Clean Energy Production Technologies Research Articles

Optimization of PEMFC pressure control using fractional PI/D controller with non-integer order: design and experimental evaluation

The fuel-based proton exchange membrane (PEM) fuel cell is a promising technology for clean energy production owing to the several advantages including high efficiency (around 80% theoretical), quiet in operation, and almost zero emission as compared to conventional internal combustion engine. Only hydrogen and oxygen are supplied at the anode and cathode, respectively to generate power and water is produced as by product. However, it suffers to achieve its maximum theoretical efficiency due to lack of flow/pressure management of hydrogen and oxygen in the PEMFC stack which also causes flooding within the cell and reduce the performance of the catalyst and reduces the efficiency. The higher efficiency can be achieved with the proper control of the hydrogen and oxygen inlet flow rate and pressure at the PEMFC. Since it’s crucial to maintaining a consistent supply of exponential pressure, the main focus of this work is pressure regulation at the PEMFC cathode side. A fractional PI/D controller is designed to operate the PEMFC system more realistically. There are three primary objectives of this research work. In the first step, monitoring the PEMFC operating pressure to find out the suitable fractional PI-D controller for a given resilience level, which has the lowest Integration Absolute Error (IAE) to disturbances. The robustness level and/or threshold peak is considered as a tuning parameter for the evaluation. Second, compare the best IAE performance of the fractional PI-D controller with that of simple SIMC rules, where a certain level of resilience is achieved by varying the SIMC tuning variable. Through this comparison, the effectiveness of the recommended controller in achieving the optimal plant performance is evaluated. Thirdly, design a non-integer order PEMFC plant with a fractional controller using MATLAB software and compare the results with existing models. This comparison provides insight into the practical performance of the proposed controller. The results shows that the developed fractional PI/D controller is able to control the pressure very efficiently at the PEMFC cathode side. The findings further emphasise on the important to consider the resilience and robustness levels at the time of developing control systems for PEMFCs. The efficacy of the suggested unique technique is further confirmed by contrasting the suggested controller with the developed models.

Transition Metal Oxides as Hydrogen Evolution Electrocatalyst: Scientometric Analysis

Background:The development of cost-effective and high-activity hydrogen evolution reaction (HER) electrocatalysts is limiting the implementation of hydrogen production from electrochemical and photoelectrochemical water splitting, which is seen as a potential technology for clean energy production and long-term energy storage. Transition metal oxide catalysts, a large class of functional materials with variable elemental compositions and crystal shapes, have piqued the interest of scientists. Now, a scientific-based appraisal of the progress in this scientific field is required, as well as identification of the most promising materials and technologies, as well as present constraints and future commercialization chances.Methods:This article presents a scientometric analysis of transition metal oxides as hydrogen evolution electrocatalysts in the scientific field. 1421 publications from the Web of Science (WoS) database were extracted using a mix of relevant keywords and examined using multiple scientometric indexes utilizing Python and Anaconda Prompt, ScientoPy, and Citespace. It stated that the first point in this subject was in 1992, and that scientific progress has substantially increased since 2015.Results:Articles and reviews account for 83.8 percent and 13.4 percent of all items published in this category, respectively.Conclusion:The top two contributor countries were identified as China and the United States. The most active journal in this field is Journal of Materials Chemistry A.

Hydrogen generation from bamboo biomass using enzymatic hydrolysis and subsequent microbial electrolysis in a single chamber microbial electrolysis cell

Sustainable, economical. and clean energy production technologies acutely needed abundant supply of raw materials (biomass) and superior process engineering techniques to deliver the desired throughput. In this endeavour, here we demonstrated the utilization of lignocellulose (Bambusa bambos) by successive enzymatic treatment and microbial electrolysis in a single chamber MEC for generating clean fuel-hydrogen. In addition, we studied MEC (V=400 mL) by modifying an anode (graphene with 100 cm2 area) with monodisperse iron oxide nanoparticles (IONPs). Enzymatically (10% w/w laccase) pretreated Bambusa bambos with 40.31% reduced lignin was subjected to batch hydrolysis (20% w/w enzyme-to-substrate ratio) using cellulase. The glucose produced (99.54 ± 4 mg/dL) after 96 h of incubation was further operated in single chamber MEC equipped with highly efficient IONPs coated electrodes for hydrogen production. Engineering parameters namely-applied voltage (0.6-1.0 V) and mixing characteristics (0–400 rpm) were also investigated to improve the system performance. The MEC with IONPs coated anode offered hydrogen production efficiency 1.14 times higher as compared to MEC with the uncoated anode. The maximum hydrogen production of 0.02 g (224 mL) per gram of biomass was obtained in MEC with the coated anode at an applied voltage of 0.8 V under the influence of moderate mixing (200 rpm).

