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A novel solar PV and wind energy based system is proposed in this study for capturing carbon dioxide as well as producing hydrogen, urea and power. Both Aspen Plus and EES software packages are employed for analyses and simulations. The present system is designed in a way that PEM electrolyzer is powered by the wind turbines for hydrogen production, which is further converted into ammonia and then synthesizes urea by capturing CO 2 and additional power is supplied to the community. The solar PV is employed to power the cryogenic air separation unit and the additional power is used for the industrial purpose. In the proposed system, ammonia does not only capture CO 2 but also synthesizes urea for fertilizer industry. The amount of electrical power produced by the system is 2.14 MW. The designed system produces 518.4 kmol/d of hydrogen and synthesizes 86.4 kmol/d of urea. Furthermore, several parametric studies are employed to investigate the system performance. • A novel solar-wind hybrid energy system is developed for hydrogen and urea production. • Produced hydrogen is converted into ammonia and synthesizes urea by capturing CO 2. • The amount of electrical power produced by the system is 2.14 MW. • Designed system produces 518.4 kmol/d of H 2 and synthesizes 86.4 kmol/d of urea. [ABSTRACT FROM AUTHOR]

In this study, a new solar and geothermal based integrated system is developed for multigeneration of electricity, fresh water, hydrogen and cooling. The system also entails a solar integrated ammonia fuel cell subsystem. Furthermore, a reverse osmosis desalination system is used for fresh water production and a proton exchange membrane based hydrogen production system is employed. Moreover, an absorption cooling system is utilized for district cooling via available system waste heat. The system designed is assessed thermodynamically through approaches of energy and exergy analyses. The overall energy efficiency is determined to be 42.3%. Also, the overall exergy efficiency is assessed, and it is found to be 21.3%. The exergy destruction rates in system components are also analysed and the absorption cooling system generator as well as geothermal flash chamber are found to have comparatively higher exergy destruction rates of 2370.2 kW and 643.3 kW, respectively. In addition, the effects of varying system parameters on the system performance are studied through a parametric analyses of the overall system and associated subsystems. • A new solar and geothermal based system is integrated with ammonia fuel cell. • Multigeneration is achieved with electricity, hydrogen, cooling and fresh water. • Overall energy efficiency of the developed system is 42.3%. • Exergy efficiency of overall system is 21.3%. [ABSTRACT FROM AUTHOR]

Herein, a comparative energetic and life‐cycle assessment (LCA) study is performed on coal and natural gas‐based combined heat and power cogeneration plants. Different types of power plants, including gas turbine, steam turbine, and combined‐cycle plants, are considered. Three types of LCA methodologies, including CML 2001, TRACI, and ReCiPe, are used to analyze the life‐cycle environmental impacts of each plant. The coal‐based cogeneration plant is found to entail the comparatively lowest life‐cycle energy efficiency of 43.6%, and the natural gas‐based combined‐cycle cogeneration plant is found to have the highest efficiency of 59.6%. Furthermore, the coal‐based life cycle is also found to entail the highest life‐cycle environmental impacts comparatively. According to CML 2001, it entails a global‐warming potential of 0.229 kg CO2eq MJ−1 and an acidification potential of 7.03E‐4 kg SO2eq MJ−1. The natural gas‐fired boiler‐type cogeneration plant is observed to have a comparatively higher toxicity and eutrophication potential of 2.72E‐4 kg DCBeq MJ−1 and 2.78E‐5 kg PO4eq MJ−1, respectively. The lowest overall life‐cycle environmental impacts comparatively are found to be associated with the natural gas‐based combined‐cycle cogeneration plant. [ABSTRACT FROM AUTHOR]

In the present study, a new ammonia‐based system is developed and investigated as an energy storage option. In this regard, an environmentally benign cyclic synthesis and usage of ammonia is proposed. The proton exchange membrane‐based electrolysis is used for hydrogen generation with cyclic water usage and production. A direct ammonia fuel cell is employed for power generation. The performance of the developed system is investigated through both energetic and exergetic analyses. In addition, different phases of charging and discharging are considered during the energy storage operation. Furthermore, several parametric investigations are conducted to study the effects of changing operating conditions. The energy efficiency of the charging phase is found to be 41.1% and the exergy efficiency is evaluated to be 43.7%. Moreover, the energetic efficiency of the discharging phase is 78.1% while the exergetic efficiency is 73.4%. The overall efficiency of the system considering both charging and discharging phases is evaluated as 32.1%. [ABSTRACT FROM AUTHOR]

