Looking Again at Geothermal

September 21, 2020

Breakthrough Institute:

US and global expectations for geothermal technology are quite modest today, in part because it’s use has been limited to where geothermal energy can be easily accessed — in the western US and in geologically active countries like Iceland and Indonesia.

That could be changing thanks to recent advances in “Enhanced” Geothermal Systems (EGS). This new technology gives reason to think geothermal’s potential in the US and worldwide is much higher than typically assumed.

But that potential is not a given. If a future with high geothermal capacity is to be realized, EGS requires smart innovation policy to accelerate its deployment and bring down costs.

Geothermal has never truly been a priority for clean energy development in the US. The “forgotten renewable” generated only 0.4% of US electricity in 2019, which accounts for a whopping 20% of geothermal’s entire global electricity production. Outside of a few plants in California and four other western states, there are no existing US geothermal power plants. Despite its unique benefits and lack of emissions, it is relatively expensive and there is scant mention of it as a linchpin of proposed decarbonization plans.

A seminal 2019 Department of Energy report on geothermal, GeoVision: Harnessing the Heat Beneath our Feet, suggests there might be as much as 120 gigawatts of US geothermal electricity potential by 2050 in a best-case scenario — certainly major growth over today’s ~2.5GW, but far short of technologies like nuclear or solar on a ~1500GW and growing grid.

But this modest estimate fails to consider just how large the potential is for EGS costs to decline. Thanks mostly to the shale revolution’s breakthroughs on drilling with diamond drill bits and directional drilling, we have gotten much better at drilling deep holes cheaply, making geothermal more widely feasible for development. (Ironically, those breakthroughs in the natural gas sector were first discovered from early geothermal research.) One estimate quantifies the increase in access at around 1300 times what used to be available only using conventional geothermal extraction techniques. In the United States, most of this energy is west of the Rocky Mountains (shown below).

Given new technological advances and inconsistent progress, we don’t really know what the upper limit of deployed geothermal in 2050 could be. Many studies report fairly low central predictions of global geothermal energy but have upper estimates orders of magnitude higher. A 2008 paper on geothermal predicts 140GW of global geothermal capacity in 2050, but states: “The potential may be estimated orders of magnitude higher based on enhanced geothermal systems (EGS)-technology” — as much as 2,000 GW. A 2010 IPCC paper estimates between 50 and 200 GW of geothermal electricity in 2050, but states that between 2,000 and 4,000 GW is possible depending on “economics, demand, material constraints, and social factors.”

In other words, geothermal energy isn’t limited by the potential resources, but by the cost of the technology to retrieve it.

EGS technology might now be in the same place that solar or unconventional natural gas was in 1990. Neither became affordable by accident, but rather from decades of sustained government support. The concept of EGS has been proven, the background research and seismic mapping done, and the first test wells drilled. The challenge now is not to build the first EGS plant, but the 10th.

Few studies have analyzed the potential for deeper geothermal cost reductions from learning by doing. That means little work has been conducted to assess how costs could fall if experiential learning occurs at the scale it did for solar or unconventional natural gas. One analysis by a Princeton student modeled what would happen if similar learning rates occurred for geothermal.[1]In her model, cost reductions from experience curves could drive several 100s of gigawatts of EGS electricity in the US alone. The model suggests a compelling point — if actual geothermal costs fall with deployment in a manner consistent with experiential learning, cost reductions will be much greater than current estimates suggest, leading to even further geothermal deployment.

6 Responses to “Looking Again at Geothermal”

  1. mtpccl Says:

    I watched https://www.rff.org/events/advanced-energy-technologies-series/future-geothermal-energy/.

    Tim Lattimer of Fervo Energy discussed how he realized that the skills he developed in the oil and gas industry for directional drilling etc. could be readily applied to geothermal production and started his company. Good transfer.

  2. mtpccl Says:

    Spelling correction: Latimer

  3. J4Zonian Says:

    Here’s some data for Alaska, which seems like it could run almost mostly on geothermal, with some wind and solar. At least until the refugees arrive, from the lower 48.


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