Front Cover: CO2 Separation by Imide/Imine Organic Cages (Chem. Eur. J. 49/2022)

CO2 capture and clean energy production technologies are stirring increasing interest due to the visible effects of global warming on our planet. In the background is a picture of a small lake in Lombardy, Italy, as it appeared in 2018. Novel imide/imine cages have shown promising results in the selective separation of CO2 from N2 and CH4 under vacuum swing adsorption conditions. The cages have also been successfully tested as fillers in mixed-matrix membranes. More information can be found in the Research Article by J. C. Jansen, M. Carta, V. Amendola et al. (DOI: 10.1002/chem.202201631).

Assessment of public perception towards the radioactive waste management of Bangladesh

The nuclear power industry is a potential field in the arena of science and technology for clean energy production. Nuclear wastes and radiation are inevitable consequences of nuclear power production, and most people are concerned about it. Bangladesh is going to be the 33rd country to own its first nuclear power plants (NPPs) at Rooppur site in 2023. In this paper, it is shown how people of different ages, genders, and professions react to the safety of radioactive wastes for the development of NPPs. Among 487 participants in the survey, 60% of people believe that radioactive waste generated from NPPs is risky for the environment. In terms of comparison, 40 % of people believe coal power plants are more hazardous to NPPs. On the contrary, 43 % and 50 % of people agreed that radioactive waste disposal would be an unsolved issue and high risk for the country, respectively. However, 34 % and 41 % of respondents partially disagreed with the capability of regulatory authority and the Department of Environment (DoE) on solving the issue, respectively. More importantly, 44 % of people strongly supported the necessity of mass awareness campaigns regarding the safe management of nuclear wastes. The study can be an important tool for the policymakers, regulators, and operators on what action plan needs to be done to increase public acceptance for the safe operation of the nuclear industry.

De-alloyed ternary electrocatalysts with high activity and stability for oxygen reduction reaction

Proton exchange membrane fuel cell is a viable technology for clean energy production, however developing a cost-effective and highly efficient catalyst for oxygen reduction reaction (ORR) is a challenge to overcome. A promising strategy is alloying Pt with transition metals where synergistic effects and strain induced on Pt adatoms can lead to unprecedent activity. Controlling alloy composition and particle structure are highly complex as alloying order increases. Herein, we report a facile and simple one-pot synthesis method, to synthesize carbon-supported PtCuFe nanoparticles surpassing DOE technical requirement of ORR catalyst for PEMFC application. After voltammetric dealloying, a Pt-rich shell is exposed on the surface of the PtCuFe nanoparticles. The elemental composition and electronic environment of PtCuFe nanoparticles are characterized using high-resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The condition of dealloying affects catalytic activity for ORR. Dissolution of non-noble metals exhibits significant improvement of PtCuFe ORR activity, as well as, an enhancement in their stability. D-Pt2CuFe/C-150 catalyst shows an ORR mass activity of 0.99 A mg−1Pt at 0.90 V vs. RHE, records 2.9 fold enhancement over state-of-the-art commercial TKK catalyst. Furthermore, D-Pt1CuFe/C-150 exhibits prolonged stability, with a mass activity loss of only 7.6% after 5000 durability cycles, whereas TKK catalyst suffers for a 29.4% loss under the same conditions.

