Battery parks and the fire risk but what's the safer option

Their purpose, in part, is to store in energy in a renewables-based electric grid in which supply fluctuates – and there are times when the wind doesn’t blow and the sun doesn’t shine – as does demand. They are an element in the plan for how we decarbonise energy and fight climate change.

But a wave of community campaigns against the sites, including fierce objection to a plan for a park at Cochno Road, have drawn attention to issues around their safety.

Jane Forbes, a campaigner with Save Our Countryside - Cochno Road said: “There must be a clear pause in allowing any battery energy storage sites construction in the UK until the necessary Safety and Regulatory procedures have been established by law.”

The problem, explained physicist, Dr Kurt Haselwimmer, is that “with lithium-ion battery parks it’s not just one little battery, like you get in your phone, but, literally billions of cells, all of which need to be working and all of which have the potential to enter thermal runaway.”

But defenders of lithium-ion battery parks note that with fire mitigation measures in place, the risks are relatively small, and that, globally, few such events have happened.

However, there is another type of battery, which doesn’t come with that risk – the vanadium redox flow battery. The technology has seen sudden expansion in China over the past few years, where, in Dalian, the world’s largest vanadium flow battery is smoothing electricity supply to over 200,000 residents, and enabling use of renewables.

Matt Harper, chief operating officer of Invinity Energy Systems, a vanadium flow battery company that has a manufacturing site in Bathgate, described this type of battery as “75% water – and because of that we joke that it’s as likely to put out a fire as start one.”

A worker at Invinity's Bathgate manufacturing site (Image: Invinity Energy Systems)

Mr Harper said: ““Our batteries are at their most fundamental level not flammable. The electrolyte, which is the core of the batteries  is non-flammable. We call it a flow battery because it’s a liquid that flows through the battery to enable the charge and discharge.”

This, he said, means that communities tend to be more comfortable with the batteries, compared to lithium-ion parks. “We’ve seen increasing opposition in the UK, America and elsewhere to having lithium-ion battery parks sited in places near where people live. That's because there is a significant fire risk.”  

Invinity currently has vanadium flow batteries in two sites in Scotland. One is at the European Marine Energy Centre in the Orkney Islands, where they play a role in smoothing out tidal energy in a system to produce green hydrogen. The other is at Scottish Water’s wastewater treatment site in Perth, where four batteries are used to store power generated from 2520 solar panels. 

nvinity vanadium batteries at Scottish Water's Perth wastewater treatment works (Image: Invinity Energy Systems)

But the company has also put itself on the map in Scotland in another way, by siting its manufacturing facility in Bathgate, choosing the site because of the “local workforce”, which, Mr Harper said, not only includes employees from manufacturing plants that had closed down in the area, but also "very talented and capable” people with transferrable skills from the oil and gas industry.

He said: “What’s exciting from our perspective about Scotland is that not only are we manufacturing the batteries there – but the amount of wind power that is being developed now and planning to be generated over the coming decade is enormous.”  

The technology behind the vanadium flow battery was first invented in the late 1980s. But it didn’t have the big boost that lithium-ion batteries had in their development for laptops, phones and cars. A chief reason why lithium-ions are being seen as a grid-scale battery option is that the technology and market are so developed.

There is now, according to physicist Kurt Haselwimmer a lithium-ion park goldrush, as companies clamour to put in applications - even though this option may not always be appropriate.

Dr Haselwimmer believes that part of the problem is that the challenge of how to create a secure, net-zero grid has been treated not as an engineering issue, but one that is to be solved via a market approach. “In the West,” he said. ”we have this idea we have to open everything up to private investment with almost unfettered market access and limited understanding of what will actually get built.”

“It’s a goldrush,” said Haselwimmer, “for several reasons.”

One of them he said, is that in its efforts to try to bring private money into the sector, National Grid ESO has essentially created a market for short energy storage services of duration of up to one hour. That duration seems to have been chosen precisely because the typical duration of a lithium-ion battery is one hour – not because that is what is needed.

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In that space, companies have rushed, creating proposals to get permissions and consent to join the grid, which they can then sell on as a prepackaged opportunity to people who actually have the money to create the parks.

