A first-of-its-kind underground storage facility for green hydrogen — a vital component to produce zero-emission steel at commercial scales — has been inaugurated in Sweden.

Green steel consortium Hybrit (Hydrogen Breakthrough Ironmaking Technology) — a pioneering collaboration between Swedish utility Vattenfall, mining group LKAB and steel producer SSAB — has opened its new pilot facility in Luleå, northern Sweden, marking the first time a lined rock cavern (LRC) has been used for subterranean H2 storage.

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“Green steel” uses renewable hydrogen instead of carbon-intensive coke (a form of coal) to extract iron from iron ore, and clean energy in every other part of the production process. The ability to store large quantities of hydrogen would therefore be a vital part of commercial-scale green steel manufacturing, due to the need for a constant flow of the gas, which cannot be produced when the wind is not blowing or the sun is not shining.

“The hydrogen storage facility will play a very important role in the overall value chain for fossil-free iron and steel production,” Hybrit said. “Producing fossil-free hydrogen gas when there is a lot of electricity, for example when it is very windy, and using stored hydrogen gas when the electricity system is under strain, will ensure a steady production of sponge iron [the pure iron metal extracted from iron ore].”

It is therefore “a way to make fossil-free steel competitive”, Vattenfall told Recharge, while declining to explain the cost savings the facility might deliver.

Storage capacity for the pilot project is only 100 cubic metres, but this could be expanded to 120,000 cubic metres — the equivalent of about 3,000 tonnes, or enough to supply a full-size sponge iron plant for three to four days, according to Hybrit.

According to the International Energy Agency (IEA), hydrogen is already stored underground in salt caverns some locations in the US and UK, but the H2 is never rapidly injected or extracted as is required for storage that responds to fluctuations in weather conditions.

“The [storage] pilot plant is important in order to really test and understand how large-scale hydrogen storage works,” said Klara Helstad, head of the sustainable industry unit at the Swedish Energy Agency.

“Storage of hydrogen gas will be an important piece of the puzzle for a fossil-free value chain for the iron and steel industry, but also in a future robust electrical system.”

Hybrit has already delivered what it claimed was the world’s first fossil free steel in August last year, from sponge iron made at the pilot project.

The storage pilot will now undergo a two-year test period, until 2024.

LRC technology, in which gas is stored underground in a rock cavern lined with a sealing layer of material, has been used to store natural gas in Sweden for around two decades, but the Luleå project marks the first time it has been used to store hydrogen gas, Vattenfall says.

Several other underground hydrogen storage projects are in the works around the world, including the Advanced Clean Energy Storage project in Utah, which received a $500m loan guarantee from the US government last week, and the Gasunie-owned Hystock project, which injected first hydrogen into a salt cavern in the Netherlands in 2021 and hopes to be operational by 2026.

Operators of the 6.3MW Hychico hydrogen plant in Argentina are also working on underground storage, as is Austrian energy storage specialist RAG, which is conducting an H2-focused storage research project on a natural gas reservoir, which it hopes to complete by 2025.

The Hybrit coalition’s next step is to build a pioneering industrial-scale demonstration sponge-iron project in Gällivare, some 250km from Luleå, by 2026 after it landed $158m in EU grants for the scheme.

“Hydrogen gas and its storage are central to our transition. In four years, Hybrit technology will be used on a large scale in the first demonstration plant in Gällivare, and the plan is to then build more sponge iron factories,” said Lars Ydreskog, senior vice president of strategic projects at LKAB.

“LKAB will therefore need to become one of Europe’s biggest hydrogen producers, and this pilot project will provide valuable knowledge for the continuing work on creating the world’s first fossil-free value chain for the iron and steel industry.”