Authors:Thanh Binh Nguyen First page: 234 Abstract: Elemental sulfur (S8) was found to react very rapidly (<1 min) with a stoichiometric amount of triphenylphosphine at rt in sufficient amount of solvent (0.2–0.5 mL of solvent/1 mmol of PPh3). Compared to the previously described methods, the present procedure constitute excellent access to triphenylphosphine sulfide. Citation: Clean Technologies PubDate: 2022-03-22 DOI: 10.3390/cleantechnol4020013 Issue No:Vol. 4, No. 2 (2022)
Authors:Anja Pfennig, Axel Kranzmann First page: 239 Abstract: To mitigate carbon dioxide emissions CO2 is compressed and sequestrated into deep geological layers (Carbon Capture and Storage CCS). The corrosion of injection pipe steels is induced when the metal is in contact with CO2 and at the same time the geological saline formation water. Stainless steels X35CrMo17 and X5CrNiCuNb16-4 with approximately 17% Cr show potential as injection pipes to engineer the Northern German Basin geological onshore CCS-site. Static laboratory experiments (T = 60 °C, p = 100 bar, 700–8000 h exposure time, aquifer water, CO2-flow rate of 9 L/h) were conducted to evaluate corrosion kinetics. The anomalous surface corrosion phenomena were found to be independent of heat treatment prior to exposure. The corrosion process is described as a function of the atmosphere and diffusion process of ionic species to explain the precipitation mechanism and better estimate the reliability of these particular steels in a downhole CCS environment. Citation: Clean Technologies PubDate: 2022-03-24 DOI: 10.3390/cleantechnol4020014 Issue No:Vol. 4, No. 2 (2022)
Authors:Thomas Deschamps, Mohamed Kanniche, Laurent Grandjean, Olivier Authier First page: 258 Abstract: The paper evaluates the performance of an adsorption-based technology for CO2 capture directly from the air at the industrial scale. The approach is based on detailed mass and energy balance dynamic modeling of the vacuum temperature swing adsorption (VTSA) process in Aspen Adsorption software. The first step of the approach aims to validate the modeling thanks to published experimental data for a lab-scale bed module in terms of mass transfer and energy performance on a packed bed using amine-functionalized material. A parametric study on the main operating conditions, i.e., air velocity, air relative moisture, air temperature, and CO2 capture rate, is undertaken to assess the global performance and energy consumption. A method of up-scaling the lab-scale bed module to industrial module is exposed and mass transfer and energy performances of the industrial module are provided. The scale up from lab scale to the industrial size is conservative in terms of thermal energy consumption while the electrical consumption is very sensitive to the bed design. Further study related to the engineering solutions available to reach high global gas velocity are required. This could be offered by monolith-shape adsorbents. Citation: Clean Technologies PubDate: 2022-04-08 DOI: 10.3390/cleantechnol4020015 Issue No:Vol. 4, No. 2 (2022)
Authors:Maria João Pereira, Oceane Grosjean, Manuela Pintado, Carla Brazinha, João Crespo First page: 276 Abstract: The increase in environmental consciousness and stricter regulations has motivated industries to seek sustainable technologies that allow valorising wastewaters, contributing to the profitability of overall processes. Canning industry effluents, namely sardine cooking wastewater, have a high organic matter load, containing proteins and lipids. Their untreated discharge has a negative environmental impact and an economic cost. This work aims to design an integrated process that creates value with the costly sardine cooking wastewater effluent. The research strategy followed evaluates coagulation/flocculation technologies as pre-treatment of the sardine cooking wastewater followed by reverse osmosis. Two different added-value products were obtained: a solid fraction rich in proteins, lipids (above 20%), and aromas that might be used for feed/pet/aquaculture applications and, from the processing of the resultant aqueous stream by reverse osmosis, a natural flavouring additive, which can be applied in food/feed. Additionally, the permeate from reverse osmosis presents a much lower organic load than the original raw material, which may be reused in the overall process (e.g., as water for washings) or discharged at a lower cost, with environmental benefits and economic savings. Citation: Clean Technologies PubDate: 2022-04-15 DOI: 10.3390/cleantechnol4020016 Issue No:Vol. 4, No. 2 (2022)
Authors:Maritha Hörsing, Henrik Rasmus Andersen, Roman Grabic, Jes la Cour Jansen, Anna Ledin First page: 296 Abstract: In this study, sorption distribution coefficients were determined for 71 pharmaceuticals, aiming to describe their sorption behavior to powder activated carbon (PAC). The data are expected to be applied when designing and upgrading wastewater treatment plants (WWTP) for improved removal of pharmaceuticals by applying sorption to PAC as an additional removal technique. Sorption isotherms were determined for the pharmaceuticals over a concentration interval covering a wide range from 0.08 to 10 µg/L using PAC at a concentration of 10 mg/L. The best fitted sorption isotherms were used to calculate the distribution coefficients (Kd) and these were applied to estimate that the PAC doses needed to achieve a target concentration of 10 ng/L in the effluent. A target concentration was used since neither discharge limit values nor environmental quality standards in general have been defined for these compounds. Using a %-removal approach does not guarantee achievement of concentrations low enough to protect the water ecosystems. Some of the pharmaceuticals will be reduced by the addition of small amounts of PAC. Examples are atenolol, carbamazepine, citalopram, codeine, fluoxetine and ibuprofen. For others, e.g., oxazepam, an alternative treatment has to be considered since the requested dose is too high to be realistic for a target concentration of 10 ng/L. Citation: Clean Technologies PubDate: 2022-04-25 DOI: 10.3390/cleantechnol4020017 Issue No:Vol. 4, No. 2 (2022)
