Transmission Is Geothermal The Next Evolution In Energy Storage? - Sage Geosystems
Mar 3, 2026
Cindy Taff, CEO of Sage Geosystems and former Shell executive with 35 years in oil and gas, talks about applying drilling and subsurface know‑how to next‑gen geothermal. They discuss engineered hot‑rock reservoirs, an underground pressure‑based storage called EarthStore, fast, long‑duration dispatch, and why big tech and defense are already interested.
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Design Projects Around 200°C At 20,000 Feet
- Target sites with ~200°C at ≤20,000 feet to use off-the-shelf oil and gas drilling rigs and control costs.
- Western US, Gulf Coast, and some interior basins meet those depth/temperature economics; eastern US heat is deeper and costlier.
Per-Well Storage Scale And Duration Targets
- A single 9-5/8 or 10-inch well Earth Store yields ~3 MW with ~30,000 barrels cycled for 6+ hour discharge.
- Sage positions storage for longer-duration services, not competing with 2–4 hour lithium-ion batteries.
Very Fast Dispatch And No Cycling Degradation
- Earth Store dispatch is very fast because the high-pressure valve sits only a few feet from the Pelton turbine nozzle.
- Commissioning tests showed the turbine can spin up in under 60 seconds with no cycle degradation.