(Luleå / Sweden) – In Luleå in northern Sweden, the steel company SSAB, the mining company LKAB and the state energy company Vattenfall AB have inaugurated the pilot plant called “Hybrit” for storing hydrogen in rock caverns. 
This begins a two-year test phase. The technology has proven itself well and has been used to store natural gas in southern Sweden for around 20 years, explains Vattenfall. Now the process called LRC (Lined Rock Cavern) is “taking a step forward” with the development of a storage system for gaseous hydrogen. The cavern is filled and emptied at the rhythm of hydrogen production.
Produce steel without emissions
The energy source is intended to significantly reduce emissions in the production of steel. While in conventional steel production the oxygen is removed from the iron ore using carbon and coke in a blast furnace (reduction process) in order to obtain pig iron, in the Hybrit process this happens via direct reduction using hydrogen at a lower temperature, 
and sponge iron is produced in pellet form. Several sponge iron pellets are pressed together to form a briquette and then melted in an electric arc furnace. The first was in Luleå last summer Test production of 100 tons of sponge iron. The production of fossil-free hydrogen at high power levels, such as strong winds, and the use of the stored gas when the power grid is strained ensure continuous production of sponge iron.
The “Hybrit Development AB” joint venture between the three companies was founded in 2016. The companies want to create a completely fossil-free value chain from the mine to the finished steel and introduce the new low-emission technology. In this way, SSAB could reduce Sweden's carbon dioxide emissions by ten percent, it said in a statement.
Capacity 100 cubic meters
Construction of the storage facility using LRC technology began in May 2021. It is located approximately 30 meters below the surface and 100 meters from the entrance. The walls are lined with a waterproofing layer. 
The pilot plant has a size of 100 cubic meters. At a later date, storage with a size of 100.000 to 120.000 cubic meters may be required. In this case, up to 100 gigawatt hours (GWh) of electricity could be generated from the hydrogen - enough to supply a sponge iron factory for three to four days. 
SSAB, LKAB and Vattenfall are investing a total of 259 million crowns (24 million euros) in the hydrogen storage itself, divided into three equal parts. The Swedish Energy Agency is contributing a further 72 million crowns (6,7 million euros).
“The pilot plant is important to test and understand how hydrogen storage works on a large scale,” says Klara Helstad, head of the sustainable industry department at the Swedish Energy Agency. This is “an important piece of the puzzle” for a fossil-free value chain in the iron and steel industry, but also for a future electricity system.
Large-scale production of sponge iron in Gällivare
The next step is planned for 2026 with a demonstration plant for the production of fossil-free sponge iron on an industrial scale in Gällivare. Hybrit technology will then be used there on a large scale. The construction of further sponge iron factories is then planned. “LKAB needs to become one of Europe's largest hydrogen producers and this pilot project will provide valuable insights for further work to create the world's first fossil-free value chain for the iron and steel industry,” says Lars Ydreskog, Senior Vice President Strategic Projects at LKAB.
Photo above
The interior of the rock cavern. © Vattenfall AB
Class schedule
Schematic structure of the access to the storage facility. © Vattenfall AB
Photos (in the text from top to bottom)
Cavern area from a bird's eye view. © Vattenfall AB
Hydrogen tank. © Vattenfall AB
Base of the hydrogen tank. © Vattenfall AB
