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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]

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]