Dennis Gammer gives his views on hydrogen storage

8th July 2015

Salt caverns are used throughout the world to store natural gas and other hydrocarbon products and hydrogen (H2) can be used to generate power.

But what happens if you combine the two? Could it be possible, feasible and a cost effective part of the UK’s future energy mix?

At the Energy Technologies Institute (ETI) we have completed an assessment of the potential into using salt caverns to store hydrogen for power generation when the demand for electricity peaks daily.

We have found that hydrogen storage could be potentially important in a future low carbon energy system because it could deliver clean, grid-scale load following power at a competitive price.

The UK’s energy landscape is changing very rapidly. More renewable power supplies are being installed and, although clean, these new supplies are often intermittent, which increases the need for a low cost, clean, on-demand power supply as back up.

We have undertaken a techno economic study carried out for us by Amec Foster Wheeler into the technologies used in hydrogen production, the stores themselves and the power plants that convert hydrogen into electricity.

The equipment needed to convert fossil fuel, biomass or waste into H2 ,and capturing and storing the co-produced CO2 with Carbon Capture and Storage (CCS) is expensive, so we don’t want that to be idle during periods when power is not needed.

The ability to store H2 means that you have the ability to keep all that equipment running at peak efficiency all of the time and fill the store with excess capacity. When power is needed, most of the H2 fed to the turbines to generate electricity can come from the store. Only the turbines need to be sized for peak demand loads.

The equipment producing H2 can be sized for the average load. This may be much smaller. Hence overall the equipment required for the peaking and load – following sector can be made smaller and cheaper than building new equipment which is sized for the peak demand, but only used for a few hours a day.

Salt caverns are man-made underground holes created by washing salt out of large geological structures made almost of pure salt.

Over 30 large caverns are in use in the UK today storing natural gas and the study focused on areas where they are already in use - Teesside, East Yorkshire and Cheshire. These are all at different depths and have different cost structures. A large cavern could supply the peak power requirements of a city the size of Hull. There are a handful of caverns worldwide storing H2 today.

So yes, It does seem feasible and attractive to add H2 storage to the various options we have when rebuilding our ageing power sector with cleaner technologies. Once bulk H2 is available in such stores, it could be used to help decarbonise other sectors such as industry or transport through the use of H2 fuel cells. Other technologies could contribute to H2 generation or its conversion to power.

The ability to store H2 changes inflexible gasification and reforming technology into competitive components of a highly flexible system offering  load following power services based on fossil fuel, biomass or waste fed power stations.

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