Energy Shift Breathes Life Into Old Mines
From Europe to North America, former coal mines are transforming into renewable energy storage sites. These abandoned shafts now serve as gravity batteries, storing excess energy by lifting and lowering heavy weights. When solar and wind generate more power than needed, this energy lifts containers filled with sand or rock. Releasing them later produces electricity by converting gravitational force into power.
An abandoned coal mine [AI Image]
Solving Renewable Energy Storage Gaps
This storage method offers solutions to two major problems. It revitalises disused coal sites and supports renewable energy storage. With solar expected to surpass coal in global use this year, storing renewable power becomes urgent. During the UK’s 2020 lockdown, the National Grid warned of blackouts due to unused renewable power. Gravity batteries can prevent similar situations by saving surplus energy for later use.
Early Projects Lead the Way
China connected the first grid-scale gravity battery in Rudong in December 2023. It stores up to 100 megawatt hours, enough for nine homes for a year. Nine more projects are underway across China. In Switzerland, a similar system joined the national grid in 2019. Countries including Finland and Australia are also exploring this storage method.
Linking Past and Present Infrastructure
Many mine shafts are already deep, often over one kilometre. Their depth provides the vertical drop needed for gravity batteries. Engineers can reuse existing structures, cutting construction costs. According to Chris Yendell of Gravitricity, “Fundamentally, to make a storage project economically effective, having a significant vertical distance is key.”
A deep mine shaft [AI Image]
Using Brownfields and Mine Lands
The Nature Conservancy called former mine lands a “critical, underutilised resource” for renewable storage. The U.S. has about 550,000 abandoned mines. The EPA identified 20 million acres of brownfields and former mines suitable for solar generation. These could produce 1,300 gigawatts annually, powering over 200 million homes.
Global Energy Storage Potential
The International Institute for Applied Systems Analysis estimates abandoned mines could store 70 terawatt-hours globally. This could power the UK for three months. Mines over 200 metres deep suit Underground Gravity Energy Storage (UGES). These systems retain energy without discharge, making them reliable over time.
Boosting Coal Communities’ Economies
Gravity batteries also help coal-dependent regions join the green economy. The U.S. Inflation Reduction Act offers incentives for fossil-fuel communities. “The IRA is designed not just to lower energy costs and combat climate change,” said Wally Adeyemo. “It is also to create jobs in communities that have been at the forefront of energy production.”
Funding and Incentives Open Doors
Communities may qualify for extra tax credits for clean energy projects. The Nature Conservancy says these credits can help convert brownfields into clean energy hubs. Estimated global energy storage investments could reach $50 billion annually by 2040. Targeted support helps communities make the transition.
Revitalising Social and Economic Ties
Christopher McDermott from Edinburgh University highlights the social value. “These legacy mine workings are more than just structures,” he said. “They hold a long history and social legacy.” Using these mines again connects generations and rebuilds local identity.
Addressing Challenges and Costs
Old mines present risks, including structural damage and liability. Katherine Vaz Gomes from the Kleinman Center noted, “The challenge isn’t just the engineering; it’s the risk.” Some mines hold coal ash or asbestos, increasing remediation costs. Gomes recommends expanding the U.S. Superfund program to cover such projects.
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Policy and International Projects Advance Efforts
Germany’s LEAG is converting Lusatia’s lignite mines into a green hub. It will feature solar, wind, hydrogen, and batteries. Australia’s AGL Energy is turning Liddell Power Station into a 500-megawatt storage site. Finland’s Pyhäsalmi Mine will host a Gravitricity-led UGES project.
Seasonal Storage with Long-Term Value
UGES systems offer 80 percent efficiency and can store 10,000 hours of energy. They provide stable supply during winter when renewable output falls. These systems last longer than lithium-ion batteries, which degrade with time.
Honouring the Industrial Legacy
“Reusing these spaces developed by past generations is very positive,” said McDermott. “It creates a sense of continuity.” Turning coal mines into energy storage sites respects history and builds for the future.
A New Energy Future Begins Underground
With proper support, legacy mines can lead a global shift to renewable storage. Reliable energy from gravity batteries offers a way forward for communities and the grid.