Summary: In this study, a novel wind energy‐based carbon dioxide (CO2) capturing system is developed and investigated for practical applications to reduce environmental emissions. The aqueous ammonia‐based capturing technology is utilized. Wind turbines are used to operate the onsite ammonia synthesis as well as hydrogen production. The proton exchange membrane electrolysis system is considered for hydrogen production and the Haber‐Bosch ammonia synthesis technique is utilized. The developed system is modeled in Aspen Plus software. The system performance for CO2 capture is studied through economic, energy, and exergy perspectives. The CO2 capture cost is evaluated to be between 0.1 and 0.23 $/kg CO2. Furthermore, the system CO2 capture rate is determined to be 3.5 kg/s. Moreover, for a unit mass of CO2 captured, the energy consumption is found to be 640.1 kg CO2/MWh. Several parametric studies are also conducted to analyze the effects of varying operating conditions on the system performance. [ABSTRACT FROM AUTHOR]

A new energy system for power, hydrogen and fresh water production is proposed. The environmentally benign ocean thermal energy conversion (OTEC), wind and solar energy resources are utilized. The hybrid thermochemical CuCl cycle is used for hydrogen production, and the reverse osmosis (RO) desalination system is incorporated for producing fresh water. The presently developed system is analyzed through thermodynamic energy and exergy approaches. The energetic efficiency of the integrated trigeneration system is determined to be 45.3%, and the exergetic efficiency is found to be 44.9%. In addition to this, the energy efficiency of the OTEC power generation cycle is 4.5% while the exergy efficiency is found to be 12.9%. Furthermore, the CuCl hydrogen production cycle is examined to have exergetic and energetic efficiencies of 36% and 35.2%, respectively. Also, numerous parametric studies are performed to analyze the system performance at different operating parameters. [ABSTRACT FROM AUTHOR]

In this study, hydrogen production via microwave plasma is investigated, analyzed and simulated in a novel way for practical applications. The water vapor when in proximity of a tungsten electrode is modeled for the generation of hydrogen gas. A numerical simulation study is performed using plasma and electromagnetic wave COMSOL modules to analyze the plasmolysis of water vapor within a vacuum concealed reaction vessel entailing a tungsten electrode. A kinetic model is therefore developed to represent the reaction mechanisms and interactions between the species within the plasmolysis reactor. The dynamic results of electron density, electron temperature, plasma rate, and species interactions are extracted through the kinetic model. Within the time domain of 10−16 to 10−14 s, the hydrogen concentration is found to increase to 4.5815 × 10−11 mol/m3 with a corresponding decrease in water vapor concentration of 1.782 × 10−8 mol/m3, respectively. The dynamic variations in the concentrations of other dissociated species are investigated across the geometry of the reaction domain studied, and it is therefore concluded that the tip of the electrode entails the highest species concentrations. • Modeling of microwave hydrogen production via water vapor in COMSOL Multiphysics. • Plasma and electromagnetic frequency domain COMSOL modules utilized. • Hydrogen concentration of 4.5815 × 10−11 mol/m3 achieved within 10−16 to 10−14 s. • Corresponding water vapor concentration reduces by 1.782 × 10−8 mol/m3. [ABSTRACT FROM AUTHOR]

Summary: In this paper, we develop and experimentally investigate a novel hybrid ammonia fuel cell and thermal energy storage system. A molten alkaline salt is utilized for storing thermal energy as well as operating an alkaline electrolyte‐based direct ammonia fuel cell. The specific thermal energy storage capacity of the hybrid system is found to be 133 kJ kg−1 at a temperature of 320°C. Furthermore, the maximum power densities are found to be 2.1±0.1 W m−2 to 2.3±0.1 W m−2 for operating temperatures varying between 220°C and 320°C. The energy efficiency is evaluated as 20.6±0.6%, and the exergy efficiency is determined to be 23.3±0.7% at the peak power density. [ABSTRACT FROM AUTHOR]

