Concept 1 / 2
Geothermal Resource Fundamentals
Geothermal gradient: ~30°C per km depth (continental crust average)
- High-potential regions: Iceland, Italy, Turkey, western USA (~70–100°C/km)
- Germany: ~30°C/km
Temperature at depth:
T(depth) ≈ T_surface + gradient · depth
Example: 3 km deep in Germany:
T ≈ 10°C + 30°C/km · 3 km = 100°C
→ Good for district heating, not electricity
Minimum temperature for electricity generation: ~150°C
(ORC possible at >80°C, but Carnot efficiency too low below 150°C)
Key advantage over wind/solar:
- Baseload: Available 24/7, capacity factor >80%
- Not weather-dependent
- Fully dispatchable