It has been a pivotal year for the geothermal sector. Innovator Fervo Energy demonstrated a 70% reduction in drilling time at its campaign in Utah, a significant breakthrough for the industry that has been mainly held back by high project risks and high drilling costs.

Drilling costs can account for up to 75% of all project costs, as most of the geothermal drilling is done with big rotary rigs on loan from large oil and gas service companies at day rates. Any delays or non-productive time (NPT) costs additional revenue for the project developer.

The lack of subsurface data and high risks associated with drilling are the key reasons why geothermal projects fail and why geothermal power has been limited to regions with high enthalpy, such as Indonesia or Iceland. High enthalpy regions typically also have a high geothermal gradient, close to tectonic plates, so developers do not have to drill deep to encounter temperatures of 150 ° — high enough for power production.

Everywhere, in low enthalpy environments, temperatures increase at a rate of around 25° per kilometer.  Developers would have to drill at least 6KM subsurface to reach temperatures high enough for power production in low enthalpy environments but reaching lower temperatures of up to 75° can already go a long way in decarbonizing district heating and some industrial heating processes.

In addition to Fervo’s success, UTAH Forge, a field laboratory for enhanced geothermal drilling, has been able to reach similar rates of penetration (RoPs) over the last few years. Faster RoPs have been made possible by replacing tungsten carbide drill bits with polycrystalline diamond drill bits, which are more durable, and directional drilling. But there is still further scope for cost reduction and even faster drilling speeds.  

Don’t Have to Dig Deep

According to Eurostat, 30% of Europe used natural gas for space heating in 2022, and this figure is even higher in Eastern Europe. The Ukraine war sent natural gas prices skyrocketing and brought home the realization that Europe needs to wean itself off natural gas. In 2022, the installation of heat pumps in Europe jumped by 38% and the demand is increasing.

The jump in demand for shallow geothermal or ground-source geothermal heat is helping to derisk the geothermal drilling space. It has historically been difficult for developers of new geothermal drilling technology to stay afloat amid competition from oil and gas service companies, high project risks, and consequently less available venture capital.  Even when doing research for this project, the author came across several geothermal drilling companies that seem to have defaulted over the last few years.

However, heat offtake from shallow geothermal space gives new geothermal drilling developers the revenue required to derisk and build out their technology. In Finland, Geomachine, a company focused on soil surveys, came out with their GM2000 down-the-hole (DTH) hammer drilling machine that is fully automated and modular, cutting down on the staffing costs or manual data manipulation.

Canopus Drilling Solutions will test and commercialize its steel shot drilling solutions in shallow depths of up to 500 meters for two years before leveraging the same technology in ultradeep geothermal drilling. Canopus uses a modified polycrystalline diamond cutter (PDC) drill bit alongside high-pressure jets containing steel shot particles, reducing the wear and tear on the PDC drill bit. To counter the potential pressure drop at the bottom of the wellbore, Canopus adds up to 300PSI of pressure on the wellhead.

The Pot of Gold at the End of the Rainbow

In the U.S., industrial heat below 165° contributes to 3.5% of all U.S. energy-related CO₂ emissions, so unlocking some of that low-temperature heat will go a long way in decarbonizing industrial heat and district heating. However, with power demand forecast to double by 2040 and demand for net-zero power heating up, geothermal power is the real prize.

Fervo, Eavor and Sage Geosystems target hot dry rock formations, opening geothermal power up to geographies where underground reservoirs for heat/steam circulation are not readily available. Fervo plans to inject fluid, which will then be used to circulate heat that Fervo can use for power production. UTAH Forge in May successfully showed stimulating fluid flow and energy transfer from an Enhanced Geothermal Systems (EGS) reservoir in hot dry granite, further proving Fervo’s concept.

Start-up, Eavor, will drill an injection well and production well to depths of >7KM and then connect them with multiple laterals forming a radiator design. Eavor will then introduce its own working fluid in the closed-loop system. The working fluid circulates through a wellbore, extracting heat from the geothermal reservoir but doesn’t interact directly with the rock formations. This design requires extremely accurate drilling, as one lateral needs to be effectively drilled into another. There are very few survey tools that can accurately help detect laterals 7KM subsurface, as high temperatures reduce the effectiveness of measuring tools and electronics.

Start-up, Hephae, has developed a measurement-while-drilling (MWD) tool that operates at high temperatures of up to 210°. Meanwhile, Canopus boasts superior drilling accuracy. Both of these tools could go some way to offset problems with drilling accuracy at superdeep depths.