Abstract
Replacing fossil resources with green hydrogen in industrial production holds tremendous potential for greenhouse gas mitigation. The economic feasibility and greenhouse gas (GHG) mitigation of grid-based electrolytic hydrogen production is highly dependent on the time-variant price and carbon footprint of electricity. In the present contribution, we analyse the economic feasibility of transitioning key carbon-intensive industries, steelmaking, and ammonia production, to green electrolytic hydrogen. Also, we investigate the competitiveness of green electrolytic hydrogen with other environmentally sustainable hydrogen sources derived from biomethane, biogas, and natural gas (associated with carbon capture and storage). We perform process design for steelmaking, ammonia production, and biogas-based steam reforming in order to determine key performance indicators such as costs, conversion factors, and GHG emissions. In particular, we allow for dynamic operation of the industrial processes and hydrogen production to exploit temporal fluctuations in availability, price and carbon footprint of electricity. To this end, we solve bi-objective optimisation problems to determine optimal operational profile and sizing of the industrial processes, hydrogen plants, and (optionally) renewable power generation systems. Case studies are dedicated to the identification of (i) advantages of decentralised renewable energy installations in combination with flexible plant scheduling over steady-state production and (ii) the cost-optimal hydrogen production route. This is done for current (2020) and future (2030, 2050) German energy system scenarios. Based on the analysis results, we outline bottlenecks in sustainable steel and ammonia production and suggest short-term research goals to improve the competitiveness of green electrolytic hydrogen.