Storing Hydrogen in Salt Caverns Could Help Ensure Reliable, Flexible Power Generation

Underground salt caverns containing stores of hydrogen could provide a solution to the problem of back-up electricity generation in the years ahead.

Safe hydrogen storage

In a recent report, the Energy Technologies Institute (ETI), a public-private partnership between a number of global companies and the UK Government aimed at speeding up the development of low-carbon technologies, set out the contribution hydrogen and its storage could make to a clean energy system. According to Den Gammer, the report’s author, one cavern could accommodate enough hydrogen to satisfy the peak demands of an entire UK city.

Its flammability and the minuteness of its molecules make hydrogen gas hard to contain. It can, however, be safely stored in caverns surrounded by thick deposits of crystalline salt. Such salt deposits are located across the UK and caverns can be created using salt-mining techniques first employed by the chemicals company ICI (Imperial Chemical Industries). ‘Geologic’ storage – the use of caverns as storage facilities – is already being used for oil and natural gas, being far less costly than using tanks above ground and offering greater capacity.

Providing cover when renewables fall short

The importance of back-up power supplies will increase as the UK moves towards renewable energy. Wind, in particular, is intermittent, and not always strong enough to power the turbines.

Meanwhile, nuclear reactors produce a constant supply but can only do so economically if they run at full capacity, delivering what is called a ‘baseload’ supply – enough energy to meet the minimum demand over 24 hours. Similarly, fossil-fuelled turbines with carbon capture and storage (CCS) technology fitted cannot respond efficiently to fluctuations in demand and have to be operated throughout the year (except when undergoing repairs or maintenance).

But a UK-wide network of turbines running on hydrogen – just one of the solutions that will need to be developed and commercialised over the next few decades if the UK is to move towards a low-carbon energy system – would offer much-needed flexibility to our future energy mix. Underground stores of hydrogen could be released to the National Grid for electricity generation whenever it is facing a shortfall.

Hydrogen demand in the USA

Similar possibilities are being investigated in the USA, where the introduction of fuel cell electric vehicles could boost the popularity of hydrogen fuel. If this proves the case, large amounts of cost-effective hydrogen will need to be produced and stored before being distributed as high-pressure gas or liquid.

Other fuels are already stored geologically in the USA – for instance, in depleted oil reservoirs. But salt caverns, which currently store hydrogen on a limited scale, offer a safer and more viable storage solution because they are virtually leak-proof. On the debit side, salt formations are far from widespread, with none at all in the Pacific Northwest.

Whatever type of gas is used to generate our electricity or power our vehicles, and wherever it is stored, Exi Flow continues to supply quality products to enable its measurement. To find out more about our services call us on 01243 554920.