There are a few sources of energy that are “free” here on earth, namely wind, solar, hydroelectric and geothermal. Humans have been harnessing hydropower and wind for millennia, and we’re getting pretty good at harnessing the power of the sun. But with geothermal energy, we still don’t make expert use of the heat generated deep within the planet.
Most commercial-scale geothermal plants are located in geological hotspots such as Northern California and Iceland. On a smaller scale, many homeowners have drilled shallow wells or buried loops in their yards for heating and cooling. But to truly unlock the potential of geothermal energy around the globe, and to do so profitably, we need new ways to drill deep and harvest the earth’s heat.
As the world tumbles through an energy transition, many energy clouds are talking at length about responsive baseload power. That’s a lot of jargon. “Dispatchable” means that network operators can request a power generation system at short notice and deliver it. And “base load” means power that’s always available, no matter the weather. Renewable energies such as sun and wind are not base load energy in and of themselves. It’s a different story when they’re paired with batteries to store power for use when the wind is calm or the sun isn’t shining. The combination of renewable energy and batteries is becoming more common, but batteries remain expensive, and why not more options than just that?
To truly unlock the potential of geothermal energy around the globe and do so profitably, we need new ways to drill deep and harvest the Earth’s heat.
Geothermal energy is often touted as a carbon-free source of renewable baseload electricity, which is why energy wonks heat up for it. In a geothermal plant, a working fluid, often water, is injected underground, heated there before being drawn back up to flow through a heat exchanger or drive a turbine.
The heat source is almost unlimited. The Earth continuously produces about 44 terawatts of heat, about half of which comes from naturally occurring radioactivity. That’s about 385,000 terawatt hours of energy released each year, far more than global energy consumption, which was just under 23,000 terawatt hours in 2019. If we could tap into a fraction of the earth’s heat, we would have a lot of energy available.
The potential of geothermal energy coincides with the looming demise of the fossil fuel industry, prompting many engineers to reconsider their careers. Coincidentally, many of the drilling techniques developed for the oil and gas industry fit well with the requirements needed to make geothermal energy mainstream.
There are a number of start-ups trying to transform geothermal energy from a niche power source into a widespread energy source. Here are five that I have observed.
If there were an award for the sexy geothermal technology, Quaise Energy would likely be the winner.