed from blends of gelatine and starch are solely made from renewable raw materials. Combined with relatively short degradation times, these materials have the potential to replace currently used, non-biodegradable film and single-use plastics. However, despite these advantages, further research is required to identify the best combination of raw materials, selectively and collectively, and to then optimise the appropriate physicochemical properties of the resultant bioplastics. In this study, gelatine from different sources (piscine, porcine, bovine) combined with potato starch was used to generate home-compostable bioplastics. These bioplastics were assessed in terms of water solubility, water content, opacity, surface roughness, and key mechanical properties such as tensile strength. Significant differences were found, particularly for piscine gelatine blends. It was concluded that piscine gelatine is a promising protein with highly relevant properties for the bioplastics industry.
      Citation: Clean Technologies
      PubDate: 2021-05-11
      DOI: 10.3390/cleantechnol3020024
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 437-449: Analysis of Latvian Households’
           Potential Participation in the Energy Market as Prosumers

    • Authors: Kristina Lebedeva, Andris Krumins, Antra Tamane, Egils Dzelzitis
      First page: 437
      Abstract: The European Union sets targets for the extensive use of renewable energy. Meanwhile, the energy production network is changing and transferring from the classic “producer to consumer” scheme to new operation models, where a small consumer with local renewable energy systems becomes a producer–prosumer, an active energy consumer who is also an energy producer. This study evaluated a potential of Latvian households’ participation in the energy market as prosumers. The analysis was based on an informal prospective extrapolation data evaluation method, based on real historical data from the Central Statistical Bureau of Latvia, annual reports of distribution and transmission system operators, assessments, and the conclusions of relevant experts. In addition, the real performance of a photovoltaic (PV) system was evaluated to get information on the whole year’s energy balance, and to compare it with seasonal electricity price fluctuation. The Latvian electricity transmission system is able to accept about 800 MW of additional new renewable energy source (RES) capacity, so there is a great potential for prosumers. The biggest obstacle for a household’s involvement in the energy market is the lack of support mechanisms and relatively high cost of RES technologies. The results show that with the current dynamics of new microgenerator connections, Latvia will achieve the set goals regarding the involvement of prosumers in the achievement of RES goals only in the next century. In order to attract the public to energy production, the concept of energy community needs to be defined in Latvian legislation, a balanced peer trading mechanism needs to be developed for various RES self-consumption groups willing to sell surplus electricity, and tax policy conditions need to be reviewed for electricity transactions outside the NET (payment system), in order to fully ensure the rights of prosumers.
      Citation: Clean Technologies
      PubDate: 2021-05-17
      DOI: 10.3390/cleantechnol3020025
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 450-461: Impact of Pyrolysis Oil Addition to
           Ethanol on Combustion in the Internal Combustion Spark Ignition Engine

    • Authors: Magdalena Szwaja, Mariusz Chwist, Stanislaw Szwaja, Romualdas Juknelevičius
      First page: 450
      Abstract: Thermal processing (torrefaction, pyrolysis, and gasification), as a technology can provide environmentally friendly use of plastic waste. However, it faces a problem with respect to its by-products. Pyrolysis oil obtained using this technology is seen as a substance that is extremely harmful for living creatures and that needs to be neutralized. Due to its relatively high calorific value, it can be considered as a potential fuel for internal combustion spark-ignition engines. In order make the combustion process effective, pyrolysis oil is blended with ethanol, which is commonly used as a fuel for flexible fuel cars. This article presents results from combustion tests conducted on a single-cylinder research engine at full load working at 600 rpm at a compression ratio of 9.5:1, and an equivalence ratio of 1. The analysis showed improvements in combustion and engine performance. It was found that, due to the higher calorific value of the blend, the engine possessed a higher indicated mean effective pressure. It was also found that optimal spark timing for this ethanol-pyrolysis oil blend was improved at a crank angle of 2–3° at 600 rpm. In summary, ethanol-pyrolysis oil blends at a volumetric ratio of 3:1 (25% pyrolysis oil) can successfully substitute ethanol in spark-ignition engines, particularly for vehicles with flexible fuel type.
      Citation: Clean Technologies
      PubDate: 2021-05-26
      DOI: 10.3390/cleantechnol3020026
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 462-473: A Binary Integer Programming Method
           for Optimal Wind Turbines Allocation

