Key aspects in quantifying massive solar hydrogen production: Energy intermittence, water availability and electrolyzer technology

This paper reveals the importance of considering restrictions raised by energy and water availability as well as hydrogen production technology in the task of assessing the massive solar hydrogen production in a location. As operation times, maintenance costs, and capital expenditure of electrolysis are key aspects to be considered in the hydrogen production cost, a variety of scenarios depending on the electrolyzer technology were studied. To this end, the case of Mexico was taken as a benchmark due to the availability of the data from up to 8467 automatic weather stations which provided certainty to our estimations. In contrast to previous works, we studied a variety of hydrogen production scenarios depending on the solar harvesting conditions and the hydrogen production process, including the solar and water resource availability, the electrolyzer efficiency, the electricity production cost, and the operation times in accordance to the daylight duration. We found significant differences in the estimation of the hydrogen production using geographic restrictions in the rainfall water, even if 90% of the studied territories that could produce PV energy, used less than 20% of the annual rainfall water to produce hydrogen. Our results revealed that energy production costs, energy availability, and electrolyzer costs are important to assess the final production cost of hydrogen. We found that operation times restricted to sunlight duration were the main factor increasing the production cost of hydrogen, reaching up to 52% of rising; this factor, however, has not been considered by international agencies and institutions to assess the hydrogen production costs. These results reveal that the generation of solar hydrogen may be very expensive in some locations and that production along with other complementary renewable energy sources should be considered.