May 14, 2020: UK gravity storage system firm Gravitricity has signed an agreement to build a 250kW demonstration system at Port Leith, in Scotland, it said on May 8.
The £1 million ($1.25 million) project involves using excess electricity from the grid to winch 12,000-tonne weights up a 16m high rig, then releasing them to send power back to the grid when needed.
The weights are made of steel and filled with iron ore.
Gravitricity has signed a land rental agreement with Forth Ports to build the demonstrator. While this project will be tested using a tall grid from which the weights will be lowered and raised, the ultimate aim is to make use of existing disused mine shafts, which have the required height for dropping the blocks and releasing energy.
“This grid-connected demonstrator will use two 25-tonne weights suspended by steel cables. In our first test we’ll drop the weights together to generate full power and verify our speed of response,” said lead engineer Miles Franklin.
“We calculate we can go from zero to full power in less than a second — which can be extremely valuable in the frequency response and back-up power markets.
“We will then run tests with the two single weights, dropping one after the other to verify smooth energy output over a longer period. Together, this two-month programme will confirm our modelling and give us valuable data for our first full-scale 4MW project, which will commence in 2021.”
The demonstrator should be up and running by late December, the firm said.
To finance the demonstrator, Gravitricity raised more than £750,000 in a crowdfunding campaign. It has also received a £640,000 grant from the UK government agency Innovate UK.
Dutch winch specialist Huisman is working with the company to build the prototype and identify potential sites in Europe.