    • Authors: Nikolaos M. Manousakis, Constantinos S. Psomopoulos, George Ch. Ioannidis, Stavros D. Kaminaris
      First page: 462
      Abstract: The present study introduces a Binary Integer Programming (BIP) method to minimize the number of wind turbines needed to be installed in a wind farm. The locations of wind turbines are selected in a virtual grid which is constructed considering a minimum distance between the wind turbines to avoid the wake effect. Additional equality constraints are also included to the proposed formulation to prohibit or enforce the installation of wind turbines placement at specific locations of the wind farmland. Moreover, a microscopic wind turbine placement considering the local air density is studied. To verify the efficiency of this proposal, a square site was subdivided into 25 square cells providing a virtual grid with 36 candidate placement locations. Moreover, a virtual grid with 121 vertices related with a Greek island is also tested. All simulations conducted considering the area of geographical territory, the length of wind turbine blades, as well as the capacity of each turbine.
      Citation: Clean Technologies
      PubDate: 2021-06-01
      DOI: 10.3390/cleantechnol3020027
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 474-489: A Review of Heavy-Duty Vehicle
           Powertrain Technologies: Diesel Engine Vehicles, Battery Electric
           Vehicles, and Hydrogen Fuel Cell Electric Vehicles

    • Authors: Carlo Cunanan, Manh-Kien Tran, Youngwoo Lee, Shinghei Kwok, Vincent Leung, Michael Fowler
      First page: 474
      Abstract: Greenhouse gas emissions from the freight transportation sector are a significant contributor to climate change, pollution, and negative health impacts because of the common use of heavy-duty diesel vehicles (HDVs). Governments around the world are working to transition away from diesel HDVs and to electric HDVs, to reduce emissions. Battery electric HDVs and hydrogen fuel cell HDVs are two available alternatives to diesel engines. Each diesel engine HDV, battery-electric HDV, and hydrogen fuel cell HDV powertrain has its own advantages and disadvantages. This work provides a comprehensive review to examine the working mechanism, performance metrics, and recent developments of the aforementioned HDV powertrain technologies. A detailed comparison between the three powertrain technologies, highlighting the advantages and disadvantages of each, is also presented, along with future perspectives of the HDV sector. Overall, diesel engine in HDVs will remain an important technology in the short-term future due to the existing infrastructure and lower costs, despite their high emissions, while battery-electric HDV technology and hydrogen fuel cell HDV technology will be slowly developed to eliminate their barriers, including costs, infrastructure, and performance limitations, to penetrate the HDV market.
      Citation: Clean Technologies
      PubDate: 2021-06-01
      DOI: 10.3390/cleantechnol3020028
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 490-502: Carbon Capture from Biogas by Deep
           Eutectic Solvents: A COSMO Study to Evaluate the Effect of Impurities on
           Solubility and Selectivity

