Geothermal Energy Heat flow from Earth’s Crust Radioactive decay of K,U,Th Intrusion of magma into crust Movement of tectonic plates

Power Generation >150ºC required, lower for direct heating Currently only Hydrothermal- water/steam US capacity-2930 MW ~90% capacity factor Efficiency 5-20% Little/no emissions

Geothermal Resources 13 million quads,130,000X current annual consumption Much less economically extractable Best prospects in Western US Only 11% resources exploited with current technology EGS has highest potential 100,000 MW achievable by 2050 1/10 current production

Enhanced Geothermal Systems Hot dry rocks Drill two wells, hydraulically fracture rock Circulate water Could sequester CO2

Past Field Studies 25 kg/s flow rate achieved, goal 80 kg/s Best to stimulate existing fractures 5 MW can be produced in each commercial scale well

Technical Challenges High drilling costs: largest expense, high temp, hard rocks Short Circuits-water loss, chemical additives only up to 175ºC Rock/water interactions Resource depletion Fracture Growth Better reservoir Models

Questions?