German energy company Uniper has officially opened a green hydrogen storage pilot at a salt cavern site at Krummhörn in northern Germany.

Kallanish understands the 3,000-cubic-metre Hydrogen Pilot Cavern (HPC) has a total storage capacity of about 500,000 normal cubic metres of green hydrogen. The trial operation will start with a gas tightness test on 24 September, Uniper said in a statement on Tuesday.

The company plans to expand the pilot facility to provide a storage capacity of 250 gigawatt hours (GWh) of hydrogen. Overall, Uniper plans to develop salt caverns for underground hydrogen storage with a planned capacity of 600 GWh by 2030, according to Doug Waters, managing director of Uniper Energy Storage.

The HPC Krummhörn project in Lower Saxony cost Uniper “a low double-digit million euro amount,” the company says. The project is also backed by around €2.4 million ($2.7m) from the regional government of Lower Saxony.

“Our HPC Krummhörn project is laying the foundations for the development of storage solutions on a commercial scale and is thus part of the implementation of our ‘Greener Gases’ strategy,” says Holger Kreetz, Uniper’s chief operating officer.

“Investments in the development of hydrogen storage systems require a clearly defined regulatory framework that incentivises initial investment,” the executive adds. “To achieve the objectives cost-efficiently and effectively, market-based storage fees should be coupled with a cost-regulated equalisation mechanism.” 

After the gas tightness test in September, the next step would be the initial gas filling and the plant’s operations with various injection and withdrawal cycles. Throughout the project, Uniper will test equipment and materials for hydrogen compatibility in a real environment.

In Bavaria, Uniper is also testing the integrity of porous rock storages for storing hydrogen. Under the so-called HyStorage research project, the firm is storing a mixture of natural gas and hydrogen in different phases at the former natural gas reservoir.