    • Authors: Thomas Quaid, M. Toufiq Reza
      First page: 490
      Abstract: Deep eutectic solvents (DES) are compounds of a hydrogen bond donor (HBD) and a hydrogen bond acceptor (HBA) that contain a depressed melting point compared to their individual constituents. DES have been studied for their use as carbon capture media and biogas upgrading. However, contaminants’ presence in biogas might affect the carbon capture by DES. In this study, conductor-like screening model for real solvents (COSMO-RS) was used to determine the effect of temperature, pressure, and selective contaminants on five DES’ namely, choline chloride-urea, choline chloride-ethylene glycol, tetra butyl ammonium chloride-ethylene glycol, tetra butyl ammonium bromide-decanoic acid, and tetra octyl ammonium chloride-decanoic acid. Impurities studied in this paper are hydrogen sulfide, ammonia, water, nitrogen, octamethyltrisiloxane, and decamethylcyclopentasiloxane. At infinite dilution, CO2 solubility dependence upon temperature in each DES was examined by means of Henry’s Law constants. Next, the systems were modeled from infinite dilution to equilibrium using the modified Raoults’ Law, where CO2 solubility dependence upon pressure was examined. Finally, solubility of CO2 and CH4 in the various DES were explored with the presence of varying mole percent of selective contaminants. Among the parameters studied, it was found that the HBD of the solvent is the most determinant factor for the effectiveness of CO2 solubility. Other factors affecting the solubility are alkyl chain length of the HBA, the associated halogen, and the resulting polarity of the DES. It was also found that choline chloride-urea is the most selective to CO2, but has the lowest CO2 solubility, and is the most polar among other solvents. On the other hand, tetraoctylammonium chloride-decanoic acid is the least selective, has the highest maximum CO2 solubility, is the least polar, and is the least affected by its environment.
      Citation: Clean Technologies
      PubDate: 2021-06-01
      DOI: 10.3390/cleantechnol3020029
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 503-518: Optimal Operation of Solar Powered
           Electric Vehicle Parking Lots Considering Different Photovoltaic

    • Authors: Mahsa Z. Farahmand, Sara Javadi, Sayyed Muhammad Bagher Sadati, Hannu Laaksonen, Miadreza Shafie-khah
      First page: 503
      Abstract: The performance of electric vehicles and their abilities to reduce fossil fuel consumption and air pollution on one hand and the use of photovoltaic (PV) panels in energy production, on the other hand, has encouraged parking lot operators (PLO) to participate in the energy market to gain more profit. However, there are several challenges such as different technologies of photovoltaic panels that make the problem complex in terms of installation cost, efficiency, available output power and dependency on environmental temperature. Therefore, the aim of this study is to maximize the PLO’s operational profit under the time of use energy pricing scheme by investigating the effects of different PV panel technologies on energy production and finding the best strategy for optimal operation of PVs and electric vehicle (EV) parking lots which is achieved by means of market and EV owners’ interaction. For the accurate investigation, four different PV panel technologies are considered in different seasons, with significant differences in daylight times, in Helsinki, Finland.
      Citation: Clean Technologies
      PubDate: 2021-06-16
      DOI: 10.3390/cleantechnol3020030
      Issue No: Vol. 3, No. 2 (2021)
  • Clean Technol., Vol. 3, Pages 1-18: Kolbe Electrolysis for the Conversion
           of Carboxylic Acids to Valuable Products—A Process Design Study

    • Authors: Daniel Klüh, Wolfgang Waldmüller, Matthias Gaderer
      First page: 1
      Abstract: The substitution of fossil resources by renewable alternatives is a major challenge for our society. Kolbe electrolysis converts carboxylic acids to hydrocarbons, which can be used as base chemicals, specialty chemicals, or fuels. Carboxylic acids may be retrieved from biomass or residues and, in consequence, can be a sustainable feedstock. Since the Kolbe electrolysis has only been investigated in lab scale, this work proposes the first basic engineering design study on process development for a continuously working process. Thermophysical data, including solubility and boiling point, are used to gain insight into requirements on process equipment such as separation processes or process parameters such as operating temperature. Furthermore, Aspen Plus was used to retrieve information on acid base equilibria and azeotropes. The process development for three different feedstocks (acetic acid, valeric acid and lauric acid) was performed. The process design shows that most of the process units are rather straightforward and rely on state of the art technologies. The addition of an alkaline catalyst improves the solubility and deprotonation of the carboxylic acid but on the cost of a possibly lower product selectivity. Elevation of the operating temperature above the Krafft point is necessary for long-chain fatty acids. Kolbe electrolysis can be an interesting technology for future production processes based on carboxylic acids and electricity from sustainable sources.
      Citation: Clean Technologies
      PubDate: 2021-01-02
      DOI: 10.3390/cleantechnol3010001
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 19-36: Economic and Sustainability of
           Biodiesel Production—A Systematic Literature Review

