How liquid air could solve the UK’s energy conundrum

Highview Power believes it has the pioneering solution to intermittent renewable power

Each year, Britain adds thousands of megawatts of renewable power to its energy mix as it races to reach its target of net carbon zero emissions by 2030.

But as the proportion of wind, solar and tidal power grows, so too does the lingering problem of intermittent energy.

One solution is to overproduce power on windy and sunny days and supply it back to the grid when there is a lull in renewable energy. But how?

Highview Power, based in London, believes it has a solution: use cryogenic liquid air to store the electricity until it is needed.

The pioneering technology works by compressing air into a liquid and then cooling it to almost minus 200°C.

The liquid air is stored in an insulated tank at low pressure, which functions as the energy store. When power is needed, liquid air is drawn from the tank and pumped to high pressure.

Stored heat from the air liquefier is applied to the liquid air via heat exchangers and an intermediate heat transfer fluid. This produces a high pressure gas, which is then used to drive a turbine and generate electricity.

Chief executive Rupert Pearce says the loss of energy during the process is around 50pc, but much of the waste is through heat which can be recovered, taking its potential to about 70pc.

"It's going to make a massive difference to the cost of energy for consumers, because, of course, our homegrown sovereign renewables are much, much cheaper than any other form of generation," he says.

The company now plans to raise £400m to build the world's first commercial-scale liquid air energy storage plant near Manchester by the end of 2024.

The plant's components will largely be made of steel, meaning less demand for hazardous or rare materials, such as those used in nuclear or battery-powered solutions. If the plant leaks, it will leak air. And despite the huge swings in temperature, the maintenance demands are low, says Pearce.

Still, it needs to make money. Pearce estimates that 3.5 terawatt hours of energy, enough to power the City of Liverpool, will be wasted in 2022 because the grid cannot handle excess wind power.

When this happens, wind farms are paid not to operate. With Highview's technology, that excess power can be stored. Highview will instead be paid to fill its tanks since it will be cheaper to do that than to pay off the wind farms.

Then, when demand exceeds supply, it can fire up its turbines and power the grid.

"We can provide them with the flexible demand, we can provide them with long term storage, so we can become a strategic reserve for the UK," he says.

Highview's plant in Carrington will have a 30 megawatts capacity and store 300 megawatt hours of electricity.

The company has 200 patents to defend its technology, says Pearce, although he hopes not to need them.

"I’m not losing sleep over the competition, simply because the market opportunity is so big. We were looking to put £10bn worth of equipment on the ground in the UK alone, and we are less than 50pc of the UK's energy storage needs."

Pearce joined Highview Power after 16 years at satellite company Inmarsat, leaving when it was bought. Before that he was a partner at law firm Linklaters.

"When I saw this company, I was hugely excited by its promise," he says.

The technology competes with pumped-storage hydroelectricity, which uses excess power to pump water uphill, releasing it through turbines to generate electricity.

The challenge is you need two lakes and some mountains for pumped hydro to work, making it unsuitable for much of the world, says Professor Yulong Ding of Birmingham University, who invented the liquid air energy storage technology being commercialised by Highview.

"You can store a lot more energy within a given volume or given weight compared with pumped hydro," says Prof Ding. There is also very little leakage, perhaps less than 0.1pc per day, he says. Like pump hydro, a few minutes’ notice is needed to start production, while the grid needs to be fed within milliseconds.

This is a gap which could be filled by battery packs, although Highview is hoping to use supercapacitors and flywheel storage to provide energy in the meantime.

Hydrogen is another contender, but storing it cheaply is a long way away, Pearce says.

So far, the company has received £10m from the Government to build its Carrington plant on the back of the success of a prototype in Pilsworth.

But raising the rest of the money is a challenge, says Pearce.

"It's very difficult for two reasons. The first is this is new technology," which tends to raise the price of capital.

The other reason is that infrastructure investors prefer dependable long-term offtake agreements, with a predictable income, he says, although he thinks it will be possible to win investors over once the next plant is built.

"As our product matures, the first one is built, we will show that it will work. The first one is built to deliver the revenues and we show the market model works," he says.

Once that happens, Pearce hopes to raise £10bn to build more plants in the UK as part of a broader energy storage market which could be worth $4 trillion.

Target areas in the UK include Humberside, close to where the power cables from offshore wind turbines make landfall, and Australia, which is suffering high gas prices and failing coal plants.

The need is growing. Power networks around the world are responsible for about a third of global emissions, he says, making transition in our electricity networks "absolutely pivotal to making a decent fist of reducing the impacts of climate change".

"Although it is obviously a cost to implement storage, the blending costs will still be materially below what consumers and businesses are paying for energy today. So there's a real opportunity here," said Pearce.