https://www.sciencedaily.com/releases/2023/05/230526121105.htm

"We found that coal can be this geological hydrogen battery," said Shimin Liu, associate professor of energy and mineral engineering at Penn State. "You could inject and store the hydrogen energy and have it there when you need to use it."

Hydrogen is a clean burning fuel and shows promise for use in the most energy intensive sectors of our economy -- transportation, electricity generation and manufacturing. But much work remains to build a hydrogen infrastructure and make it an affordable and reliable energy source, the scientists said.