Optimal integration of a solid-oxide electrolyser cell into a direct steam generation solar tower plant for zero-emission hydrogen production

Abstract

Steam electrolysis through Solid-Oxide Electrolysis Cell (SOEC) coupled with concentrating solar power (CSP) plants stands for a promising system of large-scale carbon-free hydrogen production process. This study presents an energetic analysis on integration schemes of a SOEC Unit into a direct steam generation solar tower plant. Several configurations have been analyzed aiming at minimizing the penalties of the integration over the CSP plant, and maximizing the electrolysis performance. Atmospheric and high pressure operation modes of SOEC have been analyzed.The results show that operating the stack at atmospheric pressure, penalties over the solar plant can be reduced by 60% if process steam is extracted from low pressure turbine section and solar plant feed water is preheated with rejected hot streams from the electrolyser. In high pressure SOEC scenarios, although penalties over the CSP plant are increased, the overall performance of the hybrid plant could be improved by 5.8%, and also oxygen could be collected as co-product if a pressure swing adsorption unit is integrated.