It is a rare point of agreement in a divided America: both Democrats and Republicans see benefits in geothermal energy. The same cannot be said for the UK, where the drilling technique central to the next generation of geothermal – hydraulic fracturing, better known as fracking – remains deeply controversial.
Geothermal energy uses natural heat below the Earth's surface, and new technology can access hotter, deeper locations than ever before. Low greenhouse gas emissions appeal to liberals; energy independence and familiar oil-and-gas drilling techniques appeal to conservatives. In April, US senators from both parties introduced the Next-Generation Geothermal Research and Development Act, which would direct the Department of Energy to support commercialisation of new systems.
“New geothermal technologies promise abundant clean energy but face economic and political hurdles, especially in fracking-wary UK.”
One emerging type is enhanced geothermal systems (EGS), which fractures underground rock by pumping pressurised fluid into one well and collecting steam or hot water from another. “It's the same techniques and up to a point it's the same industry as well,” says Gernot Wagner, a climate economist at Columbia Business School. But “from a climate perspective, there's a huge difference,” he adds. For Wagner, the risk of seismic activity from creating cracks underground is outweighed by the benefits of an energy source that is renewable, always-on and large-capacity. “Based on where we are, moving much faster, much bigger in the direction of using much more geothermal, frankly, is all good news.”
Yet in the UK, fracking has become highly controversial. The technique, used in oil and gas, is now being applied to geothermal under the EGS label. To go faster and deeper, drilling technologies must advance. Companies are developing more stable drills that can break through hard rock at high temperatures. Some aim to penetrate rock without standard drills.
Quaise, a company rooted at the Massachusetts Institute of Technology, uses millimetre wave drilling – sending electromagnetic waves to melt and vaporise rock. “Millimetre wave drilling really enables you to access super-hot geothermal just about anywhere,” explains Harry Kelso, Quaise's communications manager. Traditional geothermal clusters around hotspots where hot rocks are easily accessible. The new technique could unlock geothermal far from volcanic areas.
But the economics remain uncertain. Drilling costs are high, and commercial viability unproven. As Quaise and others push the technology, the question lingers: will the abundant energy under our feet ever be cheap enough to compete – and will a country like the UK, wary of fracking, embrace it?