Efficient removal of tar from gas fraction resulting from thermo-chemical conversion of biomass using coal fly ash–based catalysts

A requirement for the development of a viable biomass conversion technology for clean energy production is the efficient cleaning of the gas fraction. The aim of this work was to use fly ash (AF) to develop cheap and efficient catalysts in removing tar. FA was separated in two fraction, oxide fly ash (OFA) and unburned carbon (UCFA) and both were used for catalysts preparing. The toluene was used as a tar model and a fixed-bed reactor for testing. The calcined oxide fly ash (COFA) showed a steady decrease in catalytic activity, the removal efficiency was reduced by 13.52% after 3 h. Reduced catalyst (RCOFA) and activated and reduced catalyst (AROFA) showed a higher activity than COFA catalyst and were able to maintain their performance. The RCOFA catalytic activity decreased suddenly when the steam was present, and tar removal efficiency descended to 57.32% after only 3 h and to 49.03% after 5hrs, respectively. Results showed that the catalysts obtaining by mixing RCOFA/AROFA with UCFA led to high effective toluene conversion in a reforming environment, over 90% and their catalytic activity remained constant after 12 h, because the unburned carbon presence kept the iron in its reduced form, much more catalytically active.

Detailed microkinetic modelling of syngas to hydrocarbons via Fischer Tropsch synthesis over cobalt catalyst

Fuels production from syngas via Fischer Tropsch synthesis (FTs) is an alternative technology for clean energy production. The microkinetic model is a promising approach for gaining insight into FTs activity. In this study, a systematic microkinetic model was proposed to develop a process for cobalt-catalyzed FTs. All possible elementary reactions based on the carbide mechanism and characteristics of catalyst sites were considered in the kinetic model. The effects of the reaction rate constant, reaction pathways, and H2 to CO ratio were represented by a kinetic parameter, reaction path, and operating parameter, respectively. The model could accurately predict product distribution trends, with an R2 value and mean absolute relative residuals percentage of 0.91–0.93 and 5–43%, respectively, in comparison with experimental data. Hydrogen utilization was predicted and analyzed. High model accuracy was achieved, with a 10−10–10−3% error in the material balance.

Energy recovery from cross-linked polyethylene wastes using pyrolysis and CO2 assisted gasification

High-temperature gasification is an attractive alternative technology for clean energy production from plastic wastes and provides a sustainable pathway for their disposal. Waste cross-linked polyethylene (XLPE) offers good potential energy recovery source because of its high energy density of around 47 MJ/kg that can be converted to syngas using pyrolysis or gasification. CO2 assisted gasification can provide clean and efficient syngas that can be converted further to valuable products. This can effectively decrease the carbon foot-print from the utilization of polyethylene wastes. This paper examines pyrolysis and CO2 assisted gasification of XLPE waste with focus on the kinetics, product yield and syngas yield properties (yield of carbon monoxide, hydrogen, and hydrocarbon) at different temperatures. Pyrolysis experiments were carried out to estimate the impact of the gasifying agent over pyrolysis. Pyrolysis and CO2 assisted gasification were conducted at several temperatures in the range 973 K to 1173 K in steps of 50 K. The results were compared with high-, medium-, low-density polyethylene as well as ultra-high molecular weight polyethylene. Higher temperatures provided increased syngas yields from pyrolysis. The activation energy of pyrolysis from single-step kinetic analysis of TGA data revealed increases with an increase in branching and cross-linking. The reaction profiles of the single step of all the samples (except medium density polyethylene) were found to be closely represented by the Avrami-Erofeev models. Results also revealed that gasification generated more syngas, hydrogen, and energy than pyrolysis. Gasification consumed the CO2 to generate syngas with a mass-specific heating value similar to natural gas suggesting efficient utilization of both CO2 and XLPEs for clean and efficient energy production.

