Compressed hydrogen storage

Overview of the status and impact of the innovation



Compressed hydrogen is a storage form whereby hydrogen gas is kept under pressure to increase the storage density. It is the most widely used hydrogen storage option. It is based on a well-established technology that offers high rates of charge and discharge. However, because of hydrogen’s low volumetric value – three times less than methane under standard conditions – the high-pressure requirements (350-700 bar) leave roughly 15% of the hydrogen energy content to be consumed. Compressed hydrogen can be stored in cylindrical vessels made with materials that resist diffusion and embrittlement (see Box 9.1 for example projects). In addition, purified and compressed gaseous hydrogen can be stored in underground salt caverns (Vattenfall, 2022).


The ability to store and transport hydrogen decouples its production from its supply and use. Storage is crucial for securing supply for end users, such as industry clusters, and for the creation of a global hydrogen market (see Box 9.1 for an example from Norway). Storage also adds flexibility to renewable power generation, beyond that provided by electrolysers, since it allows short- and long-term storage of hydrogen (over entire seasons) produced during periods of high renewable power levels for use when renewable generation and hydrogen production are low. In the long term, large-scale hydrogen storage facilities must be in place to realise the full value of the green hydrogen economy.

BOX 9.1 Examples of compressed hydrogen storage projects

The Los Angeles Department of Power and Water’s Intermountain Power Project (United States) plans to replace coal as the fuel for a 1 800 MW power plant in Delta, Utah, first with natural gas and then with a mix of gas and green hydrogen, with the share of hydrogen increasing to 100% by 2045. The plant has access to abundant wind and solar power, and any surplus hydrogen produced by on-site electrolysers will be stored in a large geologic salt dome under the plant for use later (even a whole season later) when electricity demand is high. The repowered plant is expected to enter operation in 2025 and begin burning a mixture with 30% green hydrogen in 2026 (Maloney, 2019; Los Angeles Department of Water & Power, 2020).

The Green Hydrogen Hub (Denmark) intends to be the first project using large salt caverns to couple large-scale green hydrogen production with both underground hydrogen storage and compressed air energy storage. By 2030, the project expects to have an installed electrolyser capacity of 1 GW, 400 GWh of hydrogen storage and a 320 MW compressed air energy storage plant (Green Hydrogen Hub, 2022).

The Deep Purple Project (Norway) combines offshore wind turbines, offshore electrolyser units and storage tanks on the seabed for storing pressurised green hydrogen (Lee, 2019).

The Hypster Project (France) aims to store hydrogen in salt caverns for use in industry and transportation. The project, which was launched in 2021, uses a 1 MW electrolyser to produce 400 kg of hydrogen per day and will initially be able to store 3 tonnes of hydrogen for several months or years in underground caverns. The project will help determine the cost of hydrogen storage, the quality of hydrogen extracted from caverns and the role and importance of underground storage in the hydrogen ecosystem (Hypster Project, 2020).