Director of the UK’s Electricity Storage Network Jill Cainey said: “It doesn’t always rain when you need water, so we have reservoirs – but we don’t have the same system for commercial electricity.”
This may well change in 2016 however, as industry professionals predict a breakthrough year for energy storage, something considered vital to the large-scale introduction of renewable energy across the UK. In turn, customers’ energy bills are also predicted to fall.
Currently big batteries are leading the way, with their costs falling considerably in the last few years, but a wide variety of other technological solutions have sprung up – from existing schemes, such as splitting water to make hydrogen, compressing air in underground caverns, and heated gravel pits, to long term ideas such as supercapacitors and superconducting magnets.
The first plant to store electricity by compressing air into a liquid is due to open in the UK in March, while steps have been taken to create the first virtual power station made up of a network of home batteries.
“We think this will be a breakthrough year,” says John Prendergast at RES. A UK company, RES has 80MW of lithium-ion battery storages operational around the world, with six times that currently in development – including the first UK project at a solar park near Glastonbury. “All this only works if it reduces costs for consumers and we think it does,” says Prendergast.
The reason energy storage is so important for renewables is not because green energy is unpredictable, in fact in some ways it is more predictable than traditional energy sources, but because green power can be intermittent. Strong winds generating energy in the early hours of the day do not coincide with the peak demand in the evening. Storage will solve this problem by keeping the energy ready to be used when it is needed, and thus maximising the output of windfarms and solar arrays.
However, on its own the amount of efficiency gained here would not be enough to warrant the costs of storage. Fortunately, energy storage comes with a host of other benefits. Currently the UK’s National Grid spends £1bn a year juggling power usage around the country in order to keep the lights on. Having access to stored energy could play a big part in solving this issue.
Storage is also a much more viable solution than building a whole new power plant that might be idle for most of the year, only coming into production during the peak demand times of winter evenings. Wide distribution of storage would also have a large effect on the UK’s energy security.
Prendergast calls energy storage “a ‘no regrets’ option”.
Currently, the most widespread form of energy storage involves pumping water up mountains when there is excess energy and then letting it flow back down through turbines when demand exceeds supply. The UK has four of these plants, but construction of more is limited by the geographical necessities of the design. Highview Power Storage has an alternative, however: liquid air.
Funded by the Department of Energy and Climate Change (Decc), Highview has created an £8m demonstration plant near Manchester which is set to begin operation in March. In the plant, air is compressed 700 times until it is a cold liquid using excess power. When more power is needed the air is released to become a high pressure gas which turns a turbine. The current 5MW system could power several thousands of homes for a few hours. CEO of Highview Gareth Brett likened the system to pumped storage, but added that the benefit is that it can be built anywhere.
The Decc has also backed another energy storage solution in the form of a home battery created by Moixa Group, similar in design to Tesla’s Powerwall. The briefcase-sized battery costs £2,000 and can store energy from rooftop solar panels that isn’t immediately used. This battery then forms part of a smart network of similar batteries in other homes, sharing electricity and forming a virtual power station to balance the National Grid. CEO and Moixa founder Simon Daniel says about 350 systems have been installed so far and argues that the system is much faster to implement than waiting for planning permission for large energy storage sites.
“Sky installed satellite dishes in a third of UK homes in seven years,” Daniel says.
The Moixa batteries are lithium-ion, the mainstay of grid-scale energy storage rollout globally. In the past the technology was too expensive to be practical, but costs have fallen in recent years and widespread use in consumer technology has given investors confidence.
Currently, the UK’s biggest operating energy storage system is an £18m battery plant in Bedfordshire. Martin Wilcox from UK Power Networks, the company that built the plant, said the company had to decide between building a third main power line into the area or installing 6MW worth of batteries. Due to the money earned from balancing the gird, the second option seemed the most feasible. The plant went live in 2015.
The UKPN plant is soon to be beaten by a new project in Northern Ireland however. AES, a global power company, is building a 10MW lithium-ion plant in Kilroot. REDT is also installing a £3.6m flow battery on the Scottish island of Gigha to store energy from its wind turbines.
East Anglia also has its own battery project. Everest is a project undertaken by Future Transport Systems that uses second-hand batteries from Renault electric cars. It buys the batteries at a fraction of the cost of new ones when they are 75% degraded from the continuous stop-start nature of driving. Once FTS has them they are then charge and discharged slowly, giving them an extra five to six years of use.
According to Mark Thompson at Innovate UK, a government agency, using car batteries as smart storage while they are still inside cars is a good option for the future. He says there could be around 4GW of capacity on the roads in the UK by 2025 due to the 300,000 electric cars projected to be in use by then. By comparison, the average nuclear power station contains about 1GW of capacity.
Mr Thompson points out that for 95% of the time cars are stationary, and using them as storage could save billions of pounds.
Despite the growing interest in energy storage, the UK is starting from a low point. Currently there is only 24MW of storage out of the 5,000MW the Committee on Climate Change says is required by 2030.
Audrey Fogart from Younicos, a German energy storage company operating in the US, said: “The UK and Europe really led the way on renewables, with the US following. But the opposite seems to be the case in the energy storage industry.” California alone has mandated an extra 1,200MW of storage by 2020.
Decc said it was still deciding how to use the £250m given to it for non-nuclear energy innovation, but “expect to have increased funding” for energy storage.
Energy secretary Amber Rudd said in November: “Locally generated energy supported by storage, interconnection and demand response, offers the possibility of a radically different model … We are looking at removing regulations that are holding back smart solutions, such as demand side response and storage.”
Although that would be welcomed by UKNP, Wilcox says the current system was not designed for storage and is inhibitive to progress. As an example, he says UKNP has to pay towards government social and green subsidies when it buys electricity to charge its batteries, but then customers pay the same fees a second time when they take the power from the discharging battery.
Highview praised the Decc for sticking with them as “a British technology” but says regulation issues are preventing the speedy rollout of storage.
Cainey says storage projects can be built very quickly, within 18 months, and praised California for its commitment to tackling climate change.
“California is aggressively pursuing a low-carbon agenda and they don’t want diesel [generator back-up] on the system,” she said.
The UK was recently criticised for awarding £175m of subsidies to highly polluting diesel generator farms.
Prof Ian Arbon at the Institute of Mechanical Engineers, who called energy storage the “missing link” in the UK’s energy plans back in 2014, said: “As a nation we are nowhere near where we should be on energy storage. There is a clear need for massive and urgent attention. Energy storage is one of the obvious solutions to the [decarbonisation] problems we face.”
The government has rolled out plans to build new gas-fired power stations and develop fracking infrastructure. Arbon said: “The UK is the only country in the world who thinks it is going to hit its renewable targets by doing more with fossil fuels.”