Abstract In the present study, a comparative well to pump life cycle assessment is conducted on the hydrogen production routes of water electrolysis, biomass gasification, coal gasification, steam methane reforming, hydrogen production from ethanol and methanol. The CML 2001 impact assessment methodology is employed for assessment and comparison. Comparatively higher life cycle Carbon dioxide and Sulphur oxide emissions of 27.3 kg/kg H 2 and 50.0 g/kg H 2 respectively are determined for the water electrolysis hydrogen production route via U.S. electricity mix. In addition, the life cycle global warming potential of this route (28.6 kg CO 2eq /kg H 2) is found to be comparatively higher than other routes followed by coal gasification (23.7 kg CO 2eq /kg H 2). However, the ethanol based hydrogen production route is estimated to have comparatively higher life cycle emissions of nitrogen dioxide (19.6 g/kg H 2) and volatile organic compounds (10.3 g/kg H 2). Moreover, this route is determined to have a comparatively higher photochemical ozone creation potential of 0.0045 kg-ethene eq /kg H 2 as well as eutrophication potential of 0.0043 kg PO 4eq /kg H 2. The results of this study are comparatively discussed to signify the importance of life cycle assessment in comparing the environmental sustainability of hydrogen production routes. Highlights • Well to pump life cycle assessment is conducted on various hydrogen production routes. • Water electrolysis via U.S. energy mix estimated with 27.3 kgCO 2 /kgH 2 life cycle emissions. • Global warming potential of coal gasification is estimated as 23.7 kg CO 2eq /kg H 2. • Ethanol based route is found to have life cycle NO x emissions of 19.6 g/kg H 2. [ABSTRACT FROM AUTHOR]

Conventional locomotives employing diesel-based propulsion systems have raised concerns about the environment and hence sustainable development due to their emissions. To obtain an environmentally benign railway system, fuel cell-based locomotives are considered promising candidates owing to their high efficiencies as well as environmental performance. In the present study, a review of the development of fuel cell-based locomotives is conducted and their current progress is described. Further, investigations conducted on various aspects of these types of locomotives are discussed. The literature studies were found to be focused on four main areas namely (1) prototype design/analysis, (2) energy management, (3) feasibility and economic assessment and (4) environmental performance. Fuel cell-based hybrid locomotives entail the potential to reduce the environmental emissions considerably with similar investment costs as diesel fuel-based locomotives. Nearly 3318 tonnes/year of CO2 emissions may be reduced by replacing diesel engine locomotives with fuel cell trains. Approximately 98% of NOx emissions are estimated to be reduced with the utilization of hybrid fuel cell locomotives. Moreover, several control systems utilizing fuzzy logic control strategy have been proved to be efficient energy management aids for such locomotives. Overall locomotive efficiencies of 50.9% are achievable with the deployment of such control strategies that effectively manage the power demands between the fuel cells, batteries and supercapacitors. [ABSTRACT FROM AUTHOR]

Hydrogen is a fuel with immense potential of satisfying the need for environmentally benign energy sources, and waste-derived hydrogen is promising in diverting waste streams away from landfills and other costly treatment. Nonetheless, many waste-to-hydrogen pathways are incipient and require significant efforts to be established as an indispensable element of the path towards sustainability. This review comprehensively evaluates waste-to-hydrogen technologies from technological, economic, environmental, and societal viewpoints. State-of-the-art of five technologies was summarized, focusing on emerging trends in published literature. Several knowledge gaps, future research prospects, and possible improvements related to performance, greenhouse gas emissions, production costs, hydrogen-based transportation, and public acceptance were also identified. Fulfilling the lack of techno-economic and environmental studies of waste-to-hydrogen routes, incorporation of renewable energy into processes, and necessities of scaling-up and production cost reduction are prominent among research needs recognized through this review. Conclusions of this study will be beneficial towards sustainably integrating hydrogen into large-scale energy systems. • Hydrogen production from different types of wastes was critically reviewed. • The state-of-the-art of five waste-to-hydrogen processes was compiled. • Emissions of waste-based hydrogen production are lower than conventional methods. • Thermochemical methods perform better than biochemical methods techno-economically. • Lowered cost and improved safety increase social acceptance of waste-to-hydrogen. [ABSTRACT FROM AUTHOR]