    • Authors: Tamás Mizik, Gábor Gyarmati
      First page: 19
      Abstract: As Earth’s fossil energy resources are limited, there is a growing need for renewable resources such as biodiesel. That is the reason why the social, economic and environmental impacts of biofuels became an important research topic in the last decade. Depleted stocks of crude oil and the significant level of environmental pollution encourage researchers and professionals to seek and find solutions. The study aims to analyze the economic and sustainability issues of biodiesel production by a systematic literature review. During this process, 53 relevant studies were analyzed out of 13,069 identified articles. Every study agrees that there are several concerns about the first-generation technology; however, further generations cannot be price-competitive at this moment due to the immature technology and high production costs. However, there are promising alternatives, such as wastewater-based microalgae with up to 70% oil content, fat, oils and grease (FOG), when production cost is below 799 USD/gallon, and municipal solid waste-volatile fatty acids technology, where the raw material is free. Proper management of the co-products (mainly glycerol) is essential, especially at the currently low petroleum prices (0.29 USD/L), which can only be handled by the biorefineries. Sustainability is sometimes translated as cost efficiency, but the complex interpretation is becoming more common. Common elements of sustainability are environmental and social, as well as economic, issues.
      Citation: Clean Technologies
      PubDate: 2021-01-08
      DOI: 10.3390/cleantechnol3010002
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 37-58: Interphase Power Flow Control via
           Single-Phase Elements in Distribution Systems

    • Authors: Piyapath Siratarnsophon, Vinicius C. Cunha, Nicholas G. Barry, Surya Santoso
      First page: 37
      Abstract: The capability of routing power from one phase to another, interphase power flow (IPPF) control, has the potential to improve power systems efficiency, stability, and operation. To date, existing works on IPPF control focus on unbalanced compensation using three-phase devices. An IPPF model is proposed for capturing the general power flow caused by single-phase elements. The model reveals that the presence of a power quantity in line-to-line single-phase elements causes an IPPF of the opposite quantity; line-to-line reactive power consumption causes real power flow from leading to lagging phase while real power consumption causes reactive power flow from lagging to leading phase. Based on the model, the IPPF control is proposed for line-to-line single-phase power electronic interfaces and static var compensators (SVCs). In addition, the control is also applicable for the line-to-neutral single-phase elements connected at the wye side of delta-wye transformers. Two simulations on a multimicrogrid system and a utility feeder are provided for verification and demonstration. The application of IPPF control allows single-phase elements to route active power between phases, improving system operation and flexibility. A simple IPPF control for active power balancing at the feeder head shows reductions in both voltage unbalances and system losses.
      Citation: Clean Technologies
      PubDate: 2021-01-13
      DOI: 10.3390/cleantechnol3010003
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 59-78: Community Based Pollution Prevention
           for Two Urban Cities—A Case Study

    • Authors: Jay N. Meegoda, Daniel Watts, Hsin-Neng Hsieh, Bruno Bezerra de Souza
      First page: 59
      Abstract: Pollution prevention is an approach for generating less waste using fewer toxic chemicals while conserving water and energy. Even though pollution prevention practices have been encouraged for over thirty years, many smaller businesses have not considered or adopted such techniques. This study examines the effect of a community-based approach designed to emphasize the benefits to the health and economic well-being of urban communities when source reduction practices are implemented by businesses in the community. Partnering with existing community groups in Newark and Jersey City, NJ, technical assistance was provided to small and medium-sized businesses under grant funding from Region 2 of the US Environmental Protection Agency. In this research, 32 small and medium-sized businesses were evaluated for source reduction opportunities and implementation plans were drawn up. After these businesses implemented operational changes, emission and cost savings were determined and reported back to respective small business owners as well as to the communities during community meetings designed to encourage additional participation. Based on 32 case studies, several measurable benefits were achieved, including the yearly saving of 932 pounds of hazardous waste, 3917 pounds of non-hazardous waste, 13.62 metric tons of carbon equivalent (MTCE) of greenhouse gases and $5335 USD. The initial findings suggest that community-based programs such as this can be beneficial but must be sustained over a period of time. One issue that was repeatedly observed, and is likely widely believed, is the concern of small business operators that cooperation with any group funded by a government program may lead to the assessment of fines or penalties for environmental violations. This concern limits the willingness of many smaller businesses to participate. The findings of this study suggest that a sustained community-based program may overcome that concern through demonstration of the benefit to the business and the community, and through credibility building achieved by regular community reporting and the absence of official intervention.
      Citation: Clean Technologies
      PubDate: 2021-01-20
      DOI: 10.3390/cleantechnol3010004
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 79-80: Acknowledgment to Reviewers of Clean
           Technologies in 2020

