It is hard to get Democrat and Republican politicians to agree on much at the moment, but the benefits of geothermal energy is one rare area of consensus. The next generation of technology can access hotter, deeper and more varied locations than ever before, making use of natural heat below the Earth's surface. Broadly, the low greenhouse gas emissions of geothermal plants appeal to liberals, while conservatives like the additional energy independence of geothermal, plus the use of drilling technology familiar in the oil and gas industry.
Some US states are trying to accelerate permits for geothermal plants, and in April senators from both parties introduced the Next-Generation Geothermal Research and Development Act. The legislation would direct the Department of Energy to support the development and commercialisation of the next generation of geothermal energy systems. One emerging type is known as enhanced geothermal systems (EGS), where underground rock is fractured hydraulically by pumping pressurised fluid into one well and then collecting steam or hot water from another well.
“Geothermal energy gains rare bipartisan US support, but costs and fracking concerns remain hurdles for the UK.”
Better known as fracking, this technique has become well known and controversial, particularly in the UK, in the oil and gas industry. "It's the same techniques and up to a point it's the same industry as well," sums up Gernot Wagner, a climate economist at Columbia Business School in New York. But "from a climate perspective, there's a huge difference," he adds. For Wagner, the risk of seismic activity, by 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," Wagner says.
To go faster and deeper will require advances in drilling technologies. Companies are developing drilling equipment that is more stable when breaking through hard rock at high temperatures. Some firms are even aiming to penetrate rock without using standard drills. Quaise, a company with roots at the Massachusetts Institute of Technology (MIT), is using a technology called millimetre wave drilling. The frequency is similar to that of microwaves. "Sending electromagnetic waves in the microwave millimetre wave spectrum to essentially melt and vaporise through the rock," explains Harry Kelso, Quaise's communications manager.
Traditional geothermal energy clusters around hotspots on the earth's surface where very hot rocks can be easily accessed. Millimetre wave drilling really enables you to access superhot rock at depths of up to 20km, potentially unlocking vast amounts of clean energy. But the economics remain challenging, and the technology is still unproven at scale. For the UK, where fracking remains a political hot potato, geothermal could offer a less divisive alternative – but only if the costs can be brought down.