Authors:Jennifer Reeve, Oliver Grasham, Tariq Mahmud, Valerie Dupont First page: 309 Abstract: A techno-economic analysis has been used to evaluate three processes for hydrogen production from advanced steam reforming (SR) of bio-oil, as an alternative route to hydrogen with BECCS: conventional steam reforming (C-SR), C-SR with CO2 capture (C-SR-CCS), and sorption-enhanced chemical looping (SE-CLSR). The impacts of feed molar steam to carbon ratio (S/C), temperature, pressure, the use of hydrodesulphurisation pretreatment, and plant production capacity were examined in an economic evaluation and direct CO2 emissions analysis. Bio-oil C-SR-CC or SE-CLSR may be feasible routes to hydrogen production, with potential to provide negative emissions. SE-CLSR can improve process thermal efficiency compared to C-SR-CCS. At the feed molar steam to carbon ratio (S/C) of 2, the levelised cost of hydrogen (USD 3.8 to 4.6 per kg) and cost of carbon avoided are less than those of a C-SR process with amine-based CCS. However, at higher S/C ratios, SE-CLSR does not have a strong economic advantage, and there is a need to better understand the viability of operating SE-CLSR of bio-oil at high temperatures (>850 °C) with a low S/C ratio (e.g., 2), and whether the SE-CLSR cycle can sustain low carbon deposition levels over a long operating period. Citation: Clean Technologies PubDate: 2022-04-26 DOI: 10.3390/cleantechnol4020018 Issue No:Vol. 4, No. 2 (2022)
Authors:Hamed Basir, Shahab Alaviyoun, Marc A. Rosen First page: 329 Abstract: An experimental thermal survey of a turbocharger was performed in an engine test cell using IR thermography. The emissivity coefficients of housings were specified using a furnace and camera. It was shown that the emissivity of the turbine, compressor, and bearing housings are 0.92, 0.65, and 0.74, respectively. In addition, thermocouples were mounted on the housing to validate the temperature of the thermal camera while running in an engine test cell. To compare the data of the thermocouple with data from the thermal camera, an image was taken from the sensor’s location on the housing. The experimental results show that the temperature prediction of the thermal camera has less than 1 percent error. Steady-state tests at various working points and unsteady tests including warm-up and cool-down were performed. The measurements indicate that the turbine casing’s maximum temperature is 839 °C. Furthermore, a thermal image of the bearing housing shows that the area’s average temperature, which is close to the turbine housing, is 7 °C lower than the area close to the compressor housing. The temperature of the bearing housing near the turbine side should be higher; however, the effect of the water passing through the bearing housing decreases the temperature. Citation: Clean Technologies PubDate: 2022-04-28 DOI: 10.3390/cleantechnol4020019 Issue No:Vol. 4, No. 2 (2022)
Authors:Kevin Kendall First page: 345 Abstract: Green hydrogen has been known in the UK since Robert Boyle described flammable air in 1671. This paper describes how green hydrogen has become a new priority for the UK in 2021, beginning to replace fossil hydrogen production exceeding 1 Mte in 2021 when the British Government started to inject significant funding into green hydrogen sources, though much less than the USA, Germany, Japan and China. Recent progress in the UK was initiated in 2008 when the first UK green hydrogen station opened in Birmingham University, refuelling 5 hydrogen fuel cell battery electric vehicles (HFCBEVs) for the 50 PhD chemical engineering students that arrived in 2009. Only 10 kg/day were required, in contrast to the first large, green ITM power station delivering almost 600 kg/day of green hydrogen that opened in the UK, in Tyseley, in July 2021. The first question asked in this paper is: ‘What do you mean, Green'’. Then, the Clean Air Zone (CAZ) in Birmingham is described, with the key innovations defined. Progress in UK green hydrogen and fuel cell introduction is then recounted. The remarks of Elon Musk about this ‘Fool Cell; Mind bogglingly stupid’ technology are analysed to show that he is incorrect. The immediate deployment of green hydrogen stations around the UK has been planned. Another century may be needed to make green hydrogen dominant across the country, yet we will be on the correct path, once a profitable supply chain is established in 2022. Citation: Clean Technologies PubDate: 2022-04-30 DOI: 10.3390/cleantechnol4020020 Issue No:Vol. 4, No. 2 (2022)
Authors:Spyridon Karytsas, Dimitrios Mendrinos, Theoni I. Oikonomou, Ioannis Choropanitis, Attila Kujbus, Constantine Karytsas First page: 356 Abstract: Geothermal project development entails a number of risks, the most significant of which is the geological risk. The introduction of a risk mitigation scheme (RMS) might enable project developers to shift some of the geological risk to public or private entities. Keeping the above in mind, the objective of this study is to examine the development of an effective and financially feasible geothermal risk mitigation scheme in Greece, i.e., a country with no such scheme available. In this respect, the existing status of the geothermal sector in the country is presented, followed by an evaluation of the financial sustainability of a potential RMS, taking into account different insurance premiums, risk coverages, and project success rates. The results indicate that alternative insurance premium, risk coverage, and success rate requirements would result in different financial preconditions for the foundation either of a public or a private fund. Keeping in mind that in most examined scenarios the initial RMS capital is expended before the end of the ending of the scheme, it is suggested that such a plan can only be initiated by the public sector, which is typical of countries with little-developed geothermal markets. Citation: Clean Technologies PubDate: 2022-05-07 DOI: 10.3390/cleantechnol4020021 Issue No:Vol. 4, No. 2 (2022)
Authors:Clean Technologies Editorial Office Clean Technologies Editorial Office First page: 377 Abstract: Clean Technologies (Clean Technol.) is instituting the Best Paper Awards to recognize outstanding papers published in the journal [...] Citation: Clean Technologies PubDate: 2022-05-10 DOI: 10.3390/cleantechnol4020022 Issue No:Vol. 4, No. 2 (2022)
