Abstract
Renewable production of hydrogen offers a clean and sustainable replacement of fossil fuels. As an energy carrier hydrogen is compressed and stored at high pressures. Pressurized water electrolysis improves plant performance as hydrogen compression is an energy intensive process. This work analyzes hydrogen production over the temperature range of 100°C to 800°C and pressure range of 1 bar to 700 bar. The sensitivity of plant efficiency to hydrogen compression technology and waste heat recovery is investigated. This study reveals that a lower-heating-value electric energy efficiency of 84% can be achieved when pressurized electrolysis avoids the inefficiencies of hydrogen compression. With the availability of high-quality waste heat plant efficiency can reach 98% for a pipeline distribution scenario at 3MPa. When no waste heat is available plant efficiency is independent of electrolysis temperature. For hydrogen use in the transportation sector, pressurized supercritical water electrolysis at 800°C has the potential to improve plant efficiency by 14% from a baseline of non-pressurized electrolysis at 800°C.
