Oil companies and environmentalists have long been at odds, but a new area of common ground is emerging: geothermal energy. At a recent conference in Houston, Karine Kleinhaus from the Environmental Defense Fund addressed oil executives about the potential for oil industry expertise to help scale up geothermal power.

Geothermal energy—using heat from beneath the Earth’s surface—has been around for over a century. It is a reliable, low-emission energy source that operates like traditional fossil fuel or nuclear power plants. However, its high costs and geographic limitations have kept it from widespread adoption. Currently, it makes up only 1.6% of the U.S. energy mix.

Oil companies like Chevron, BP, and Shell have started investing in geothermal startups. Despite this, their spending on geothermal remains small compared to their fossil fuel investments. A major hurdle is profitability—geothermal must compete with the high returns of oil and gas projects. Without financial incentives or government backing similar to other green technologies like hydrogen, scaling up geothermal remains a challenge.