Authors:Giovanni Gadaleta, Sabino De Gisi, Francesco Todaro, Michele Notarnicola First page: 380 Abstract: The role of Mechanical–Biological Treatment (MBT) is still of the utmost importance in the management of residual Municipal Solid Waste (MSW). These plants can cover a wide range of objectives, combining several types of processes and elements. The aim of this work is to assess and compare, from an environmental point of view, the performance of seven selected MBT plants currently operating in different countries, which represent the main MBT layout and processes. For the scope, a combined Life Cycle Assessment (LCA) and Material Flow Analysis (MFA) approach has been adopted to assess plant-specific efficiencies in materials and energy recovery. Metals recovery was a common and high-efficiency practice in MBT; further recovery of other types of waste was often performed. Each assessed MBT plant achieved environmental benefits: among them, the highest environmental benefit was achieved when the highest amount of waste was recovered (not only with material recycling). Environmental results were strongly affected by the recycling processes and the energy production, with a little contribution from the energy requirement. The impacts achieved by the MBT process were, on average, 14% of the total one. The main condition for a suitable MBT process is a combination of materials recovery for the production of new raw materials, avoiding disposal in landfill, and refuse-derived fuel production for energy recovery. This work can be of help to operators and planners when they are asked to define MBT schemes. Citation: Clean Technologies PubDate: 2022-05-11 DOI: 10.3390/cleantechnol4020023 Issue No:Vol. 4, No. 2 (2022)
Authors:Abdulelah D. Alhamayani, Qiancheng Sun, Kevin P. Hallinan First page: 395 Abstract: The net-zero global carbon target for 2050 needs both expansion of renewable energy and substantive energy consumption reduction. Many of the solutions needed are expensive. Controlling HVAC systems in buildings based upon thermal comfort, not just temperature, uniquely offers a means for deep savings at virtually no cost. In this study, a more accurate means to quantify the savings potential in any building in which smart WiFi thermostats are present is developed. Prior research by Alhamayani et al. leveraging such data for individual residences predicted cooling energy savings in the range from 33 to 47%, but this research was based only upon a singular data-based model of indoor temperature. The present research improves upon this prior research by developing LSTM neural network models for both indoor temperature and humidity. Validation errors are reduced by nearly 22% compared to the prior work. Simulations of thermal comfort control for the residences considered yielded potential savings in the range of 29–43%, dependent upon both solar exposure and insulation characteristics of each residence. This research paves the way for smart Wi-Fi thermostat-enabled thermal comfort control in buildings of all types. Citation: Clean Technologies PubDate: 2022-05-12 DOI: 10.3390/cleantechnol4020024 Issue No:Vol. 4, No. 2 (2022)
Authors:Alice Sorrenti, Santo Fabio Corsino, Francesco Traina, Gaspare Viviani, Michele Torregrossa First page: 407 Abstract: This work reports the results obtained with an innovative configuration of a closed-static solar greenhouse for sludge drying. The novelty of the solar greenhouse configuration consisted in using a forced ventilation system to provide hot air for sludge drying and the utilization of solar irradiation for energy supply. Wet sewage sludge (97% humidity) was successfully dried up to a residual humidity close to 5% after 25 days during wintertime. The increase of the airflow rate supplied under the sludge bed improved the sludge drying rate. Moreover, the fraction of volatile suspended solids decreased from 70% to 41% after 13 days, indicating that air supply promoted the simultaneous stabilization of the sludge as a side-effect to the drying process. Overall, the specific energy consumption per ton of evaporated water was estimated to approximately 450 kWh/t, resulting in about 55% of energy demand lower than a conventional thermal drying system, while using only free solar energy. The achieved high weight reduction of up to 99% implies a noticeable reduction of the excess sludge handling costs, indicating that solar greenhouse drying is a highly interesting opportunity for sludge drying in medium-small sized WWTPs. Citation: Clean Technologies PubDate: 2022-05-12 DOI: 10.3390/cleantechnol4020025 Issue No:Vol. 4, No. 2 (2022)
Authors:Tien Ngo, Leadin S. Khudur, Ibrahim Gbolahan Hakeem, Kalpit Shah, Aravind Surapaneni, Andrew S. Ball First page: 420 Abstract: In this study, the efficacy of biochar to mitigate ammonia stress and improve methane production is investigated. Chicken manure (CM) was subjected to high-solid mesophilic anaerobic digestion (15% total solid content) with wood biochar (BC). Wood biochar was further treated using HNO3 and NaOH to produce acid–alkali-treated wood biochar (TBC), with an improvement in its overall ammonium adsorption capacity and porosity. Three treatments were loaded in triplicate into the digesters, without biochar, with biochar and with acid–alkali-treated biochar and maintained at 37 °C for 110 days. The study found a significant improvement in CH4 formation kinetics via enhanced substrate degradation, leading to CH4 production of 74.7 mL g−1 VS and 70.1 mL g−1 VS by BC and TBC treatments, compared to 39.5 mL g−1 VS by control treatments on the 28th day, respectively. However, only the use of TBC was able to prolong methane production during the semi-inhibition phase. The use of TBC also resulted in the highest removal of total ammonia nitrogen (TAN) of 86.3%. In addition, the treatment with TBC preserved the highest microbial biomass at day 110. The presence of TBC also resulted in an increase in electrical conductivity, possibly promoting DIET-mediated methanogenesis. Overall, the acid–alkali treatment of biochar can be a novel approach to improve biochar’s existing characteristics for its utilisation as an additive in anaerobic digestion. Citation: Clean Technologies PubDate: 2022-05-13 DOI: 10.3390/cleantechnol4020026 Issue No:Vol. 4, No. 2 (2022)