    • Authors: Clean Technologies Editorial Office Clean Technologies Editorial Office
      First page: 79
      Abstract: Peer review is the driving force of journal development, and reviewers are gatekeepers who ensure that Clean Technologies maintains its standards for the high quality of its published papers [...]
      Citation: Clean Technologies
      PubDate: 2021-01-26
      DOI: 10.3390/cleantechnol3010005
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 81-97: Social and Technological Impact of
           Businesses Surrounding Electric Vehicles

    • Authors: Rachana Vidhi, Prasanna Shrivastava, Abhishek Parikh
      First page: 81
      Abstract: Electric vehicle (EV) penetration has been increasing globally and is expected to continue its exponential growth over the coming decades. Several countries have already announced plans to achieve total or partial electrification of their vehicle fleets. Such rapid transportation electrification will have a significant impact on society and businesses that support the transportation industry. Additionally, new business opportunities will be available to support this technological evolution. In this paper, the business opportunities emerging from EVs and their supporting infrastructure are reviewed. It has been observed that several businesses, such as sustainable mining and manufacturing, will need to be developed before EV growth as they provide the initial platform required for EV adoption. Other businesses such as fleet optimization, battery management, and recycling can be developed at a later stage. All of these businesses will also have social and technological impacts, which will drive policy decisions. Regional governments play a critical role in ensuring the smooth execution of a transition to transportation electrification through social programs, such as training and education for equitable growth, and legislative decisions, such as technology standardization.
      Citation: Clean Technologies
      PubDate: 2021-02-01
      DOI: 10.3390/cleantechnol3010006
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 98-122: Review of Methods for Assessing the
           Impact of WWTPs on the Natural Environment

    • Authors: Joanna Bąk, Krzysztof Barbusiński, Maciej Thomas
      First page: 98
      Abstract: Environmental management in facilities such as wastewater treatment plants (WWTPs) allows for the implementation of the Deming cycle, and thus the constant improvement of the mitigation of the environmental impact. The correct diagnosis of the current state of functioning of the WWTPs, the identification of aspects that may have a measurable impact on the environment, and their assessment are of key importance. The article discusses the possible causes of the impact of WWTPs on the natural environment. Among other problems, such issues as energy consumption, noise and the formation of bioaerosols and odor nuisances were taken into account. Different ways of assessing the impact of wastewater treatment plants on the environment were collated, taking into account the need to assess not only the technological process itself but also the buildings during their use. The results of methods for assessing the environmental impact of wastewater treatment plants in selected countries were also compared.
      Citation: Clean Technologies
      PubDate: 2021-02-01
      DOI: 10.3390/cleantechnol3010007
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 123-137: Comparison of Different References
           When Assessing PV HC in Distribution Networks

    • Authors: Samar Fatima, Verner Püvi, Matti Lehtonen
      First page: 123
      Abstract: The burgeoning photovoltaics’ (PVs) penetration in the low voltage distribution networks can cause operational bottlenecks if the PV integration exceeds the threshold known as hosting capacity (HC). There has been no common consensus on defining HC, and its numerical value varies depending on the reference used. Therefore, this article compared the HC values of three types of networks in rural, suburban, and urban regions for different HC reference definitions. The comparison was made under balanced and unbalanced PV deployment scenarios and also for two different network loading conditions. A Monte Carlo (MC) simulation approach was utilized to consider the intermittency of PV power and varying loading conditions. The stochastic analysis of the networks was implemented by carrying out a large number of simulation scenarios, which led towards the determination of the maximum amount of PV generation in each network case.
      Citation: Clean Technologies
      PubDate: 2021-02-01
      DOI: 10.3390/cleantechnol3010008
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 138-155: Removal of Odors (Mainly H2S and
           NH3) Using Biological Treatment Methods

