Hot rolling mills use reheating furnaces to bring the steel feedstock (e.g. billets, blooms, slabs) to a uniform temperature of about 1000 to 1300 ˚C until the steel is plastic enough for the rolling process. A 2020 study by Zanoni et al. said that furnaces for steel reheating are responsible for a large amount of energy consumption, where less than 50% of the energy supplied to the furnace (mainly gaseous fuel) is net energy of steel heating, the remaining is lost.
The plant in Hofors is also Sweden’s largest electrolysis plant, with a 20MW alkaline electrolyzer system from Nel ASA. Nel’s A Series atmospheric alkaline electrolyzers feature a cell stack power consumption as low as 3.8 kWh/Nm3 of hydrogen gas produced, up to 2.2 MW per stack. The A Series electrolyzer system at Hofors can produce up to 3,880 Nm3/h of hydrogen—just over 8 tonnes per day.
Electrolyzer system at Hofors. The large cylinders are the electrolyzer cell stacks; the white tanks visible at the rear are the hydrogen and oxygen separation tanks.
Our steel mill in Hofors was founded as early as the 16th century, and with the new hydrogen plant, we begin a new chapter in Swedish steel history. Heating steel products has previously required large amounts of fossil fuels. We are now the first in the world to heat steel with fossil-free hydrogen before rolling, reducing the emissions in this production step to almost zero.
—Marcus Hedblom, President and CEO Ovako Group
The fossil-free hydrogen produced in Ovako’s new facility will be used to heat steel at adjacent rolling mills, significantly reducing carbon dioxide emissions to nearly zero. In addition to steel heating, the hydrogen will be used for fueling fuel cell-powered trucks, and the excess heat from the plant will be used for district heating.
The fossil-free hydrogen plant in Hofors is the largest in operation in Europe. This solution for industrial heating technology holds the potential for substantial global emissions reductions, not limited to the steel industry, the company says.
Ovako is collaborating with partners such as the Volvo Group, Hitachi Energy, H2 Green Steel, and Nel Hydrogen. The development of the hydrogen plant has been supported by the Swedish Energy Agency and the European Union.
Ovako’s plan is to use local hydrogen production in all Ovako units where steel is rolled by 2030, provided there is good access to fossil-free electricity to power the electrolysis process.
Ovako is a subsidiary of Sanyo Special Steel and a member of Nippon Steel Corporation, one of the largest steel producers in the world.