Authors:Dimitrios Mendrinos, Constantine Karytsas, Spyridon Karytsas, Flavio Poletto, Biancamaria Farina, Erika Barison First page: 440 Abstract: This paper presents correlations derived by linear regression analysis of seismic velocities VP and VS and elastic moduli EP and ES with temperature in Los Humeros superhot (SHGS) and Acoculco enhanced (EGS) geothermal systems at depths down to 3 km below the surface and temperatures up to approximately 400 °C. In Los Humeros, the seismic velocity models were derived from the inversion of legacy active seismic survey data acquired in 1998, as well as from passive seismic monitoring and ambient seismic noise interferometry carried out during 2017–2019 by the GEMex consortium. In the Acoculco EGS, ambient seismic noise data were used. Steady-state formation temperatures were re-evaluated during and after the end of the GEMex project using measurements provided as a courtesy of the Federal Electricity Commission of Mexico (CFE). The density data needed for the calculation of elastic moduli were provided by the GEMex consortium, as derived from the inversion of regional and local gravity surveys. The analysis indicated that statistically significant correlations of seismic parameters to temperature exist in the vertical direction, namely exponential in Los Humeros superhot and logarithmic in Acoculco EGS, but no correlation was evident in the horizontal direction. This result suggests an indirect relationship among the considered variables due to interdependence on other parameters, such as pressure and vapor saturation. As the analysis was performed using only data obtained from sensing-at-surface methods, without direct geophysical calibration at depth, a distributed fiber-optic seismic and temperature sensing system at both surface and downhole is proposed for active-source and passive seismic monitoring, and seismic-while-drilling by the drill-bit source is considered for reverse vertical seismic profile (RVSP) recording whenever possible for future high-temperature geothermal applications. Citation: Clean Technologies PubDate: 2022-05-16 DOI: 10.3390/cleantechnol4020027 Issue No:Vol. 4, No. 2 (2022)
Authors:Fernanda M. L. Veloso, Isaline Gravaud, Frédéric A. Mathurin, Sabrine Ben Rhouma First page: 458 Abstract: Few commercial-scale carbon capture and storage (CCS) projects are currently operating in the world, with almost all in the USA and China. Despite a high number of CCS pilot-scale projects achieved in Europe, only two commercial-scale projects are operating today. The goal of this study is to present a case study in France to select a promising location to deploy a notable CCS pilot-scale project based on a multicriteria regional-scale approach. The methodology applied in this case study describes and assesses different aspects involved in CCS technology at the regional scale, and then an evaluation of economic key performance indicators (KPI) of CCS is carried out. The assessment at the regional scale gives an overview of where CCS could be applied, when CCS could be deployed and how to launch CCS considering the needs and concerns of stakeholders in the region. Technical aspects were mapped, such as the location of irreducible CO2 sources and long-lasting emissions and the location of storage resources and existing potential transport infrastructures. We identified the waste-to-energy and chemical sectors as the main CO2 sources in the region. An economic analysis of a hypothetical scenario of CCS deployment was elaborated considering three of the higher emitters in the region. A CCS scenario in the Paris Basin region with a deployment between 2027 and 2050 indicates a low CO2 cost per ton avoided between 43 EUR/t and 70 EUR/t for a cumulated total of 25 Mt and 16 Mt, respectively, of CO2 captured and stored for 26 years, including 7.7 Mt of CO2 from biomass (potential negative emissions). Storage maturity and availability of the resource are the most uncertain parameters of the scenario, although they are the key elements to push investment in capture facilities and transport. Geological storage pilot projects are mandatory to prove storage resource and should be located in strategic locations close to potential CO2 sources in case of confirmation of proven resources. Well-perceived pilot-scale projects are the first step to start engaging in deciding and investing in commercial-scale CCS projects. Citation: Clean Technologies PubDate: 2022-05-18 DOI: 10.3390/cleantechnol4020028 Issue No:Vol. 4, No. 2 (2022)
Authors:Mohammadali Kiehbadroudinezhad, Adel Merabet, Homa Hosseinzadeh-Bandbafha First page: 477 Abstract: Studies have shown that the role of energy storage systems in human life is increasing day by day. Therefore, this research aims to study the latest progress and technologies used to produce energy storage systems. It also discusses and compares the most recent methods used by researchers to model and optimize the size of these tools and evaluates the strengths and weaknesses of each. Investigations have shown that using energy storage systems in hybrid stand-alone power generation systems based on renewable energy increases the reliability of the power generation systems and increases their efficiency. It has also reduced the cost of transmitting the power grid to remote areas. Furthermore, this study showed that advances in energy storage technology in recent years have led to the development and promotion of clean microgrids. In addition, this review paper also addresses energy storage technology issues and proposes practical and applied solutions. Citation: Clean Technologies PubDate: 2022-06-01 DOI: 10.3390/cleantechnol4020029 Issue No:Vol. 4, No. 2 (2022)
Authors:Siavash Iravani, Rajender S. Varma First page: 502 Abstract: Heavy metal removal using genetically engineered organisms (GEOs) offer more cost and energy-efficient, safer, greener, and environmentally-friendly opportunities as opposed to conventional strategies requiring hazardous or toxic chemicals, complex processes, and high pressure/temperature. Additionally, GEOs exhibited superior potentials for biosynthesis of nanoparticles with significant capabilities in bioreduction of heavy metal ions that get accumulated as nanocrystals of various shapes/dimensions. In this context, GEO-aided nanoparticle assembly and the related reaction conditions should be optimized. Such strategies encompassing biosynthesized nanoparticle conforming to the green chemistry precepts help minimize the deployment of toxic precursors and capitalize on the safety and sustainability of the ensuing nanoparticle. Different GEOs with improved uptake and appropriation of heavy metal ions potentials have been examined for bioreduction and biorecovery appliances, but effective implementation to industrial-scale practices is nearly absent. In this perspective, the recent developments in heavy metal removal and nanoparticle biosynthesis using GEOs are deliberated, focusing on important challenges and future directions. Citation: Clean Technologies PubDate: 2022-06-01 DOI: 10.3390/cleantechnol4020030 Issue No:Vol. 4, No. 2 (2022)
