long-forgotten coal mine shafts—by repurposing them into places to store renewable energy. Using "gravity batteries," these underground facilities aim to tackle one of renewable energy's ...

From Europe to North America, an energy revolution is breathing new life into empty, long-forgotten coal mine shafts—by repurposing them into places to store renewable energy. Using "gravity batteries ...

The first stop is the No. 9 Coal Mine and Museum in Lansford, Pa., where the group will take a guided tour into a once-active underground coal mine ... Visitors can examine the original 700-foot-deep ...