Sweden’s green steel pilot project a success with commercialisation now underway

ENGINEERS have declared that their attempts to produce fossil-free steel have been successful and their industrial consortium will now press ahead with commercialising the technology. The team behind the Hybrit project in Sweden have produced a report outlining what has been learned during six years of pilot trials in what could prove a revolutionary phase in the decarbonisation of steel production.

Jenny Greberg, board member of Hybrit Development, said: “It has been a groundbreaking journey in a short period of time. The results from the pilot phase show that the process works and that we are ready for the next stage.”

Hybrit – short for hydrogen breakthrough ironmaking technology – is a collaboration between iron ore producer LKAB, energy firm Vattenfall, and steel manufacturer SSAB. The project was launched in 2016 to phase out the use of coal in steel production and prove that it can instead be made using green hydrogen and electricity. The prize for doing so would be a huge cut in emissions. The steel industry is responsible for 10% of Sweden’s total output and 7% across the world.

What have the pilot trials shown?

The pilot projects ran from 2018 to 2024 and focused on fossil-free production of iron ore pellets; hydrogen-based reduction of iron ore, hydrogen production through the electrolysis of water; and production of crude steel by melting sponge iron in an electric furnace.

The start of the steelmaking process begins with the production of iron ore pellets from high grade magnetite. Conventionally, this involves heating the feedstock with fossil fuels to fuse the iron ore particles together but retain their porosity. To avoid the emissions from burning fossil fuels, the team built a pilot plant in Malmberget that trialled the use of bio-oil instead. In 2023, the plant produced 3.6m t of pellets and the team estimates it saved 50,000 t of CO2 emissions.

Eliminating coal for iron ore reduction

The iron ore pellets are then reduced – that is the oxygen is removed – to produce pure iron. In conventional blast furnaces, coal is used. Hybrit built a pilot plant in Luleå that instead uses hydrogen, which can be produced by splitting water with renewable energy to eliminate emissions. Iron ore pellets are fed in at the top of a furnace and the bed of pellets slowly moves downwards as an upward steam of hot hydrogen gas reacts with the oxygen in the pellets, to produce water which leaves as steam from the top of the furnace.

Luleå produced its first fossil-free sponge iron in 2021 and has since run tests lasting six to eight weeks at a time, for a total of 61 weeks to 2024.

During the trial, engineers tested 175 different process states to characterise the mechanisms of the process. They tested different process conditions, varied the compositions and temperatures of the reducing gas, and the pressure and residence time in the furnace. The pilot has produced more than 5,000 t of fossil-free sponge iron and the team says the validated process has now been handed over to LKAB and SSAB for full-scale implementation.

Melting in a furnace

The sponge-iron was then turned into crude steel using a 10 t electric arc furnace in Luleå. This involves feeding the iron into a furnace with slag formers, biocarbon, and oxygen, where it is melted using electrodes powered by renewable electricity. The team carried out more than 400 melt trials, testing batch and continuous feeds and varying the amount of oxygen, carbon, and composition of the slag. The trials added up to 12 weeks of continuous testing time and produced more than 1,000 t of steel. This has already been used by customers including in cars made by Volvo.

Significant carbon savings

For each tonne of steel produced using this method, around 5 kg of carbon dioxide was emitted due to the oxidation of the graphite electrodes used in the melting process. This is a significant saving over conventional blast furnace production where around 2,200 kg of CO2 is produced for each tonne of steel. Meanwhile, conventional direct reduction that does not use hydrogen can produce between 64–383 kg of CO2 depending on how much fossil carbon is added during the reduction step.

All the hydrogen used during the trials at Luleå was produced using commercial alkaline electrolyser, which ran for more than 9,000 hours. The team also tested storing hydrogen 30 m below ground in a rock cavern with the capacity to store 100 m³ at 25 MPa. The trial showed that storing hydrogen can reduce costs by 40% compared to producing it on demand.

Greberg said: “The results from the pilot phase show that the process works and that we are ready for the next stage, where the demonstration plant that LKAB plans to build in Gällivare will be the first step towards industrial production of sponge iron.”

The team has now entered the demonstration phase of the process and expects to industrialise fossil-free steel production by 2035.