Back in September, Karine Kleinhaus, a director at the Environmental Defense Fund, addressed an auditorium of suit-clad oil industry executives at Halliburton’s Houston headquarters. It was a bit of an awkward scene. “We’re looking to tackle climate change, which means stopping greenhouse gas emissions, which means transitioning away from fossil fuels,” Kleinhaus said onstage. “We can sugarcoat it or not, but that’s where I’m coming from.” That may have been Kleinhaus’s starting point, but the primary topic of discussion was one where the interests of the fossil fuel companies and environmental groups may align: how to use oil companies’ money, infrastructure, and expertise to rapidly scale up a new generation of geothermal power.