    • Authors: Krzysztof Barbusiński, Anita Parzentna-Gabor, Damian Kasperczyk
      First page: 138
      Abstract: This study reviews the available and most commonly used methods of gas deodorization. Comparing various methods of odor removal, undoubtedly biological methods of pollution degradation have an advantage over others—chemical and physical. This advantage is manifestedmainly in ecological and economic terms. The possibility of using biological methods to remove H2S and NH3, as the most common emitted by the municipal sector companies, was analyzed in terms of their removal efficiency. The method of bio-purification of air in biotrickling filters is more advantageous than the others, due to the high effectiveness of VOCs and odors degradation, lack of secondary pollutants, and economic aspects—it is a method competitive to the commonly used air purification method in biofilters.
      Citation: Clean Technologies
      PubDate: 2021-02-17
      DOI: 10.3390/cleantechnol3010009
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 156-182: Bio-Hydrogen Production from
           Wastewater: A Comparative Study of Low Energy Intensive Production

    • Authors: A K M Khabirul Islam, Patrick S. M. Dunlop, Neil J. Hewitt, Rose Lenihan, Caterina Brandoni
      First page: 156
      Abstract: Billions of litres of wastewater are produced daily from domestic and industrial areas, and whilst wastewater is often perceived as a problem, it has the potential to be viewed as a rich source for resources and energy. Wastewater contains between four and five times more energy than is required to treat it, and is a potential source of bio-hydrogen—a clean energy vector, a feedstock chemical and a fuel, widely recognised to have a role in the decarbonisation of the future energy system. This paper investigates sustainable, low-energy intensive routes for hydrogen production from wastewater, critically analysing five technologies, namely photo-fermentation, dark fermentation, photocatalysis, microbial photo electrochemical processes and microbial electrolysis cells (MECs). The paper compares key parameters influencing H2 production yield, such as pH, temperature and reactor design, summarises the state of the art in each area, and highlights the scale-up technical challenges. In addition to H2 production, these processes can be used for partial wastewater remediation, providing at least 45% reduction in chemical oxygen demand (COD), and are suitable for integration into existing wastewater treatment plants. Key advancements in lab-based research are included, highlighting the potential for each technology to contribute to the development of clean energy. Whilst there have been efforts to scale dark fermentation, electro and photo chemical technologies are still at the early stages of development (Technology Readiness Levels below 4); therefore, pilot plants and demonstrators sited at wastewater treatment facilities are needed to assess commercial viability. As such, a multidisciplinary approach is needed to overcome the current barriers to implementation, integrating expertise in engineering, chemistry and microbiology with the commercial experience of both water and energy sectors. The review concludes by highlighting MECs as a promising technology, due to excellent system modularity, good hydrogen yield (3.6–7.9 L/L/d from synthetic wastewater) and the potential to remove up to 80% COD from influent streams.
      Citation: Clean Technologies
      PubDate: 2021-02-18
      DOI: 10.3390/cleantechnol3010010
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 183-205: Possible Perception Bias in the
           Thermal Evaluation of Evaporation Cooling with a Misting Fan

