With enough investment, geothermal power could satisfy 10 percent of the US energy diet, energy experts say.

Could hot rocks miles below the earth’s surface be the “killer app” of the energy industry?

Google thinks so. It’s investing more than $10 million to develop new technology that would make this subterranean resource a widespread, economically viable competitor to fossil fuels.

Geothermal heat could meet 10 percent of America’s energy needs by mid-century, according to the US Department of Energy. What’s more, it would not generate the climate-warming carbon emissions associated with fossil fuels.

Once tapped, a geothermal system would stay online for centuries. Unlike wind and solar, it would be a “base load” energy source, available 24 hours a day, 365 days a year.