4E valuation of standalone hybrid renewable energies system for building freshwater and electricity demand using green hydrogen yield and water desalination

Abstract

4E analysis of a designed hydrogen-based standalone system powered by hybrid renewable energy (RE) sources of photovoltaic (PV) panels and wind turbines (WTs) is presented to provide a building with its yearly electricity, freshwater, and hot water. These requirements are satisfied by a new hybrid system composed of proton exchange membrane (PEM) electrolyzers, PEM fuel cells (FCs), reverse osmosis (RO), and humidification dehumidification (HDH). A mathematical model is constructed and solved using MATLAB/Simulink to simulate the entire system under the climate of Alexandria, Egypt. The system optimization demonstrates that the minimum hydrogen storage tank size is 1659.62 kg, achieved at 196 PV panels and 23 WTs, resulting in a PV power ratio of 33.03 %. The recovered FC heat is utilized in HDH to generate 82.53 m³ of freshwater, representing 4.89 % of the total water consumption, while RO supplies the rest. The overall system’s annual energy and exergy efficiencies are 14.09 % and 18.3 %, respectively. The designed system demonstrates its efficacy for meeting residential building demands with a levelized cost of energy (LCOE) of 0.552 US$/kWh based on a total annual cost of 148,243.50 US$ (2,470.73 US$/person) and CO₂ emission savings of 147.61 tons. The sensitivity analysis shows that the system is more sensitive to wind speed changes than solar radiation.