Authors:Fereshteh Safarzadeh Markhali, José A. Teixeira, Cristina M. R. Rocha First page: 512 Abstract: This study examined the influence of ohmic heating (OH), compared to the conventional heating (Conven) and Control (solvent) methods, on the extraction of olive mill leaves. The main extraction parameters were: (i) solvent ratio (aqueous ethanol; 40%, 60%, and 80%, v/v), and (ii) extraction temperature; 45 °C, 55 °C, and 75 °C (for OH and Conven), and room temperature (for Control). The selected response variables were extraction yield (%), total phenolic content (TPC), and antioxidant activity (ABTS and DPPH). The ohmic system, compared to Conven and Control, exhibited the greatest effects (p < 0.001) on increasing (i) extraction yield (34.53%) at 75 °C with 80% ethanol, (ii) TPC at 55 °C (42.53, 34.35, 31.63 mg GAE/g extract, with 60%, 40%, and 80% ethanol, respectively), and (iii) antioxidant potency at 75 °C detected by DPPH and ABTS, in the range of 1.21–1.04 mM TE/g, and 0.62–0.48 mM TE/g extract, respectively. Further, there were relatively similar trends in TPC and antioxidant activity (both methods), regardless of solvent ratios, p < 0.001. These findings demonstrate the potential of ohmic heating, as a green processing tool, for efficient extraction (15 min) of olive leaves. To date, no literature has described ohmic application for olive leave extraction. Citation: Clean Technologies PubDate: 2022-06-01 DOI: 10.3390/cleantechnol4020031 Issue No:Vol. 4, No. 2 (2022)
Authors:Amit Kumar Sharma, Pradeepta Kumar Sahoo, Mainak Mukherjee, Alok Patel First page: 529 Abstract: Biodiesel is an emerging alternative fuel that is generally made from edible and non-edible oilseed crops. Jatropha curcus has a high potential for producing biodiesel, which yields 25–35% oil along with 75–65% solid byproduct, generally called a de-oiled cake. The present manuscript deals with the co-digestion of Jatropha de-oiled cake along with cattle dung (1:1 ratio) for biogas production in a floating-type biogas digester. The experimental study was carried out in a modified KVIC biogas plant of 6 cubic meter capacity for 60 days’ retention time under psychrophilic and mesophilic temperature conditions. During all the experiments, the total solid content of the slurry was maintained fixed at 10–12% by mixing 10 kg Jatropha de-oiled cake and 10 kg cattle dung with 80 kg water. The experimental results showed that the average specific biogas production of Jatropha de-oiled cake and cattle dung slurry was observed to be 0.216 m3/kg TS, 0.252 m3/kg VS and 0.287 m3/kg TS, 0.335 m3/kg VS, respectively, under the aforementioned conditions. Moreover, the biogas methane concentration was observed to be 62.33% to 69.16% under mesophilic temperature conditions compared to the psychrophilic temperature conditions, 65.21% to 69.15%, respectively. Furthermore, the average total volatile solids mass removal efficiency of feeding material in the abovementioned process was 7% higher under mesophilic temperature conditions than psychrophilic temperature conditions. Additionally, the results indicated that a total 588.8 kg of input volatile solids produced a total of 7306.56 MJ/m3 and 5177.88 MJ/m3 energy in 60 days under psychrophilic and mesophilic temperature conditions. On the basis of the results, it is concluded that Jatropha de-oiled cake may be a superior solution for improving biogas quality and composition as well as a value-added product, i.e., organic manure. Citation: Clean Technologies PubDate: 2022-06-02 DOI: 10.3390/cleantechnol4020032 Issue No:Vol. 4, No. 2 (2022)
Authors:Jaime Sieres, Ignacio Ortega, Fernando Cerdeira, Estrella Álvarez, José M. Santos First page: 542 Abstract: The seasonal performance of a heat pump indicates its average performance during the heating and/or cooling season, taking into account the different energy demands and their variability over time. Several European and international regulations and policies related with energy efficiency and the reduction of the carbon footprint of energy related products are affecting the heat pump industry. Among them, the ecodesign regulations impose minimum energy efficiency values for heat pumps, efficiencies that are based on the seasonal coefficient of performance. This work is focused on a domestic brine-to-water heat pump for low-temperature applications. The methodology to determine its seasonal coefficient of performance (SCOP) according to the European standard EN 14825 is explained and evaluated based on experimental results. The impact on the SCOP of using some technology options such as fixed or variable speed compressors, and fixed or variable outlet temperature operation is evaluated. Results show that between the lowest and highest efficient option, the SCOP can be improved by 26%. Citation: Clean Technologies PubDate: 2022-06-16 DOI: 10.3390/cleantechnol4020033 Issue No:Vol. 4, No. 2 (2022)
Authors:Mustafa Alaskari, Arwa M. Kadhim, Ammar A. Farhan, Moustafa Al-Damook, Mansour Al Qubeissi First page: 555 Abstract: Artificial roughness applied to a Solar Air Heater (SAH) absorber plate is a popular technique for increasing its total thermal efficiency (ηt−th). In this paper, the influence of geometrical parameters of V-down ribs attached below the corrugated absorbing plate of a SAH on the ηt−th was examined. The impacts of key roughness parameters, including relative pitch p/e (6–12), relative height e/D (0.019–0.043), angles of attack α (30–75°), and Re (1000–20,000), were examined under real weather conditions. The SAH ηt−th roughened by V-down ribs was predicted using an in-house developed conjugate heat-transfer numerical model. The maximum SAH ηt−th was shown to be 78.8% as predicted under the steady-state conditions of Re = 20,000, solar irradiance G = 1000 W/m2, p/e = 8, e/D = 0.043, and α = 60. The result was 15.7% greater efficiency compared to the default smooth surface. Under real weather conditions, the ηt−th of the roughened SAH with single- and double-glass covers were 17.7 and 20.1%, respectively, which were higher than those of the smooth SAH. Citation: Clean Technologies PubDate: 2022-06-16 DOI: 10.3390/cleantechnol4020034 Issue No:Vol. 4, No. 2 (2022)
