Analysis of the systemic potential and normal operation behaviour of grid-forming electrolysers to cover the future inertia demand

The high rates at which hydrogen electrolysers will need to be installed threaten the electricity grid's stability if specific grid connection requirements are not fulfilled in an analogue manner to generation plants. However, their flexibility may offer significant potential for covering electricity system demands. In addition, the transformation to a climate-neutral electricity grid leads to structural changes in providing system stability demands, such as inertia. This poses the research question: what systemic potential do electrolysers have to cover the inertia demand, and how does their grid-forming control affect regular operation? The systemic potential depends on the total installed electrolysis capacity and the realisable synthetic inertia of the plant. The latter, in turn, is influenced by technology-specific and plant-specific dynamics, partial load capability, overload capability, duration of generation, and the market share of capable plants and electrolysis types. Electrolysers offer a significant theoretical potential, particularly in the northern German federal states. In addition, inertia power is only generated at high-frequency gradients. Hence, the inertia provision in the European grid is less than 1 % for a significant part of the year, depending on the synthetic inertia constant.