Critical Material Applications and Intensities in Clean Energy Technologies

Clean energy technologies have been developed to address the pressing global issue of climate change; however, the functionality of many of these technologies relies on materials that are considered critical. Critical materials are those that have potential vulnerability to supply disruption. In this paper, critical material intensity data from academic articles, government reports, and industry publications are aggregated and presented in a variety of functional units, which vary based on the application of each technology. The clean energy production technologies of gas turbines, direct drive wind turbines, and three types of solar photovoltaics (silicon, CdTe, and CIGS); the low emission mobility technologies of proton exchange membrane fuel cells, permanent-magnet-containing motors, and both nickel metal hydride and Li-ion batteries; and, the energy-efficient lighting devices (CFL, LFL, and LED bulbs) are analyzed. To further explore the role of critical materials in addressing climate change, emissions savings units are also provided to illustrate the potential for greenhouse gas emission reductions per mass of critical material in each of the clean energy production technologies. Results show the comparisons of material use in clean energy technologies under various performance, economic, and environmental based units.

Well‐Defined Platinum Surfaces for the Ethanol Oxidation Reaction

AbstractDirect ethanol fuel cells are a promising technology for clean energy production. The ethanol oxidation reaction (EOR) is surface sensitive and, hence, the study of single‐crystal electrodes provides fundamental knowledge of the different activity of the metal crystal planes. However, for practical applications, metal nanoparticles dispersed on a porous support are generally used to enhance the efficiency and to reduce the catalyst cost. Although some research has been devoted to the development of shape‐controlled nanoparticles, the finding of an efficient, cost‐effective, and easily scaled‐up catalytic system remains a challenge. Furthermore, the use of a suitable support with a well‐defined nanoarchitecture is essential for the control of the catalyst reactivity. In this Review, a general overview of the performance of single‐crystal electrodes and unsupported/supported shape‐controlled nanoparticles for the EOR is presented, paying special attention to Pt surfaces. Finally, the major challenges and directions for future research are also discussed to guide the design of efficient shape‐controlled catalysts for the EOR.

Transition Metal-Modified Exfoliated Zirconium Phosphate as an Electrocatalyst for the Oxygen Evolution Reaction

Improved electrochemical oxygen evolution catalysis is crucial for many clean-energy production technologies. Recently, transition-metal-modified zirconium phosphate (ZrP) catalysts were studied for the oxygen evolution reaction (OER) in alkaline media. These studies suggest that the OER occurs preferentially on the surface of the layered ZrP nanoparticles rather than the interlayer gallery. Herein, ZrP nanoparticles are exfoliated with tetrabutylammonium hydroxide (TBA+OH–) to further expose surface sites which are subsequently modified with Co and Ni cations by an ion-exchange reaction. Because of the greater surface accessibility of the exfoliated ZrP support, higher loadings of catalyst material were achieved along with improved site access for catalysis. These new composite materials have improved geometric area normalized overpotentials than metal-adsorbed ZrP nanoparticles without exfoliation. Specifically, Co-modified and Ni-modified exfoliated ZrP show a reduction in overpotential at a current de...

Environmental Regulation, Directed Technical Change, and Economic Growth: Theoretic Model and Evidence from China

Can environmental regulation be used to promote directed technical change and economic growth simultaneously? We construct an endogenous economic growth model that includes environmental regulation, the extent of environmental pollution, and economic performance in a general equilibrium framework. We show that in the absence of government intervention, environmental pollution will not automatically disappear as economic growth increases. Furthermore, “threshold constraints” result from “path dependence” in the type of innovation; only when the rate of carbon tax and carbon reduction subsidy reaches a certain extent will individuals (or producers) redirect technical change toward “clean” energy production technologies innovation and away from “dirty” energy production technologies. Our article also discloses the intrinsic principle and micromechanism of environmental regulation to promote economic growth and finds that strict environmental regulation will both significantly promote the evolving labor division in clean energy production technologies innovation and achieve the benefits of improved average labor productivity in the production sector and the market size of goods, so that the benefit exceeds the switching cost.

Nickel-Based Electrocatalysts for Energy-Related Applications: Oxygen Reduction, Oxygen Evolution, and Hydrogen Evolution Reactions

The persistently increasing energy consumption and the low abundance of conventional fuels have raised serious concerns all over the world. Thus, the development of technology for clean-energy production has become the major research priority worldwide. The globalization of advanced energy conversion technologies like rechargeable metal–air batteries, regenerated fuel cells, and water-splitting devices has been majorly benefitted by the development of apposite catalytic materials that can proficiently carry out the pertinent electrochemical processes like oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and water hydrolysis. Despite a handful of superbly performing commercial catalysts, the high cost and low electrochemical stability of precursors have consistently discouraged their long-term viability. As a promising substitute of conventional platinum-, palladium-, iridium-, gold-, silver-, and ruthenium-based catalysts, various transition-metal (TM) i...

