One of Europe’s deepest metal mines, the Pyhäsalmi Mine in central Finland, is to be converted into a massive gravity battery capable of storing 2 megawatts of electricity.
As the world transitions to renewable energy, we face the challenge of storage. The problem is that the wind does not blow and the sun does not shine at the exact moment when people wish to use their energy. On unusually windy or bright days, excess electricity can be generated, resulting in a situation in which users are compensated to consume electricity rather than overburden the grid. But strength that is not used is lost.
It would be ideal, of course, if we could store that energy for later use. Gravity batteries are one method of doing this.
Despite the catchy moniker, the concept behind gravity batteries is quite straightforward. When energy sources provide more energy than is required, the excess energy is employed to drive weights (usually water or sand) upward, converting it into potential energy. When the power supply is low, these items can be released to power turbines as our good friend (and terrible enemy) gravity propels them towards Earth.
Though gravity batteries typically take the form of reservoirs, abandoned mines that move sand or other weights up when surplus power is generated have also been proposed. Gravitricity, a Scottish firm, developed a system of winches and hoists that can be installed in disused mineshafts. The technology will be installed at Finland’s Pyhäjärvi zinc and copper mine, which is 1,400 meters (4,600 ft) deep.
“As the world generates more electricity from intermittent renewable energy sources, there is a growing need for technologies which can capture and store energy during periods of low demand and release it rapidly when required,” Gravitricity co-founder Martin Wright said of the technology late last year.
“Our GraviStore underground gravity energy storage uses the force of gravity to offer some of the best characteristics of lithium-ion batteries and pumped hydro storage – at low cost, and without the need for any rare earth metals.”
