Abandoned Coal Mines Could Become Giant Underground Energy Storage Facilities

The U.S. has more than 500,000 abandoned coal mines on federal record, concentrated in Pennsylvania, West Virginia, and Kentucky. Researchers at Oak Ridge National Laboratory think many of them could have a second life as energy storage facilities.

The concept is called Pumped Storage Hydropower. Water gets pumped into a reservoir when energy is cheap, then released through turbines to generate electricity when demand spikes. It already accounts for more than 90% of utility-scale energy storage in the U.S. but has traditionally required mountains or significant elevation changes to work. Moving the operation into existing underground mine shafts could solve that geography problem and cut construction costs by using existing infrastructure.

ORNL has developed modeling tools to assess which sites are viable and how to manage the engineering challenges involved and a full economic analysis is the next step.

It’s a good reminder that many types of innovation are needed to meet our energy needs, and sometimes the answer is already there, underground.