Novel photo-reactor for fast screening of photo-catalytic systems

Photo-catalysis is an emerging technology for clean energy production, organic synthesis and environmental protection, etc. While there is a hydrogen of systems and schemes to attain these objectiv ...

Synergetic effects of mixed copper–iron oxides oxygen carriers in chemical looping combustion

Chemical looping combustion (CLC) is an emerging technology for clean energy production from fuels. CLC produces sequestration-ready CO2-streams without a significant energy penalty. Development of efficient oxygen carriers is essential to successfully operate a CLC system. Copper and iron oxides are promising candidates for CLC. Copper oxide possesses high reactivity but it has issues with particle agglomeration due to its low melting point. Even though iron oxide is an inexpensive oxygen carrier it has a slower reactivity. In this study, mixed metal oxide carriers containing iron and copper oxides were evaluated for coal and methane CLC. The components of CuO and Fe2O3 were optimized to obtain good reactivity while maintaining physical and chemical stability during cyclic reactions for methane-CLC and solid-fuel CLC. Compared with single metal oxygen carriers, the optimized Cu–Fe mixed oxide oxygen carriers demonstrated high reaction rate, better combustion conversion, greater oxygen usage and improved physical stability.Thermodynamic calculations, XRD, TGA, flow reactor studies and TPR experiments suggested that there is a strong interaction between CuO and Fe2O3 contributing to a synergistic effect during CLC reactions. The amount of oxygen release of the mixed oxide carrier in the absence of a fuel was similar to that of the single metal oxides. However, in the presence of fuels, the oxygen consumption and the reaction profiles of the mixed oxide carriers were significantly better than that of the single metal oxides. The nature of the fuel not only influenced the reactivity, but also the final reduction status of the oxygen carriers during chemical looping combustion. Cu oxide of the mixed oxide was fully reduced metallic copper with both coal and methane. Fe oxide of the mixed oxide was fully reduced Fe metal with methane but it was reduced to only FeO with coal. Possible mechanisms of how the presence of CuO enhances the reduction of Fe2O3 are discussed.

Enhanced biohydrogen production from tofu residue by acid/base pretreatment and sewage sludge addition

Anaerobic dark fermentation is considered a promising technology for clean energy production and waste reduction. In the present work, tofu residue and sewage sludge were utilized as substrates for fermentative hydrogen production. To increase the biodegradability, tofu residue was pretreated for 30 min in the presence of HCl and NaOH at various concentrations (0, 0.5, 1.0, and 2.0%), and then fermented by a thermophilic (60 °C) mixed culture. The solubility (SCOD/TCOD ratio) of the tofu residue increased from 4 to 30–40% after pretreatment, and the increased soluble constituents were mainly protein rather than carbohydrate compounds. However, in spite of a slight increase of carbohydrate solubility, the H 2 production performance was significantly enhanced by pretreatment, owing to the degradability of thermophilic cultures used on insoluble tofu residues. The limited H 2 yield of 0.30 mol H 2/mol hexose added achieved in the raw tofu residue was increased 1.6- to 4-fold with the highest H 2 yield of 1.25 mol H 2/mol hexose added at 1.0% HCl concentration. Carbohydrate degradation and the H 2 production rate also increased from 39 to 50–65% and 27 to 50–120 mL H 2/L/h, respectively. The role of pretreatment was not only to increase the biodegradability but also to suppress the activity of indigenous non H 2-producers such as lactic acid bacteria and propionic acid bacteria. When sewage sludge was added to acid pretreated (1.0% HCl) tofu residue as a co-substrate, the H 2 yield and H 2 production rate increased to 1.48 mol H 2/mol hexose added and 161 mL H 2/L/h, respectively, which was attributed to the abundant minerals, vitamins, and metals contained in sewage sludge.