Authors:Giovanni Gadaleta, Sabino De Gisi, Francesco Todaro, Michele Notarnicola First page: 570 Abstract: To address the problem of fossil-based pollution, bio-plastics have risen in use in a wide range of applications. The current waste management system still has some weakness for bio-plastics waste (BPW) treatment, and quantitative data is lacking. This study combines environmental and economic assessments in order to indicate the most sustainable and suitable BPW management treatment between organic, plastic and mixed wastes. For the scope, the carbon footprint of each scenario was calculated by life cycle assessment (LCA), while the total cost of the waste management system was used as an economic parameter. The economic evaluation revealed that the organic, plastic and mixed waste treatment routes reached a total cost of 120.35, 112.21 and 109.43 EUR, respectively. The LCA results showed that the incomplete degradation of BPW during anaerobic digestion and composting led to the disposal of the compost produced, creating an environmental burden of 324.64 kgCO2-Eq. for the organic waste treatment route, while the mixed and plastic treatment routes obtained a benefit of −87.16 and −89.17 kgCO2-Eq. respectively. This study showed that, although the current amount of BPW does not affect the treatment process of organic, plastic and mixed wastes, it can strongly affect the quality of the output, compromising its further reuse. Therefore, specific improvement of waste treatment should be pursued, particularly with regard to the anaerobic digestion of organic waste, which remains a promising technology for BPW treatment. Citation: Clean Technologies PubDate: 2022-06-16 DOI: 10.3390/cleantechnol4020035 Issue No:Vol. 4, No. 2 (2022)
Authors:Madhu Andela, Ahmmadhussain Shaik, Saicharan Beemagoni, Vishal Kurimilla, Rajagopal Veramalla, Amritha Kodakkal, Surender Reddy Salkuti First page: 1 Abstract: This paper deals with a reduced switch multi-level inverter for the solar photovoltaic system-based 127-level multi-level inverter. The proposed technique uses the minimum number of switches to achieve the maximum steps in staircase AC output voltage when compared to the flying capacitor multi-level inverter, cascaded type multilevel inverter and diode clamped multi-level inverter. The use of a minimum number of switches decreases the cost of the system. To eliminate the switching losses, in this topology a square wave switch is used instead of pulse width modulation. Thereby the total harmonic distortion (THD) and harmonics have been reduced in the pulsating AC output voltage waveform. The performance of 127-level MLI is compared with 15 level, 31-level and 63-level multilevel inverters. The outcomes of the solar photovoltaic system-based 127-level multi-level inverter have been simulated in a MATLAB R2009b environment. Citation: Clean Technologies PubDate: 2022-01-02 DOI: 10.3390/cleantechnol4010001 Issue No:Vol. 4, No. 1 (2022)
Authors:Ali M. H. A. Khajah, Simon P. Philbin First page: 14 Abstract: There continues to be significant attention and investment in wind power generation, which can supply a high percentage of the global demand for renewable energy if harvested efficiently. The research study is based on a techno-economic analysis of the feasibility of implementing wind power generation in Kuwait for 105 MW of electricity generation based on 50 wind turbines, which is a major requirement for clean energy. The study focused on three main areas of analysis and numerical modelling using the RETScreen software tool. The first area involved evaluating the performance and efficacy of generating wind power by collecting, analysing, and modelling data on observed wind levels, wind turbine operation, and wind power generation. The second area comprised an environmental impact report to assess the environmental benefits of implementing wind power. The third area involved economic analysis of installing wind power in Kuwait. The analysis was undertaken to determine the energy recovery time for wind energy and determine the mitigation of global warming and pollution levels, the decrease of toxic emissions, and any cost savings from implementing clean energy systems in Kuwait. Additionally, sensitivity analysis was undertaken to determine the impact of certain variables in the modelling process. The results were used to estimate that the energy price would be $0.053 per kWh for a power generation capacity of 105 MWh based on an initial cost of US $168 million and O&M of $5 million for 214,000 MWh of electricity exported to the grid. Moreover, the wind turbine farm will potentially avoid the emission of approximately 1.8 million t of carbon dioxide per year, thereby saving about $9 million over 20 years spent through installing carbon capture systems for conventional power plants. The wind farm is estimated to have a payback time of 9.1 years. Citation: Clean Technologies PubDate: 2022-01-10 DOI: 10.3390/cleantechnol4010002 Issue No:Vol. 4, No. 1 (2022)
Authors:Rajeev Ravindran, Kwame Donkor, Lalitha Gottumukkala, Abhay Menon, Amita Jacob Guneratnam, Helena McMahon, Sybrandus Koopmans, Johan P. M. Sanders, James Gaffey First page: 35 Abstract: Global warming and climate change are imminent threats to the future of humankind. A shift from the current reliance on fossil fuels to renewable energy is key to mitigating the impacts of climate change. Biological raw materials and residues can play a key role in this transition through technologies such as anaerobic digestion. However, biological raw materials must also meet other existing food, feed and material needs. Green biorefinery is an innovative concept in which green biomass, such as grass, is processed to obtain a variety of protein products, value-added co-products and renewable energy, helping to meet many needs from a single source. In this study, an analysis has been conducted to understand the renewable energy potential of green biorefinery by-products and residues, including grass whey, de-FOS whey and press cake. Using anaerobic digestion, the biogas and biomethane potential of these samples have been analyzed. An analysis of the fertiliser potential of the resulting digestate by-products has also been undertaken. All the feedstocks tested were found to be suitable for biogas production with grass whey, the most suitable candidate with a biogas and biomethane production yield of 895.8 and 544.6 L/kg VS, respectively, followed by de-FOS whey and press cake (597.4/520.3 L/kg VS and 510.7/300.3 L/kg VS, respectively). The results show considerable potential for utilizing biorefinery by-products as a source for renewable energy production, even after several value-added products have been co-produced. Citation: Clean Technologies PubDate: 2022-01-17 DOI: 10.3390/cleantechnol4010003 Issue No:Vol. 4, No. 1 (2022)
