Edinburgh company Gravitricity is developing a system that
uses mine shafts to store and supply energy to the National
Grid.
The system is the brainchild of serial inventor and
technical director Peter Fraenkel. Peter previously worked
with Gravitricity’s chairman Martin Wright when developing
similarly innovative work for Marine Current Turbines.
Managing director Charlie Blair joined Gravitricity in 2015
after leaving the Carbon Trust. He was looking for a
low-carbon innovation to help lower emissions more
directly.
Charlie said: “Using gravity to store energy is already
commonplace in pumped hydro, but using a solid weight has
many advantages. There are a few companies out there that
are using weights, but Peter is really great at simplifying
things.”
Peter Fraenkel’s innovation was to hoist and suspend
weights over disused mine shafts then use the power
generated by lowering the weight inside the shaft to
rebalance supply quickly.
Charlie added: “We’re responding to second-by-second or
minute-by-minute imbalances on the Grid, which is more
valuable. Our system has a lot of versatility, focusing
initially on power.”
Independent analysis by Imperial College London supported
the company’s claim that gravity energy storage was more
cost-effective than current alternatives as well as being
cleaner and having greater longevity.
Like many heavy engineering projects, Gravitricity has a
timeline of five to six years before it can begin to recoup
cost. The initial grant of £175,000 from Innovate UK
solidified the concept in 2017.
“We had put a patent in, but there wasn’t really any push
to do anything,” said Charlie. “The funding from Innovate
UK enabled us to employ a couple of people and get moving.”
More mechanical engineers led to further innovation,
including the development of a multi-weight concept that
increases the flexibility and power of a single system.
Project development manager Chris Yendell started working
for Gravitricity after the second Innovate UK grant of
£650,000 was awarded in 2019. His work is currently focused
on the company’s scale 250kW concept demonstrator, which
will be installed in Edinburgh; later he will begin
developing a full-scale prototype.
Chris said: “Working at Gravitricity, we’re really
motivated by the cause. It’s more than ‘just a job’. The
end goal is something we all believe in.”
The company has also built a strong working relationship
with Dutch company Huisman Equipment BV to help
Gravitricity develop its winches. Gravitricity is also
building relationships in Eastern and Central Europe, and
South Africa. Partnering with countries who still have
working mines enables the company to work with mining
specialists, which gives them an indication of where
Gravitricity might go in the long term.
“The initial plan is to deploy in existing mine shafts,”
said Chris, “but we’ve done feasibility on sinking new
shafts and deploying where it’s needed, which includes
right in the middle of a city or near a wind farm. We’ll
carry on doing R&D work on that and hopefully work with
Innovate UK to achieve it.”
