Why UK needs to get moving on large-scale energy storage

If the UK is to keep the lights on then it must ramp up construction of large-scale electricity storage, says a Royal Society report.

The independent scientific body looked at various ways to store surplus wind- and solar-generated electricity, including green hydrogen, advanced compressed air energy storage, ammonia and heat, and concluded that large-scale electricity storage is key to meeting UK climate targets.

The report, which was published just before Prime Minister Rishi Sunak reversed many of the UK’s net-zero policies, says that construction must start on large-scale hydrogen storage facilities if the country is to meet its previous pledge that electricity will come from low carbon sources by 2035.

“Electricity can be stored in a variety of ways, including in batteries, by compressing air, by making hydrogen using electrolysers, or as heat,” says the Royal Society.

However, added Sir Chris Llewellyn Smith FRS, lead author of the report: “The need for long-term storage has been seriously underestimated. 

“Demand for electricity is expected to double by 2050 with the electrification of heat, transport and industrial processing, as well as increases in the use of air conditioning, economic growth and changes in population. It will mainly be met by wind and solar.” 

These are the cheapest forms of low-carbon electricity generation, he said, “but are volatile—wind varies on a decadal timescale, so will have to be complemented by large-scale supply from energy storage or other sources.” 

The report, called Large-scale Electricity Storage, says gigawatt-hour-scale storage will be needed to complement current short-term reserves from lithium-ion battery plants to manage fluctuations in wind and solar power generation, especially those stemming from long periods of calm weather. 

The most cost-effective approach identified for storing excess renewable energy is the use of salt caverns to store hydrogen. Drawing from 37 years of weather data, the report predicts that by 2050 the UK will require up to 100 terawatt-hours of energy storage.

This amount must be capable of satisfying approximately a quarter of the UK’s current annual electricity demand. To put this into perspective, the capacity is akin to more than 5,000 Dinorwig pumped hydro dams. 

Located in Wales, Dinorwig has a capacity of more than 1.7 GW, making it one of the largest pumped hydro storage plants in the world. 

Multiplying this capacity thousands of times is impossible with current battery or pumped hydro storage and would require the creation of around 90 clusters of 10 caverns. It is unclear whether there is currently appetite to invest in such an ambitious energy infrastructure programme, however. 

Sunak raised eyebrows when he announced that the deadline for the sale of petrol and diesel vehicles, originally set for 2030, would be extended to 2035, and a timeline for phasing out gas boilers by 2035 would also be adjusted. 

These changes are expected to result in increased emissions over the next decade. The Prime Minister didn’t specify how these increases might be balanced by reductions in other areas. 

Alok Sharma, a former Tory cabinet minister who chaired the landmark COP26 climate summit in Glasgow, warned against backtracking on climate targets.  

“Rolling back on certain policies will mean we need to find emissions reductions elsewhere if we are to meet our legally binding near-term carbon budgets and our internationally committed 2030 emissions reduction target,” he said.

Phasing out gas boilers and banning sales of new petrol and diesel cars by 2030 were key parts of the UK’s nationally determined contributions to the 2015 Paris agreement on climate change.

Sam Hunter Jones, a lawyer at ClientEarth, told The Guardian: “Rolling back on existing policies risks going against a Paris agreement cornerstone of increased ambition, just months before COP28 negotiations. 

“The UK will now need to go even further in other areas, when it submits its next round of international climate commitments, to ensure the overall package is stronger rather than weaker.”

The report from the Royal Society underscores the urgency of large-scale energy infrastructure investment if the government is serious about meeting net zero targets.

Other options for substantial energy system decarbonisation include nuclear power, gas with carbon capture storage (CCS) and bioenergy. Although nuclear and gas with CCS are expected to contribute to the net zero goal, they come with substantial costs. 

Large-scale energy infrastructure investment is urgent

Sir Peter Bruce, vice president of the Royal Society, said: “Ensuring our future electricity supply remains reliable and resilient will be crucial for our future prosperity and wellbeing. 

“An electricity system with significant wind and solar generation is likely to offer the lowest cost electricity but it is essential to have large-scale energy stores that can be accessed quickly to ensure Great Britain’s energy security and sovereignty.”

Integrating hydrogen with adiabatic compressed air energy storage or other methods has the potential to reduce the overall cost of electricity and decrease the necessary levels of wind and solar energy supply. 

Salt caverns are among the most stable of geological formations and are already used by the National Archives and museums to store historical records. Britain currently has three hydrogen storage caverns in the UK, which have been in use since 1972. 

The report emphasises the need for innovative business models and market frameworks to incentivise the construction of the additional caverns required to make this plan work.

Llewellyn Smith added that while nuclear, hydro and other energy sources are expected to have a role, theoretically the UK could be powered exclusively by wind and solar energy. 

Green hydrogen reserves would be supplemented by smaller-scale storage systems based on batteries, which can respond quickly to the grid’s needs. 

The report author also anticipated that although overall the cost of electricity would be higher than in the last decade, it would be much lower than in 2022.

To meet Britain’s needs in 2050, “construction of large hydrogen stores must begin in the near future,” the Royal Society says. “There is also a need for large-scale demonstrations of other storage technologies. 

“If the incentives that will be required to catalyse the necessary investments are not in place soon, Great Britain will not have the storage that will be required when it is needed.”