It may appear unremarkable but however in Leighton Buzzard you find Britain’s biggest battery: a record-breaking pilot project that, its backers say, shows that electricity storage can play a vital role in the changing energy mix.

The lithium-ion within this system is similar to that in a smartphone battery but this project — with 200 tonnes of equipment containing 50,688 cells. “This facility would give your smartphone a talk time of about 1,800 years,” Ian Cooper, of UK Power Networks, says.

New housing developments meant that the town was outgrowing the capacity of its grid, leaving residents vulnerable to being short of power should one of its two circuits fail on a cold winter evening.

In the past UKPN would have dealt with such a problem by installing a new backup circuit, which would then have sat redundant for most of the year. Instead, it built a big battery. Capable of storing enough energy to produce six megawatts of power for an hour and a half — enough to supply about 6,000 homes at peak — the battery ensures that the grid is prepared to cope with a winter outage. At a cost of £12 million when it was built in 2014 it was roughly twice as expensive as a grid upgrade. However, it is significantly more useful.

On the bright spring morning when meeting peak demand is not a concern, but the battery is still in use. “It’s currently providing a frequency response service to National Grid,” Mr Cooper, UKPN’s senior technology transfer engineer, says. “So it could be charging or discharging — and change from one to the other fairly quickly.”

As Britain builds more wind farms and solar panels, which produce electricity only when the wind blows or the sun shines, keeping supply and demand in balance is becoming more challenging. To keep the lights on, the system needs flexible power sources that can respond quickly to short-term fluctuations to keep the grid frequency at safe levels, such as the service provided by the UKPN battery. Flexibility is also required to ensure that the grid is not swamped with too much power on a sunny summer afternoon or left short on a dark, still winter evening.

Batteries that can help to overcome renewables’ intermittency by storing power for when it is needed have long been the holy grail of the energy system. Now, thanks to rapid technological advances and cost reductions led by the electric vehicle market, they appear to be within reach.

Battery manufacturers that have ploughed millions into research to improve the energy density of battery packs.

BNEF estimates that prices for lithium-ion battery packs have dropped by 73 per cent in the past six years and are set to fall further. “Batteries have been very expensive,” she says. “However, because prices are falling so dramatically we are now seeing some cases where the utility or grid operators sees value in a battery.”

While the likes of Elon Musk’s Tesla have grabbed the global headlines with tests of grid-scale batteries in California, excitement has been growing in Britain too. A year ago the National Infrastructure Commission had enough confidence in the prospects for battery storage to identify it as one of three key pillars — along with interconnectors and flexible demand — that could help to reduce the costs of the transition to green energy.

Since then a flurry of large-scale projects — as well as domestic home battery trials — have got the go-ahead. In August National Grid awarded £66 million of contracts to developers of eight new British batteries to provide “enhanced frequency response” (EFR), adjusting their output in less than a second to help balance the grid quickly. EDF Energy and Eon were among the utility giants to secure contracts and EDF’s proposed project, a 49-megawatt battery in Nottinghamshire, is set to be the largest in Europe.

Then in December another raft of projects won subsidies through the government’s “capacity market” scheme to maintain power in winter 2020-21, including Centrica’s plan to build a 49-megawatt battery in Cumbria. In total, 52 projects with a capacity of 702 megawatts are contracted to be operating by 2020, according to analysis by Smartest Energy.

There is ongoing research on improving the duration of lithium-ion and we expect to see some improvement, but progress is slow.” Given the costs of innovation, Mr Price says, “there comes a point where other [battery] technologies might be more economic for long-duration dispatch”. Trials are under way around the country, including a lead acid project on Shetland, a compressed air storage site at Larne in Co Antrim and a flow battery project — which stores energy in liquid form — on the Isle of Gigha.

Jesse Norman, the energy minister, says that “the UK’s underlying strengths in science and energy technology mean it is in a perfect position to become a global leader in battery technology”. The government has asked Sir Mark Walport, its chief scientific adviser, to “consider the case for a new research institution for battery technology and energy storage”.

For a company such as UKPN, which also counts the avoided costs of a grid upgrade in its business case, falling technology costs mean that building more big batteries such as the Leighton Buzzard test project could be commercially viable. However, current regulations restrict network companies’ ownership of batteries. UKPN is lobbying to change this, as well as rules that it says mean batteries are double-charged for green taxes.

Mr Norman says that removing the “regulatory and policy barriers to storage” is the priority for the government, which will publish a “smart systems and flexibility plan” this spring. Official projections for the British energy mix suggested for the first time a rapidly growing role for batteries, with 1GW operational by 2021 and 4GW by 2033.

Mr Cooper believes that batteries can reduce the need for back-up power plants to meet peak demand. “If you don’t have storage, you’ll need vastly more power stations,” he says.

A brighter future for households – Moixa, a battery company, is working with Northern Powergrid to install batteries in 40 homes in Barnsley; Centrica, the energy supplier, is working with Western Power Distribution to install batteries as part of a trial “local energy market” in Cornwall; and UK Power Networks has offered discount installation of Powervault and Sonnen batteries in about 60 homes in its network areas in London, the South East and East Anglia.

For companies such as UKPN, the tests will show whether supporting home batteries could help to avoid costly grid upgrades.

 

Claire Curry, an analyst at BNEF, says: “Part of the reason utilities are looking at batteries is that, if they don’t, every homeowner could buy a battery and a solar panel and halve their consumption from the grid. That destroys the business of these utilities.”

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