Stable electrolytic hydrogen production using renewable energy
Keelan O’Neill, Fuyu Jiao, Saif Z.S. Al Ghafri, Eric F. May, Michael L. Johns
Abstract
• Modelling approach to design electrolysis systems for stable hydrogen production. • A hybrid combination of wind and solar is required for stable hydrogen production. • The LCOH is most sensitive to the electrolyser capacity. • Australian grid-based backup is only suitable for < 10 % of hydrogen generation. • Achieving stable hydrogen output costs ∼ 22 % more than cost-optimised systems. The inherent intermittency of upstream solar and wind power can result in fluctuating electrolytic hydrogen production, which is incompatible with the feedstock requirements of many downstream hydrogen storage and utilisation applications. Suitable backup power or storage (hydrogen or energy) strategies are thus needed in overall system design. This work conducts technoeconomic modelling to design electrolytic production systems featuring stable hydrogen output for various locations across Australia, based on hourly weather data, and determines the levelised cost of hydrogen (LCOH), emissions intensities and annual electrolyser usage factors. A stable, truly green hydrogen supply is consistently achieved by imposing annual usage factor requirements on the system, which forces the system modules (i.e. solar, wind, electrolyser and hydrogen storage) to be oversized in order to achieve the desired usage factor. Whilst the resultant system designs are however very location-specific, a design that ensures a 100% usage factor costs approximately 22% more on average than a system design which is optimised for cost alone.