Think of battery manufacturing and it may evoke images of Elon Musk and Tesla’s sprawling “gigafactories” around the globe, or China’s vast, hi-tech clean rooms churning out cells to go in anything from electric toothbrushes to mobile phones and cars. But at Invinity Energy Systems’s small factory in Bathgate, near Edinburgh, workers slotting parts together are hoping that Britain can also play a part in the battery revolution.
These batteries, which rely on vanadium ions, are put in 6-metre (20ft), 25-tonne shipping containers. They will not go into cars, but the manufacturer hopes the technology can win a place in a global rush into storage to usher in the shift to net zero carbon grids.
Renewable electricity is the future of the global energy system: cheaper and cleaner than fossil fuels. However, its main drawback is that renewables generation is tied to the weather, and the sun may not be shining or the wind blowing at the times when energy is most needed. “Time shifting” that energy generation with battery storage, so it can be stored and used later, will be crucial to the proper functioning of electricity grids.
“What suddenly started to happen is that people have woken up to realise that energy storage is needed to be able to deploy more renewables on to the grid,” said Jonathan Marren, the Invinity chief executive, at the factory where a row of the batteries is stacked, ready to be shipped.
Experts have long been grappling with the different options for storing renewable power, but the issue of the reliability of grids rose up the political agenda in April when Spain and Portugal suffered the biggest blackout in Europe in 20 years. Some people rushed to blame renewable energy, although a Spanish government report said that was not the case. Nevertheless, battery storage could help grids around the world to avoid Iberian-style chaos.
The electricity blackouts in Spain and Portugal in April highlighted the issue of energy security. Photograph: Fermín Rodríguez/NurPhoto/Rex/Shutterstock
Much of the focus on battery research has been on cramming as much energy as possible into the smallest, lightest container to go into electric cars. That work has been crucial for the switch away from the carbon pollution from petrol and diesel, a key contributor to global heating. It has also forced down the cost of lithium ion batteries dramatically.
As with much of the transition away from fossil fuels to electric technology, it is China that is driving an increase in demand at an astonishing scale. China has installed batteries with a capacity of 215 gigawatt hours (GWh) – two-thirds of the global total – according to Benchmark Mineral Intelligence, a data company.
China’s battery installations are due to nearly quadruple by the end of 2027 to 826GWh, if all planned projects are completed. For instance, the state-owned China Energy Engineering Corporation last month tendered for 25GWh of batteries using lithium iron phosphate technology that is being used in cheaper cars.
Global battery storage capacity by country
Iola Hughes, the head of research at Rho Motion, a Benchmark subsidiary, said falling prices and the growth of renewable energy were driving the rise in demand. By 2027 total global battery storage installations could increase by five times to 1,500GWh, said Hughes, and “this figure could increase even further as advancements in technology and declining costs allow developers to build battery energy storage systems at a faster pace than historically”.
The vast majority of that rise – 95% on current numbers – will be projects using lithium ion batteries such as those being used in Aberdeenshire by Britain’s Zenobē Energy, which installed batteries with a capacity of 600MWh – enough to power all the homes in Scotland for an hour. They claim the site is “Europe’s largest battery”.
Energy storage companies using different technologies must now run the brutal gauntlet of finding early stage funding as they try to prove that their technology will be economical. Invinity’s flow batteries use vanadium, while in the US its rival Eos Energy is using zinc. However, flow batteries could find a niche for storage over six to eight hours – more than the two or so hours that lithium batteries tend to provide.
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Cara King, an R&D scientist at Invinity Energy Systems, seen holding vials of vanadium electrolyte in its different states of charge. Photograph: Murdo MacLeod/The Guardian
Flow batteries rely on the ability of some metals to exist stably with different numbers of electrons. One shipping container holds two tanks containing vanadium ions with different numbers of electrons – one “royal purple”, the other “Irn-Bru red”. A pump moves the vanadium liquid through a stack of membranes that allow protons to cross, while the electrons are diverted around a circuit, providing power. If electrons are forced in the other direction – by a solar panel or a wind turbine – the reaction moves in reverse, recharging the battery, which can hold 300 kilowatt hours of charge.
An important benefit of the flow battery is that it is much simpler to manufacture than lithium ion equivalents. Invinity has been able to make its stacks with 90 employees, mostly based in a part of Scotland that has deindustrialised.
Marren claimed that over the project lifetime “on a levelised cost basis, we are better value than lithium”. The upfront cost is still higher than lithium batteries – Invinity hints that it costs above £100,000 for a container – but the batteries last much longer without losing capacity, and are non-flammable, so do not need expensive fire safety equipment. The shipping containers are already sitting beside wave machines in Bristol, car chargers in Oxford, a casino in California and a solar park in South Australia.
“We can commission whole sites within days,” Marren said.
Invinity is valued at just over £90m on London’s Aim junior stock market, and it is hoping the UK takes a lead in the flow battery niche.
British manufacturing could count in its favour in a government competition for support under a “cap and floor” scheme that will guarantee electricity prices within a set range – removing the risk from a sustained fall in prices. If successful, the company would require a big production expansion from the current ability to make five containers a week, Marren said. He dreams of employing 1,000 workers if the company takes off.
“The potential for expansion is enormous,” Marren said. “We’ve gone past the stage of ‘does the tech work at scale’? We’ve got a long-duration storage that works.”