US Secretary of Energy Jennifer Granholm on Tuesday said the United States needs to boost domestic production of the minerals used to make electric vehicles, so long as it is done sustainably.

The United States has been trying to wean its automobile supply chain off of China and other countries for years, with mixed results.

President Joe Biden signed an executive order last month requiring greater coordination among federal agencies on supply chain issues, but many environmentalists have vowed to oppose new US mines.

Still, the United States is reliant on China for lithium, rare earths and other EV minerals, a situation that Biden and Granholm have called untenable.

"Many parts of the country are sitting on top of the materials that we need to produce battery technologies," Granholm said at a webinar hosted by Securing America's Future Energy, a nonpartisan advocacy group for renewable energies.

Granholm, who said she drives an electric Chevrolet Bolt from General Motors Co, said that there would be "huge demand" for a sustainable mining process that extracted and refined minerals in the United States, though it was not immediately clear how she defined that term.

Granholm also suggested coal miners - who have been affected by falling demand from the power-generation sector - could transition to digging for EV metals.

"Having (coal workers) mine for critical materials is a natural shift for them," said Granholm, a former Michigan governor who was confirmed last month as secretary.

The Energy Department last week said it would re-open a clean energy loan program with more than $40 billion.

The department's scientists are working on reducing EV charging times to less than 15 minutes for a car to go 300 miles (483 km) and also to help reduce the cost of battery packs, which would make EVs more affordable, Granholm said.