Every time Britain has a still, grey week in winter, something invisible happens behind our plug sockets: gas power stations fire up to keep the lights on. That gas is often imported, with prices set by volatile global markets. This is one reason why energy bills surged during the cost-of-living crisis, despite the low cost of available renewable energy.

On very windy days, we have a different problem. The grid can’t always use all the electricity our wind farms generate, so we pay them to switch off. In effect, we throw away clean energy because we have nowhere to store it.

Our latest research, published in the journal Applied Energy, points to a solution hiding under the North Sea. The depleted oil and gas fields that powered Britain for half a century could be refilled, this time with hydrogen made from our surplus wind and solar power.

We found that suitable depleted North Sea fields could provide 3,659 terawatt-hours of hydrogen storage capacity, equivalent to more than seven years of projected UK electricity demand in 2040. Using them could also take conventional gas power stations off the grid altogether by 2040.

What is green hydrogen?

Hydrogen is the simplest and most abundant element in the universe, and can be used to produce energy without releasing carbon dioxide. Most hydrogen produced is “grey”: stripped out of natural gas in a process that releases carbon dioxide. “Blue” hydrogen is made the same way, but with some of that carbon captured and stored. “Green” hydrogen is different: it’s made by passing renewable electricity through........

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