Authors:Marta Barón-Yusty, Ginés Benito Martínez-Hernández, María Ros-Chumillas, Laura Navarro-Segura, Antonio López-Gómez First page: 53 Abstract: (1) Background: New clean technologies are needed to reduce the high frying oil waste in the food industry of fried breaded products, together with the obtention of healthier (less fat content) and safer (less microbial growth and acrylamide formation) breaded products; (2) Methods: This study proposes the new technology consisting of incorporation of encapsulated extra virgin olive oil (EVOO) (α-cyclodextrin: EVOO ratio, 1:2.6) in the breadcrumbs (corn breadcrumbs:encapsulated oil ratio, 2:1) for breading chicken nuggets combined with oil-free pre-cooking (baking 150 °C/5 min) and cooking (baking 180 °C/13 min). As controls, a conventional deep-fat frying (180 °C/30 s) and new technology but without encapsulated EVOO were used; (3) Results: Fat content of baked chicken nuggets with the new technology was reduced by 88%, while no sensory differences were scored compared with conventional deep-fat frying. Furthermore, acrylamide formation was reduced by >55% with the new technology. During storage (4 °C) of pre-cooked chicken nuggets of new technology, microbial growth was reduced by 1.4 log units lower compared with deep-fat frying method; (4) Conclusions: the proposed new technology, based on encapsulated EVOO+oil-free pre-cooking/cooking, allows to obtain chicken nuggets that are healthier, safer, and have a longer shelf-life, while frying oil waste is avoided. Citation: Clean Technologies PubDate: 2022-02-02 DOI: 10.3390/cleantechnol4010005 Issue No:Vol. 4, No. 1 (2022)
Authors:Jonathan Paul Marshall First page: 67 Abstract: Carbon capture and storage (CCS) appears to be essential for lowering emissions during the necessary energy transition. However, in Australia, it has not delivered this result, at any useful scale, and this needs explanation. To investigate the reasons for this failure, the paper undertakes a historical and social case study of the Gorgon gas project in Western Australia, which is often declared to be one of the biggest CCS projects in the world. The Gorgon project could be expected to succeed, as it has the backing of government, a practical and economic reason for removing CO2, a history of previous exploration, nearby storage sites, experienced operators and managers, and long-term taxpayer liability for problems. However, it has run late, failed to meet its targets, and not lowered net emissions. The paper explores the social factors which seem to be disrupting the process. These factors include the commercial imperatives of the operation, the lack of incentives, the complexity of the process, the presence of ignored routine problems, geological issues (even in a well-explored area), technical failures, regulatory threats even if minor, tax issues, and the project increasing emissions and consuming carbon budgets despite claims otherwise. The results of this case study suggest that CCS may work in theory, but not well enough under some contemporary forms of social organisation, and the possibilities of CCS cannot be separated from its social background. Social dynamics should be included in CCS projections to enhance the accuracy of expectations. Citation: Clean Technologies PubDate: 2022-02-09 DOI: 10.3390/cleantechnol4010006 Issue No:Vol. 4, No. 1 (2022)
Authors:Krzysztof Barbusiński, Krzysztof Filipek First page: 91 Abstract: Currently, there is a real need for rapid progress and development in almost all industries and areas of human activity [...] Citation: Clean Technologies PubDate: 2022-02-14 DOI: 10.3390/cleantechnol4010007 Issue No:Vol. 4, No. 1 (2022)
Authors:Nahin Tasmin, Shahjadi Hisan Farjana, Md Rashed Hossain, Santu Golder, M. A. Parvez Mahmud First page: 97 Abstract: Industrial manufacturing approaches are associated with processing materials that consume a significant amount of thermal energy, termed as industrial process heat. Industrial sectors consume a substantial amount of energy for process heating over a wide range of temperatures (up to 400 °C) from agriculture, HVAC to power plants. However, the intensive industrial application of fossil fuels causes unfavorable environmental effects that cannot be ignored. To address this issue, green energy sources have manifested their potential as economical and pollution-free energy sources. Nevertheless, the adoption of solar industrial process heating systems is still limited due to a lack of knowledge in the design/installation aspects, reluctance to experience the technical/infrastructural changes, low price of fossil fuels, and lack of relative incentives. For successful solar process heat integration in industries, a proper understanding of the associated design factors is essential. This paper comprehensively reviews the integration strategies of solar industrial process heating systems, appraisal of the integration points, different aspects of solar collectors, installed thermal power, and thermal storage volume covering case studies, reports and reviews. The integration aspects of solar process heat, findings, and obstacles of several projects from the literature are also highlighted. Finally, the integration locations of SHIP systems are compared for different industrial sectors to find out the most used integration point for a certain sector and operation. It was found that for the food, beverage, and agriculture sector, 51% of solar process heat integration occurs at the supply level and 27.3% at the process-level. Citation: Clean Technologies PubDate: 2022-02-17 DOI: 10.3390/cleantechnol4010008 Issue No:Vol. 4, No. 1 (2022)
