Development of an off-grid electrical vehicle charging station hybridized with renewables including battery cooling system and multiple energy storage units

Electric vehicles expansion is accelerating rapidly due to e-mobility’s massive contribution in reducing fossil fuel consumption and CO₂ emissions. Fulfilling the charging requirements of millions of electrical vehicles from the grid would overload the network and introduce substantial burden on the power sector. This study proposes, and thermodynamically assesses, a grid-independent and renewable energy-based, stand-alone electrical vehicle charging station consisting of CPV/T, wind turbine and biomass combustion-based steam Rankine cycle plant. Hydrogen and ammonia-based fuel cells are integrated in the design along with electrochemical, chemical and thermal storage units to ensure uninterrupted charging services during night times and unfavorable weather conditions. Since the proposed design is suggested for use in the State of Qatar, which is located in a hot region, an absorption cooling system is incorporated to cool the produced NH₃ gas and convert it into liquid phase for optimal storage purposes and to maintain the operating temperature of the battery system within the allowable limits. The thermodynamic analysis followed in this study is based on writing the balance equations for mass, energy, entropy and exergy for the system’s components along with their energy and exergy efficiency equations. The results show that the energy generated from renewable energy sources and fuel cells are sufficient to fast-charge 80 electrical vehicles daily. The energy efficiencies of H₂ fuel cell, NH₃ fuel cell, CPV/T, wind turbine and energetic COP of the absorption cooling system are found to be 77%, 72%, 45%, 43% and 0.72, respectively. The exergy efficiency of CPV/T and the exergetic COP of the absorption cooling system are found to be 37% and 0.19, respectively. The overall energy and exergy efficiencies of the proposed integrated system are found to be 45% and 19%, respectively

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Published in: Energy Reports
License: http://creativecommons.org/licenses/by/4.0/
See article on publisher's website: https://dx.doi.org/10.1016/j.egyr.2020.07.022