The frenzy is driven, in part, by the fact that there are only a certain number of such batteries that are going to be needed on the grid – and, with over 900 applications on the energy consent system across the UK, the market is looking close to saturation.

But a key question is how useful is the duration offered by lithium-ion batteries? Is this type of storage even what the grid most needs?

Dr Haselwimmer does not believe so. Rather, he said, “the bulk of what we are going to need is longer duration storage, which is typically up to eight hours storage.”

This kind of long-duration storage is increasingly becoming seen as ideal when paired with solar energy, in which there is a mismatch between the sunniest time of day during which energy is generated in photovoltaic cells and the time when people, getting home from work and switching on their kettles and electric hobs will need to use it.

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Invinity batteries at Energy Superhub, Oxford (Image: Invinity Energy Systems)

A six-hour vanadium flow battery, in other words, is an ideal match for solar’s needs. But what about wind?

“Typically," said Invinity COO, Mr Harper, "very large batteries were installed alongside solar. We have not yet seen that in wind – and that’s partially because wind projects exist at a much, much larger scale than solar. A lot of wind farms are in the scale of GW capacity and the batteries to serve those wind farms would be larger than the largest batteries ever built.”

"But as that push," he said, "toward net zero becomes more clear – as the cost of electricity from wind turbines drops, and the cost of electricity from conventional gas and other fuel-based generation goes up, the imperative for more renewable generation is going to increase and therefore the need to have some way of matching supply and demand with wind is going to be ever more important.”  

Invinity has already been working with one of the world’s largest manufacturers of wind turbines on a joint development programme for their next-generation product, code-named “Mistral”. The aim is to deliver vanadium flow batteries most suitable for serving wind power.   

“What the wind industry likes about Invinity for very large wind projects is that they view our batteries as doing two important things very well – we can respond very quickly to smooth out any second-by-second variation in wind power production, and also store 6 to 10 hours of power when wind is good but demand is low then deliver that power when it is most useful.”   

Such batteries might be inserted in electricity networks at various points: at the point of electricity generation, at the point of consumption of electricity or within the grid to “alleviate some of the congestion constraints that exist between points of supply and demand”.   

They could be particularly key in enabling the smooth delivery of offshore wind power from Scotland to points of demand in England.  

Mr Harper said: “Some of the interconnections that exist between the generating capacity in Scotland and major sources of demand in the south of the UK have significant congestion points. Our batteries are an effective, proven way of relieving that congestion.”   

They also potentially, despite their lower energy density, could have a smaller or similar footprint on the ground. Unlike lithium-ion parks which tend to be a series of shipping container-style blocks, spaced out to prevent fire spreading if one does go off, vanadium flow batteries can be built vertically and without space in between. Because they are safer, they could also be installed close to where people live.

Vanadium, which is currently chiefly used for strengthening steel, is more common than copper, zinc, nickel, and, of course, lithium. Currently most of the world’s vanadium production is done by some of the world’s biggest steel-producing countries – China, Brazil, South Africa.

But Invinity hopes that in the future its batteries will use vanadium extracted from petrochemical waste streams, which often contain a high percentage of the element.

Mr Harper said: “Ultimately we would rather be using a material that is extracted from a waste product. That circularity is important to us.”

The UK Government is currently carrying out a consultation on 'Long duration electricity storage' which closes on March 5. The document states: "For the novel technologies that have not yet been proven at scale, such as compressed air energy storage (CAES), liquid air energy storage (LAES) and flow batteries, the lack of track record means it is harder to secure the required investment."

A Department for Energy Security and Net Zero spokesperson said: Battery storage parks are crucial in boosting our energy security and reaching net zero by storing renewable energy and releasing electricity where demand exceeds supply.

"Lithium-ion batteries are covered by a robust regulatory framework which requires manufacturers and industry to ensure products are safe before they are placed on the market."

For those at Cochno Road, campaigning against battery park developments, however,  it's not entirely about safety - it's about preserving a piece of land. It's not about vanadium or lithium, but a green space dear to them. Margaret Hamilton, a key voice in the protest said: "While we understand the government's push towards net-zero, our endavour is to preserve the greenbelt."