Authors:Alessandro Arrigoni, Valeria Arosio, Andrea Basso Peressut, Saverio Latorrata, Giovanni Dotelli First page: 132 Abstract: A larger adoption of hydrogen fuel-cell electric vehicles (FCEVs) is typically included in the strategies to decarbonize the transportation sector. This inclusion is supported by life-cycle assessments (LCAs), which show the potential greenhouse gas (GHG) emission benefit of replacing internal combustion engine vehicles with their fuel cell counterpart. However, the literature review performed in this study shows that the effects of durability and performance losses of fuel cells on the life-cycle environmental impact of the vehicle have rarely been assessed. Most of the LCAs assume a constant fuel consumption (ranging from 0.58 to 1.15 kgH2/100 km) for the vehicles throughout their service life, which ranges in the assessments from 120,000 to 225,000 km. In this study, the effect of performance losses on the life-cycle GHG emissions of the vehicles was assessed based on laboratory experiments. Losses have the effect of increasing the life-cycle GHG emissions of the vehicle up to 13%. Moreover, this study attempted for the first time to investigate via laboratory analyses the GHG implications of replacing the hydrophobic polymer for the gas diffusion medium (GDM) of fuel cells to increase their durability. LCA showed that when the service life of the vehicle was fixed at 150,000 km, the GHG emission savings of using an FC with lower performance losses (i.e., FC coated with fluorinated ethylene propylene (FEP) instead of polytetrafluoroethylene (PTFE)) are negligible compared to the overall life-cycle impact of the vehicle. Both the GDM coating and the amount of hydrogen saved account for less than 2% of the GHG emissions arising during vehicle operation. On the other hand, when the service life of the vehicle depends on the operability of the fuel cell, the global warming potential per driven km of the FEP-based FCEV reduces by 7 to 32%. The range of results depends on several variables, such as the GHG emissions from hydrogen production and the initial fuel consumption of the vehicle. Higher GHG savings are expected from an FC vehicle with high consumption of hydrogen produced with fossil fuels. Based on the results, we recommend the inclusion of fuel-cell durability in future LCAs of FCEVs. We also advocate for more research on the real-life performance of fuel cells employing alternative materials. Citation: Clean Technologies PubDate: 2022-02-23 DOI: 10.3390/cleantechnol4010009 Issue No:Vol. 4, No. 1 (2022)
Authors:Hamidreza Nazaripouya First page: 149 Abstract: The increase in the population growth rate and the motivation to overcome issues such as environmental concerns and air pollution have made distributed renewable energy resources (DRER) the most popular option for providing the required energy [...] Citation: Clean Technologies PubDate: 2022-03-01 DOI: 10.3390/cleantechnol4010010 Issue No:Vol. 4, No. 1 (2022)
Authors:Anna Samnioti, Vassiliki Anastasiadou, Vassilis Gaganis First page: 153 Abstract: According to the roadmap toward clean energy, natural gas has been pronounced as the perfect transition fuel. Unlike usual dry gas reservoirs, gas condensates yield liquid which remains trapped in reservoir pores due to high capillarity, leading to the loss of an economically valuable product. To compensate, the gas produced on the surface is stripped from its heavy components and reinjected back to the reservoir as dry gas thus causing revaporization of the trapped condensate. To optimize this gas recycling process compositional reservoir simulation is utilized, which, however, takes very long to complete due to the complexity of the governing differential equations implicated. The calculations determining the prevailing k-values at every grid block and at each time step account for a great part of total CPU time. In this work machine learning (ML) is employed to accelerate thermodynamic calculations by providing the prevailing k-values in a tiny fraction of the time required by conventional methods. Regression tools such as artificial neural networks (ANNs) are trained against k-values that have been obtained beforehand by running sample simulations on small domains. Subsequently, the trained regression tools are embedded in the simulators acting thus as proxy models. The prediction error achieved is shown to be negligible for the needs of a real-world gas condensate reservoir simulation. The CPU time gain is at least one order of magnitude, thus rendering the proposed approach as yet another successful step toward the implementation of ML in the clean energy field. Citation: Clean Technologies PubDate: 2022-03-01 DOI: 10.3390/cleantechnol4010011 Issue No:Vol. 4, No. 1 (2022)
Authors:Carlos C. Duarte, Nuno D. Cortiços First page: 174 Abstract: China promptly took the leading step to mitigate the spread of COVID-19, producing the first scientific guidelines assuming health above energy consumption and significantly changing HVAC/AHU operation. The research intended to fulfill the gap by measuring the impact of the guidelines on energy use intensity, CO2 emissions, and energy operation costs related to workplaces. The guidelines are long-term sector and industry trends following occupants’ health and safety concerns, and today they are applied to nursing homes. The research extended the study to post-COVID-19 scenarios by crossing those settings with published reports on telework predictions. The methodology resorts to Building Energy Simulation software to assess the Chinese standard large office building on 8 climate zones and 17 subzones between pre- and post-COVID-19 scenarios under those guidelines. The outcomes suggest an upward trend in energy use intensity (11.70–12.46%), CO2 emissions (11.13–11.76%), and costs (9.37–9.89%) for buildings located in “warm/mixed” to “subarctic” climates, especially in colder regions with high heating demands. On the other hand, the figures for “very hot” to “hot/warm” climates lower the energy use intensity (14.76–15.47%), CO2 emissions (9%), and costs (9.64–9.77%). Citation: Clean Technologies PubDate: 2022-03-02 DOI: 10.3390/cleantechnol4010012 Issue No:Vol. 4, No. 1 (2022)
Open Access journal
[84 journals]
