Hydrogen production via using excess electric energy of an off-grid hybrid solar/wind system based on a novel performance indicator

The present study aims to assess the potential of renewable energy resources in the Kingdom of Saudi Arabia (KSA) for electricity and hydrogen production. A hybrid renewable energy system which comprises of solar photovoltaic panels, wind turbine, batteries, electrolyzer, and a hydrogen-tank, is considered to meet the electrical requirements of a typical residential house in Dhahran city, eastern province, KSA, while providing the hydrogen fuel to a hydrogen driven vehicle. To determine the effective configuration of the hybrid renewable energy system, a computer code is developed and used for hourly based simulations incorporating real weather data and electric demand. The influence of the hydrogen vehicle refueling profile is investigated and optimization study is performed to minimize levelized cost of electricity (LCOE) and levelized cost of hydrogen while achieving specified relatability limits. To assess the performance of the hydrogen production sub-system, novel performance indicators are introduced, which include: deficiency in hydrogen supply, and loss of hydrogen supply probability (LHSP). The results showed that the electricity demand is fully covered when the optimum configuration of the hybrid system comprised 18 kW PV, 2 wind turbines and 14 batteries with LCOE of 0.593 $/kWh. Hydrogen production and hydrogen storage tank are sized based on the hybrid system excess energy generated after satisfying the electrical load for various hydrogen vehicle refueling scenarios. In this case, daily refueling scenario leads to the minimum possible hydrogen cost of 36.32 $/kg, and zero level of LHSP with 14 kg hydrogen storage. The environmental analysis shows that the developed system contributed in reduction of CO2 emission by 9.66 Tons per year.