System analysis of a fossil free steel manufacturing plant powered by an offshore wind power farm

Abstract: Major changes are taking place in the Sweden’s electricity system and steel industry. Through political agreements, the current government has set national goals of 100% renewable electricity generation and a net zero GHG emissions industry by 2040. This will be achieved by increasing renewable power generation, mainly wind power. In the steel industry, the steel manufacturing groups are beginning to transition to an electricity-based steel manufacturing processes to reduce their GHG emissions. The Swedish steel manufacturing group SSAB and the mining group LKAB, together with Vattenfall, are developing an alternative steel production process free from fossil-based sources. It is called HYBRIT, an alternative technique to reduce iron ore with hydrogen gas, instead of coal which is used today. By producing hydrogen with electrolysis, applying hydrogen reduction technology, and replacing coal powered blast furnaces with electrified arc furnaces for melting the steel, it is possible to create a green and environmentally friendly steel industry. This technique was simulated in a computer model where electricity flows and system component capacity requirements were calculated. The simulation was made of an existing steel manufacturing plant in Oxelösund. A hypothetical case was made where the plant has a fully incorporated HYBRIT steel production chain. Its main power source was a nearby offshore wind power farm which is a planned project by Svea Vind Offshore. Previous studies have simulated HYBRIT steel manufacturing in computer models. However, no similar studies have been made on how these systems operate with variable availability of renewable power. From two studied wind power farm layouts, the results found a relationship between the needed electrolysis capacity as a function of the concentration recycled steel used in the process and the yearly steel production demand. Using the stated goal of SSAB where they use 50% recycled steel as a reference, it was calculated that 286 – 309 MW electrolysis unitsis needed for a yearly steel production of 1.6 million tonnes.