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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]

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]

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]