This was a chemistry demonstration that did not go bang and pop. In a factory in Bathgate, two test-tubes of vanadium electrolytes were mixed, one purple and the other orange, and all that happened was the thermometer reading rose to 33C.
But that lack of explosivity, said Dr Elisha Martin, lead research scientist for Invinity Energy Systems, is the point. “With lithium batteries, there are many concerns about excessive heat generation, thermal runaway and eventual issues with fire and explosions. But this demonstration is designed to show that with our systems, we don’t have the same concerns.”
“Not only,” she added, as a flaming splint was put out by the electrolyte, “are we not concerned about thermal runaway in our electrolyte itself, but our electrolyte at any state of charge is actually capable of extinguishing fire."
With the fire-risk around lithium-ion batteries frequently in the news, along with community campaigns, like Save Cochno Road, fighting to prevent the construction of battery storage parks, the demonstration was showing the safety of an alternative type of battery.
For the past four years, Invinity Energy Systems has been making giant vanadium flow batteries using such electrolyte at this unit in Bathgate. It has now expanded, and opened a 26,000 square foot factory in Motherwell.
In Bathgate, an assembly-line, worked by five women, demonstrates the creation of the company's battery cells, which go into stacks and are then ultimately assembled into giant shipping container-sized batteries at the new Motherwell site.
But the safety of a vanadium flow battery is not its only virtue. The UK Infrastructure Bank has just invested £25 million in this company – and a key reason for this is in order to back a type of long-duration energy storage, the sort that is going to be needed to help stabilise the national grid, offering the ability to store energy for much longer than the 1-2 hours generally provided by lithium-ion batteries.
This follows a consultation by the UK Government, earlier this year, on 'Long duration electricity storage', its aim being to design a policy framework to enable investment in batteries like these.
The company sees its technology as very much aligned with Labour policies to accelerate the transition and create energy security, and the establishment of GB Energy.
Currently, National Grid forecasts show that up to 29 GW of total storage could be needed by 2030 and up to 51 GW by 2050, a huge increase on the 6 GW approx. currently available.
“In the UK,” explained Jonathan Marren, Invinity’s chief development officer, “we want to decarbonise the grid, and that can only come from nuclear or renewables. And, as we know, wind and solar is intermittent so it creates instability, even when it is operating. When the wind isn’t blowing and the sun isn’t shining, there is no generation. So you need storage alongside that in some shape or form.”
What’s needed, he observed, is chiefly storage over a 4-8 hour range. Longer term seasonal storage will also be needed eventually, but this is about dealing with daily peaks and troughs. “This,” he said, “is about cycling, that sort of shifting of power from day to night. At the moment lithium has been able to step in and pick up some parts of that.
"That’s why you have lithium batteries being deployed on the grid and they’ve obviously benefited from all the investment that’s gone into their use in mobile phones and EVs so the technology has got cheaper. But lithium can only go so far. It really is that 1-2 hour duration.”
A key use of Invinity’s technology will be as Battery Energy Storage Systems, the kind of battery parks which are seen as central to making a grid that is based around the intermittent energies of wind and solar work alongside the fluctuating demand of the consumer daily cycle. Currently most are comprised of lithium-ion batteries.
For the most part, till now, Invinity’s vanadium flow batteries have been used as storage alongside solar panel arrays and as ‘standalone’ systems positioned at key junctions on the electrical network.
Invinity also 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.
But their potential is wide. Not only could they form battery storage parks, but the next generation of the technology, code-named “Mistral”, is being developed in collaboration with Siemens Gamesa, to provide battery storage at a much larger scale – specifically with wind farms in mind.
“Invinity batteries,” said Marren, “could have an important role to play in relieving network congestion and allow more Scottish-generated low-carbon energy to be used across the whole of the UK.”
Last week, Invinity opened its new factory in Motherwell, with the promise of 41 jobs, in a century-old building that has made its own passage through various transitions, from bridge contruction to oil and gas industry parts, and now to batteries that are a key element of a renewables-based grid,
For Invinity, a key draw of the site was its 30 tonne-crane, since some of their units are 25 tonnes and every time they have had to bring units for work in Scotland, the company has had to hire a low-loader.
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Bathgate will manufacture the stacks of vanadium cells. Motherwell will assemble them into the battery units, which are housed in 20ft shipping containers, currently sourced from their supplier in China. “They’re made of steel," explained Marren, "and no one makes steel cheaper than China at the moment.”
The short duration and fears around the fire risk are not the only problems with lithium-ion batteries for storage and balancing the grid. There is also the pollution and environmental impacts of lithium production, as well as, potentially its price, and security.
“We have low lithium prices at the moment,” said Marren, “because demand for EVs has dropped. But do we think it’s going to remain the same forever? Probably not.”
Though those steel containers are made in China, a vast amount of the engineering, design and development work is conducted in Scotland as well as the battery assembly itself. As a result, Invinity sees itself as providing UK-made energy storage, in an industry dominated by Chinese manufacturers. Crucially, it's, a technology that is not dependent on lithium, whose supply is chiefly controlled by China, which has managed to secure an 80 percent share of global lithium chemical production.
Jonathan Marren said: “The units will either come with electrolyte, or we’ll buy electrolyte from a supplier in the UK. We try to use UK suppliers wherever possible, but they’re still quite small, hopefully they will be able to supply us in greater volumes in the future.”
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.
“As the UK looks to electrify,” said Marren, “we are going to need more storage. So long duration storage technologies are absolutely needed. And that’s why there are lots of businesses chasing that area, flow batteries are one of a number of potential solutions.”
“The answer is there probably needs to be many different technologies. We think there is a market for flow batteries and we think we are one of the dominant players. If we get our product right and our cost right, then there will be a decent market for us.”
The Motherwell site is not just aiming to be a manufacturer of the batteries. This is where Invinity also hope to connect some units to the grid and start trading electrical energy, providing further proof of their product. “The hope,” said Jonathan Marren, “is that we can connect four up in Motherwell at the far end of the site, and get someone to trade them for us.”
The goal of this would be to generate a set of trading data, since, while there is plenty such data for lithium ion batteries, of duration 1-2 hours, there is very little around these longer cycle batteries, of 4-6 hours storage. The company knows the batteries work. The technology is proven. At Bathgate, an engineer demonstrates its rapid charge and discharge - a cycle that takes moments to achieve.
“But,” said Marren, “that doesn’t tell you how much money they are making for the client – and the client tend to keep their trading data proprietary to them."
So far Invinity’s only set of trading data has is being generated by Spencer Energy in Australia , a solar PV farm which is using an Invinity battery to create 10 GWh of dispatchable solar power per year. The data is already looking good. “This,” said Marren, “was probably the first time we were able to get some trading data."
Invinity's UKIB funding is designed, in part, to allow them to set up projects connecting to the grid and create that data. “What they realised was that us having some access to some trading data can come from us co-owning some of the projects, so £18 million of that £25 million can be used to co fund some projects. We intend to deploy that, alongside some customers.”
Invinity is also keen to create jobs and develop skillsets in Scotland. “The chemists out there are all from Scottish universities,” Marren said. “They’re supportive of bringing more people in. We can reskill people from the oil and gas industry as part of the transition.”
But a barrier to running their Motherwell battery connection to the grid is the queue that there remains for connections. “We’ve got batteries ready to deploy now. If we had sites that we could connect those batteries up to we would start to work on that now. But grid connection is an issue.
“There is a use-it-or-lose-it approach which has come in now, but it needs to become a bit more meaningful, because use it or lose it is in the space of 3-5 years. We would love to be connecting some of these batteries now to the grid and there just aren’t the places to do it.”
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