    • Authors: Craig Farnham, Jihui Yuan
      First page: 183
      Abstract: Mist evaporation cooling (MEC) is increasingly used as a low-energy means to improve thermal comfort in hot environments. However, the thermal sensation votes (TSV) often overshoot values of Predicted Mean Vote (PMV) models. Evaluations of MEC may be affected by an expectation that mist feels cool or the “good subject” effect. Here, subjects are exposed to a misting fan and an identical fan without mist and asked which fan feels cooler. Unknown to the subjects, the misting fan has almost no cooling effect (about 0.4 K reduction in air temperature) and a hidden heater increased the temperature of the misting fan air flow, making it up to 1.6 K warmer than the fan without mist. Supplemental experiments told the subjects about the heater. Surveys of over 300 subjects when varying this misted air temperature showed a bias above random chance that people vote that a misting fan airflow was cooler, even when it was the same temperature or slightly warmer than the non-misting fan. It is possible that the expectation of cooling or good subject effect influences evaluations of mist. This effect should be considered in thermal comfort evaluations of mist cooling and in the deployment of MEC systems.
      Citation: Clean Technologies
      PubDate: 2021-03-01
      DOI: 10.3390/cleantechnol3010011
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 206-226: Kalman Filter-Based Real-Time
           Implementable Optimization of the Fuel Efficiency of Solid Oxide Fuel

    • Authors: Andreas Rauh
      First page: 206
      Abstract: The electric power characteristic of solid oxide fuel cells (SOFCs) depends on numerous influencing factors. These are the mass flow of supplied hydrogen, the temperature distribution in the interior of the fuel cell stack, the temperatures of the supplied reaction media at the anode and cathode, and—most importantly—the electric current. Describing all of these dependencies by means of analytic system models is almost impossible. Therefore, it is reasonable to identify these dependencies by means of stochastic filter techniques. One possible option is the use of Kalman filters to find locally valid approximations of the power characteristics. These can then be employed for numerous online purposes of dynamically operated fuel cells such as maximum power point tracking or the maximization of the fuel efficiency. In the latter case, it has to be ensured that the fuel cell operation is restricted to the regime of Ohmic polarization. This aspect is crucial to avoid fuel starvation phenomena which may not only lead to an inefficient system operation but also to accelerated degradation. In this paper, a Kalman filter-based, real-time implementable optimization of the fuel efficiency is proposed for SOFCs which accounts for the aforementioned feasibility constraints. Essentially, the proposed strategy consists of two phases. First, the parameters of an approximation of the electric power characteristic are estimated. The measurable arguments of this function are the hydrogen mass flow and the electric stack current. In a second stage, these inputs are optimized so that a desired stack power is attained in an optimal way. Simulation results are presented which show the robustness of the proposed technique against inaccuracies in the a-priori knowledge about the power characteristics. For a numerical validation, three different models of the electric power characteristic are considered: (i) a static neural network input/output model, (ii) a first-order dynamic system representation and (iii) the combination of a static neural network model with a low-order fractional differential equation model representing transient phases during changes between different electric operating points.
      Citation: Clean Technologies
      PubDate: 2021-03-01
      DOI: 10.3390/cleantechnol3010012
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 227-242: Reducing the Structural Mass of
           Large Direct Drive Wind Turbine Generators through Triply Periodic Minimal
           Surfaces Enabled by Hybrid Additive Manufacturing

    • Authors: Austin C. Hayes, Gregory L. Whiting
      First page: 227
      Abstract: As the power output of direct drive generators increases, they become prohibitively large with much of this material structural support. In this work, implicit modeling was coupled to finite element analysis through a genetic algorithm variant to automate lattice optimization for the rotor of a 5 MW permanent magnet direct drive generator for mass reduction. Three triply periodic minimal surfaces (TPMS) were chosen: Diamond, Schwartz Primitive, and Gyroid. Parameter and functionally graded lattice optimization were employed to reduce mass within deflection criteria. Inactive mass for the 5 MW Diamond, Schwartz Primitive, and Gyroid optimized designs was 10,043, 10,858, and 10,990 kg, respectively. The Schwartz Primitive rotor resulted in a 34% reduction in inactive mass compared to a 5 MW baseline design. Radial and axial deflections were below the critical limit of 0.65 and 32.17 mm, respectively. The lowest torsional deflection was seen in the Schwartz Primitive TPMS lattice at 3.89 mm. Based on these designs, hybrid additive manufacturing with investment casting was used to validate manufacturability in metal. A fused deposition modeling (FDM) TPMS topology was printed for validation of the FEA results. Comparison between digital image correlation of the FDM printed design and FEA design resulted in a 6.7% deformation difference for equivalent loading conditions.
      Citation: Clean Technologies
      PubDate: 2021-03-01
      DOI: 10.3390/cleantechnol3010013
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 243-259: Renewable Biomass Utilization: A
           Way Forward to Establish Sustainable Chemical and Processing Industries

