Enhanced Geothermal Systems (EGS) could unlock geothermal power almost anywhere on Earth. Instead of relying on natural steam reservoirs, EGS injects water into hot dry rock at depth. This guide covers the technology, pilot projects, and commercial pathway.
The basic concept
Deep underground, rock temperature rises with depth. In many regions the rock is hot enough to produce power but there is no natural water flow. EGS drills two or more wells to depth, creates or enhances rock fractures, and circulates water: injection well pushes water down; production well brings hot water up; power plant generates electricity.
What is different from conventional geothermal
| Aspect | Conventional | EGS |
|---|---|---|
| Water source | Natural reservoir | Injected from surface |
| Rock permeability | Natural fracture network | Created or enhanced |
| Geographic range | Tectonic boundaries | Almost anywhere |
| Drilling depth | 2 to 4 km typical | 4 to 8 km |
| Cost | USD 60 to 100 per MWh | USD 100 to 200 per MWh currently |
How EGS works step by step
- Drill injection well to hot rock formation.
- Enhance fracture network via hydraulic stimulation.
- Drill production well intersecting stimulated zone.
- Inject cold water at high pressure.
- Water heats as it flows through fractures.
- Hot water returns via production well.
- Surface power plant (flash or binary) generates.
- Cooled water reinjected.
Notable pilot projects
| Project | Location | Notes |
|---|---|---|
| Fervo Nevada | US Nevada | 3.5 MW pilot commissioned |
| Fervo Utah | US Utah (Cape Station) | 400 MW under construction |
| Eavor Alberta | Canada | Closed loop demonstration |
| Soultz sous Forets | France | Long running EGS pilot |
| Pohang | South Korea | Ceased after 2017 induced seismicity |
| Cornish geothermal | UK Cornwall | Pilot heat plus power |
Technical challenges
- Drilling deep in hard hot rock.
- Creating adequate fracture permeability.
- Managing water losses to formation.
- Preventing induced seismicity.
- Well casing at high temperature and pressure.
- Long term reservoir sustainability.
Induced seismicity
The Fervo Energy story
Fervo Energy has been the most commercially advanced EGS developer. Their Nevada project demonstrated production; Utah Cape Station scaling up to hundreds of MW. Uses oil and gas horizontal drilling techniques adapted to hot rock.
Eavor closed loop
Eavor uses a different EGS approach: closed loop where water circulates in sealed pipes through hot rock. No fracturing required; no induced seismicity risk. Different tradeoffs in flow rates and depth economics.
Cost trajectory
Policy support
US Inflation Reduction Act tax credits apply to geothermal including EGS. US DOE has EGS deployment target of 90 GW by 2050. National labs and industry partnerships driving R and D.
Global EGS potential
Role in decarbonisation
EGS provides base load renewable generation that complements variable solar and wind. Particularly valuable in regions without existing hydro or geothermal.
Future outlook
- Fervo Utah project commissioning at scale.
- Additional Fervo projects in Nevada and Utah.
- Eavor commercial project deployment.
- European EGS demonstrations.
- Continued drilling technology improvements.
- Public acceptance framework development.
Frequently asked questions
Is EGS commercial?
Emerging. First commercial scale projects under construction.
Can EGS work anywhere?
Almost. Requires drilling to hot rock at depth.
How deep?
4 to 8 km typical.
Is it safe?
Modern projects with conservative protocols yes.
What is induced seismicity?
Small earthquakes triggered by fluid injection.
How large can EGS be?
Individual projects tens to hundreds of MW.
How much water does it use?
Significant. Water availability affects siting.
Is Fervo the leader?
Most commercially advanced.
What is closed loop EGS?
Water in sealed pipes; no fracturing. Eavor is main developer.
Where can I read more?
US DOE Geothermal Technologies Office, Fervo, Eavor, published journals.
Summary
Enhanced Geothermal Systems could unlock base load renewable generation almost anywhere on Earth. Technology is commercialising with Fervo Energy and Eavor leading. Cost currently high but falling. Public acceptance depends on managing induced seismicity risk. If EGS reaches commercial scale in the coming decade, it becomes a major renewable option for decarbonising grids.
Next reading
- Geothermal energy explained
- Geothermal countries lead
- How geothermal power plants work
- Browse the UtilityRadar directory
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