Geothermal4.5-billion-year-old reactor. Still running.
The earth is a nuclear reactor. A few kilometers down, it is hot enough to make steam — or, at shallow depth, stable enough to heat and cool a house with a ground loop.
Step through the entire flow.
Each step animates what is happening at that moment — click anywhere on the left to jump, or press play to watch the whole sequence.
Earth Heat
Radioactive decay in the mantle + residual formation heat. The earth’s core runs at ~5,200°C. Temperature rises about 25°C per km of depth.
Side by side with its competition.
| Technology | LCOE ($/MWh) | Capacity Factor | Lifespan (yr) | CO₂ (g/kWh) |
|---|---|---|---|---|
| Geothermal (flash) | 75 | 92% | 40 | 38 |
| Solar PV (utility) | 35 | 24% | 30 | 48 |
| Wind (Onshore) | 40 | 42% | 25 | 11 |
| Nuclear | 180 | 92% | 60 | 12 |
What's great. What's not. What critics say and whether they're right.
- 90%+ capacity factor — matches nuclear for firm baseload
- Tiny land footprint per MW
- Residential GSHPs cut HVAC energy use by 50–70%
- Site-specific — best resources in volcanic zones (Iceland, western US, East Africa)
- Drilling is expensive; EGS still maturing
- Upfront cost of residential GSHP is 2–3× air-source heat pump
- "Causes earthquakes" — only EGS with aggressive fracturing; standard hydrothermal plants rarely do.
- "Releases CO₂" — flash plants vent some geologic CO₂; still ~20× cleaner than gas.
Geothermal is the renewable baseload the grid has been missing. EGS could make it universal. Residential GSHPs are the most efficient climate system money can buy.
The research that will change this page in two years.
Next-gen EGS (Fervo, Eavor)
Oil-and-gas drilling tech applied to hot dry rock — making geothermal viable far outside traditional zones.
Superhot rock
Drilling to 400°C+ supercritical zones — 5–10× the power density of conventional geothermal.
See what others built
Community-submitted systems using this technology — budget, location, equipment list, lessons learned.
Plan your system
Step through the configurator — we size panels, inverter, and batteries based on your actual usage.
Curated gear list
Editor picks and best-value products, all with transparent affiliate disclosure.