Miles below the Earth’s surface, there’s enough thermal energy to power all of humanity for the foreseeable future. It’s called geothermal energy, and it’s poised to play an increasingly large role as a source of always available, renewable power. Now, there are a number of startups in the geothermal space, working to figure out how to access this heat in difficult to reach geographies, at a price point that makes sense. And it’s even gotten the attention of oil and gas industry giants, who are interested in greening their portfolios while sticking to their core competencies – extracting energy resources from deep within the Earth.