Optimized system for combined production of electricity/green hydrogen for multiple energy pathways: a case study of Egypt

By optimal sizing of a wind/photovoltaic hybrid renewable-energy (RE) system, trimming the surplus capacity to reduce the fluctuations in the electricity supplied to the grid, and using it to produce green hydrogen through electrolysis, a stable output with maximum possible capacity factor (CF) is generated to maintain the electricity grid stability. Simultaneously, the trimmed energy is used in a secondary conversion path that minimizes the weighted average cost of the energy generated from the entire plant. This surplus power-to-gas conversion allows the use of green hydrogen to produce electricity, methanol, or ammonia subject to the resource availability, site characteristics, and financial feasibility. Based on robust site selection criteria, the best performance is obtained at two sites: Ras Ghareb and Minya, achieving the lowest energy cost with some variance in their performance. For the Ras Ghareb site, the optimally sized RE plant provided the grid with a quasi-steady capacity of 423 MW with a CF of 80.04% and was capable of injecting 2965.8648 GWh throughout the year with the lowest cost of 2.4355 cent/kWh. A surplus of 3.9% of the total energy produced from the plant was directed to produce 1922-ton H2/year, achieving the lowest cost of hydrogen production of $1.9745/kg H2. For the other selected site, Minya, the clipped energy is used to produce 3330.47-ton H2/year with an optimized lowest cost of $3.5268/kg H2. The difference in hydrogen costs was attributed to the number of full operating hours of the electrolyser in both sites. The cost is mainly affected by the electricity price and the electrolyser cost. With both tending to decrease, future forecasts show hydrogen cost reductions. The study models a power-to-X system in which solar and wind energy are combined, and surplus capacity is used to produce green hydrogen through electrolysis. The combined capacity factor and the Pearson correlation coefficient are used as criteria for site screening. Graphical Abstract