Abstract (eng)
As energy systems need to be urgently decarbonized to meet climate protection targets, electricity systems must cope with the electrification of fossil-fuel powered processes. Simultaneously, they need to integrate increasing quantities of intermittent renewable electricity generation to achieve net zero greenhouse gas emissions. This poses an enormous challenge to existing electricity systems as they are designed for high shares of flexible fossil fuel based electricity generation. Operating completely renewable electricity systems, however, requires large flexibility to balance intermittent electricity generation with electricity demand without relying on readily available fossil fuels. In particular, electrifying large energy consumers such as the iron and steel (I & S) industry can therefore become a challenge for renewable electricity systems as they can fundamentally influence the operations of the electricity system. This study investigates the effects of directly or indirectly electrifying steel production on a completely renewable Austro-German electricity system. Thus, it represents an exploratory case study of how to successfully decarbonize the tightly coupled energy and industry sectors. The results indicate that flexibly-run H2 electrolyzers, flexible H2 gas power plants and utility-scale batteries will become crucial elements of a renewable electricity system in Germany in order to provide the necessary flexibility in the system to balance electricity generation and demand. In Austria, on the other hand, electrolyzers and H2 gas power plants are likely not required as central elements of a completely renewable electricity system as Austria possesses sufficiently flexible hydro storage units that are even able to supply inflexible electricity consumers at times of low intermittent electricity generation. Furthermore, the results show that the cost and energy efficiency of using a technology in individual plants may differ to the overall system costs and system energy efficiency as supposedly cheap and more energy efficient technology might require additional infrastructure on a system level to function.