As energy storage becomes increasingly critical to facilitating the UK’s transition to net zero, the market for battery energy storage systems (BESS) is seeing rapid expansion. The technology is not, however, suited to every application, and alternatives will have to step up to meet the requirements that BESS cannot.
One option is the use of supercapacitor technology. Uniquely suited to high-power applications, supercapacitors are a type of electrochemical energy storage that can charge and discharge at a far greater speed than batteries. Used in tandem with BESS, supercapacitors can extend the lifetime of a battery and reduce the size of the battery needed.
While we’re starting to see supercapacitor technology use by early adopters, breakthroughs in cost and performance are still required to bring it into the mainstream. Current± spoke to Hector Lancaster, one of the co-founders of Super6, a startup trying to revolutionise the technology.
Where do supercapacitors fit into the energy mix?
To contextualise them in the scheme of energy storage devices, supercapacitors would be like sprinters, high-powered for short periods. Batteries would be middle-distance runners and fuel cells run a marathon. Supercapacitors do not rely on chemical reactions, instead working by separating electrons—just like in electronic capacitors, but on a much higher surface area.
It is not a new technology, but it has not seen the same commercial breakthrough as batteries. We are only just seeing them come to market in ways that can make a difference to the energy transition. They are not in direct competition with, say, batteries and shouldn’t be; in a lot of applications, they can be complementary.
For example, grid application trials have seen supercapacitors meet the very fast frequency response needs for the initial ‘dump’ of power that is needed. Once that bit of requirement is met, the battery comes in and handles longer-term needs. This means the battery is not forced into high-power applications for extended periods, reducing battery heat and its degradation.
Also, supercapacitors use a lot fewer critical minerals than batteries, so as well as the sustainability gains you get from a longer battery life, you also limit the amount of critical minerals needed.
Because the battery does not need to be sized for power, the system can be smaller; you size it for energy, which is to say the steady-state stuff that it does well. In solar applications, for another example, you can have very small time-scale fluctuations, little variations that need to be handled somehow. If you have a supercapacitor, it handles all of that and can cycle many more times than the battery can.
How is Super6 enabling that type of use?
Because supercapacitors are still not very mature commercially, cost and performance improvements are necessary before they can compete with alternatives. We believe that with more awareness and further cost reductions, supercapacitors will become more commonplace. We think we can reduce the capex and opex when coupled with certain solar assets or wind assets and existing energy storage systems.
Value for Power (V4P) is intended to make supercapacitors much more affordable by cutting materials and processing costs. The target is current market standard performance at 80% of the cost, allowing market penetration for the technology. Super6 is using low cost materials and processing, In grid applications, the economics are incredibly important. If a supercapacitor is installed to work in tandem with a battery, you can ultimately save on battery cost and size, which is somewhere there is a real market.
We also have an Unparalleled Power (UP) project, which targets the performance side. It is a high-performance supercapacitor with a world record energy density, tested at the lab scale, that can store nine times more energy in total than what is out there at the moment. This is good for EVs, say, where there is a space and a volume requirement.
Which markets will the technology work in?
At the moment, being so new, the company is still at the point of technology development, making small scale pouch cells—the type of cell format in a mobile phone. Our two main focuses at the moment are development to a point where we can partner up to test some of the cells in a real-world application. The second is understanding where to go for that first application.
The UP supercapacitor speaks to applications that have a performance angle, so space and motorsports are an early target but it would lead into automotive and micromobility. V4P would be more for the side of thingsdictated by the economics of the application.
The potential market is vast: automotive, marine, heavy machinery, space, motorsport, rail, UPS, grid, aviation, and intralogistics. All of these need high-power applications for which, in some instances, people are trying to use batteries.
