There are some energy sources that are “free” here on earth, namely wind, solar, hydropower and geothermal energy. Humans have been tapping into hydropower and wind for millennia, and we’re getting pretty good at harnessing the power of the sun. But with geothermal energy, we are still not making skillful 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 dug-in loops in their yards for heating and cooling. But to really unlock the potential of geothermal energy around the world, and do it profitably, we need new ways to drill deep down and bring up the Earth’s heat.
As the world winds through an energy transition, many energy wonks talk at length about switchable base load power. That’s a lot of jargon. “Dispatchable” means that grid operators can ask a plant to produce power at a moment’s notice and it will deliver it. And “baseload” means power that can always be on, regardless of the weather. Renewable energy sources such as solar and wind are not base load energy in themselves. It’s a different story when they’re linked to 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, so why don’t we have more options?
To truly unlock the potential of geothermal energy around the world, and to do so profitably, we need new ways to drill deep down and extract the Earth’s heat.
Geothermal is often presented as a carbon-free source of controllable baseload energy, which is why energy wonders are hot for it. In a geothermal plant, a working fluid, often water, is injected underground where it is heated before being drawn back up to flow through a heat exchanger or drive a turbine.
The heat source is almost unlimited. The earth generates continuously 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 use, which was in 2019 just under 23,000 terawatt hours. If we could tap into a fraction of the geothermal heat, we would have a lot of energy at our disposal.
Geothermal’s potential coincides with the looming decline of the fossil fuel industry, leading many engineers to rethink their careers. Coincidentally, many of the drilling techniques developed for the oil and gas industry align well with what is needed to make geothermal energy mainstream.
There are a number of startups trying to transform geothermal energy from a niche energy source to one that can be deployed on a large scale. Here are five I reviewed.
Quaint Energy
If there was an award for sexiest geothermal technology, Quaint Energy would probably be the winner.