    • Authors: Yadhu N. Guragain, Praveen V. Vadlani
      First page: 243
      Abstract: Lignocellulosic biomass feedstocks are promising alternatives to fossil fuels for meeting raw material needs of processing industries and helping transit from a linear to a circular economy and thereby meet the global sustainability criteria. The sugar platform route in the biochemical conversion process is one of the promising and extensively studied methods, which consists of four major conversion steps: pretreatment, hydrolysis, fermentation, and product purification. Each of these conversion steps has multiple challenges. Among them, the challenges associated with the pretreatment are the most significant for the overall process because this is the most expensive step in the sugar platform route and it significantly affects the efficiency of all subsequent steps on the sustainable valorization of each biomass component. However, the development of a universal pretreatment method to cater to all types of feedstock is nearly impossible due to the substantial variations in compositions and structures of biopolymers among these feedstocks. In this review, we have discussed some promising pretreatment methods, their processing and chemicals requirements, and the effect of biomass composition on deconstruction efficiencies. In addition, the global biomass resources availability and process intensification ideas for the lignocellulosic-based chemical industry have been discussed from a circularity and sustainability standpoint.
      Citation: Clean Technologies
      PubDate: 2021-03-17
      DOI: 10.3390/cleantechnol3010014
      Issue No: Vol. 3, No. 1 (2021)
  • Clean Technol., Vol. 3, Pages 260-287: Multiphysics Design of Pet-Coke

    • Authors: Alon Davidy
      First page: 260
      Abstract: Pet-coke (petroleum coke) is identified as a carbon-rich and black-colored solid. Despite the environmental risks posed by the exploitation of pet-coke, it is mostly applied as a boiling and combusting fuel in power generation, and cement production plants. It is considered as a promising replacement for coal power plants because of its higher heating value, carbon content, and low ash. A computational fluid dynamics (CFD) computational model of methane steam reforming was developed in this research. The hydrogen production system is composed from a pet-coke burner and a catalyst bed reactor. The heat released, produced by the pet-coke combustion, was utilized for convective and radiative heating of the catalyst bed for maintaining the steam reforming reaction of methane into hydrogen and carbon monoxide. This computational algorithm is composed of three steps—simulation of pet-coke combustion by using fire dynamics simulator (FDS) software coupled with thermal structural analysis of the burner lining and a multiphysics computation of the methane steam reforming (MSR) process taking place inside the catalyst bed. The structural analysis of the burner lining was carried out by coupling the solutions of heat conduction equation, Darcy porous media steam flow equation, and structural mechanics equation. In order to validate the gaseous temperature and carbon monoxide mole fraction obtained by FDS calculation, a comparison was carried out with the literature results. The maximal temperature obtained from the combustion simulation was about 1440 °C. The calculated temperature is similar to the temperature reported, which is also close to 1400 °C. The maximal carbon dioxide mole fraction reading was 15.0%. COMSOL multi-physics software solves simultaneously the catalyst media fluid flow, heat, and mass with chemical reaction kinetics transport equations of the methane steam reforming catalyst bed reactor. The methane conversion is about 27%. The steam and the methane decay along the catalyst bed reactor at the same slope. Similar values have been reported in the literature for MSR temperature of 510 °C. The hydrogen mass fraction was increased by 98.4%.
      Citation: Clean Technologies
      PubDate: 2021-03-17
      DOI: 10.3390/cleantechnol3010015
      Issue No: Vol. 3, No. 1 (2021)
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