A Comprehensive Assessment of an Autonomous Electric Vehicle Fast Charging Station with Multiple Renewables and Energy Storage Systems
Creators: name: Al Wahedi, Abdulla M.
Publisher: name: Manara - Qatar Research Repository
Year: 2024
Subjects: classificationCode: 40
subject: Engineering

description: E-mobility has become of great interest for many countries worldwide, where the main objective is to decrease the dependency on fossil fuel-based transportation means and reduce CO<sub>2</sub> emissions generated from the transportation sector. However, fulfilling the rapidly accelerating charging requirements of electric vehicles (EVs) from the electricity network would: (i) Expand the demand on electricity production, primarily dependent on fossil fuels, (ii) Overload the grid, and (iii) Introduce technical, environmental and economic burden on the power sector. Since the main objective of expanding EV deployment is to reduce the dependency on carbon-based fuels, renewable energy-based systems must be considered to produce the additional required electricity to meet the extra demand.This study proposes a systematic approach to investigate the optimal portfolio of renewable energy sources integrated with multiple energy storage methods to secure power supply for a grid-independent and uninterruptable fast EV charging station. A multigeneration system with multiple useful correlated intermediate outputs is considered while developing the design to increase the overall system efficiency and improve the overall technical and economic performance with reduced environmental effects and associated risks. Based on site-specific conditions of the state of Qatar, the study evaluates different electricity generation sources, energy storage alternatives, energy management scenarios, and multiple risk factors for the decision-making process while developing EV charging infrastructure. Battery performance degradation due to hot temperature issues is tackled by incorporating concentrated photovoltaic thermal (CPVT) in the design to utilize the generated thermal energy in integrating a Li-Br absorption cooling system to sustain the battery temperature within the allowable operation limits. The same cooling system is used to liquefy the NH<sub>3</sub>.Multiple optimization tools and methods inclusive of PVSyst, EES, Visual Basic, and HOMER PRO software are used to conclude that a 60 m hub height wind turbine, 450 kWp concentrated PV system, 500 kW electrolyzer, 100 kW H<sub>2</sub> and NH<sub>3</sub> FCs, 15 kW bio-generator, 200 kg chemical storage tank, 323 - 767 kW Li-ion battery storage, and 299 – 335 kW converter combination is the optimal configuration to produce the needed power to fast-charge 50 - 80 EVs daily. The overall system energy and exergy efficiencies are found as 45% and 19%, respectively. The 880 kWh ideal surplus energy generated from renewable energy sources is dedicated for daily H<sub>2</sub> and NH<sub>3</sub> production to integrate a chemical storage system. The extra energy produced for EV charging from H<sub>2 </sub>and NH3 fuel cells (FCs) assisted in reducing the charging and discharging cycles of the battery storage by 38%, consequently extending its lifetime. The design produces 0.115 - 0.158 tons of CO<sub>2</sub> emissions annually compared to 418.381 tons of CO<sub>2</sub> emissions produced annually from grid-connected EV charging stations considering natural gas is Qatar's sole grid electricity generation source. The overall system's levelized cost of energy (LCOE) ranges between 0.28 - 0.32 $/kWh, and the net present cost (NPC) ranges between $2.53M - $2.92M.A systematic risk-based approach compromising multiple phases and qualitative and quantitative risk assessment techniques are applied to identify the causes and consequences of potentially critical events associated with the design incorporated subsystems and components. Appropriate preventive and protective measures are used to lessen the high-risk levels to acceptable limits. Although the scope of this research is to propose a comprehensive techno-economic and environmental assessment methodology to assist in planning and designing an optimized EV charging infrastructure for the State of Qatar, it is applicable globally where the site-specific conditions data for the country under study shall be considered to obtain the desired results.