Cost and Supply of Geothermal Power Susan Petty Black Mountain Technology

The Geothermal Resource Base USGS Circular 790 Released in 1979 Based on data from 1950’s-1978 Bonneville Power Authority Pacific Northwest only More detail for Northwest resources State Geothermal Resource Maps All states with geothermal resources Maps don’t evaluate resource potential

US Geothermal Resource Estimates USGS Circular 790 Estimates recoverable heat and potential power output Identifies resources on basis of surface manifestations 23,000 MWe from identified hydrothermal resources No assumptions about cost to produce power Enhancing permeability of identified resources a possibility Does not include hot dry rock Cuts off electric power generation at 150 °C

US Geothermal Resource Estimates BPA Northwest Resource Evaluation More detailed estimates for Washington, Oregon, Idaho and Montana Adds ~3500 MWe to USGS estimates for area Does not rely solely on presence of hot springs Considers cost in ranking resources for development

Other Geothermal Resource Data State geothermal resource maps Currently being updated by INL and some state geological surveys or universities Includes areas of high heat flow, surface manifestations and wells Geothermal Map of the US Recently updated Based on heat flow calculated from shallow and deep well temperature measurements Data available on web Thermal Springs Map of the US Springs with measured temperatures above regional groundwater temperature USGS Updated Basin and Range Temperature Gradient Database Now available on web from 425/webmaps/home.html. 425/webmaps/home.html Includes data from industry exploration

State Geothermal Resources Map - Utah

Utah Geothermal Resource Map - INEL

Geothermal Map of North America Detail of Utah

Temperatures at Depth for Continental US

Temperature at 6 km With depth to bedrock

Resource From Heat Mining Area in Utah that is above 240 °C at 6 km Total heat in place converted to electricity - 136,000 MWe for 1000 years Recoverable heat at 20% recovery – 27,000 MWe

Thermal Spring Map - Western US

Thermal Spring Map - Utah

Great Basin Geothermal Gradient Map

Cost of Geothermal Power Sandia – Petty, et al, Impact of Technology on Cost of Geothermal Power EPRI – Brugman, et al, Next Generation Geothermal Power Plants Renewable Northwest Project: Geothermal Power Resource CapitalCost ($US1999/kW) Geothermal$1,150–$3,000 Hydropower 27 $735–$4,778 Coal 28 $1,070–$1,410 Nuclear 29 $1,500–$4,000

Modeling Cost of Geothermal Power IM-GEO – Impact of Technology on Cost of Geothermal Power – Completed 1990, Updated – 1994 Used to build supply curves – 1992 Input for NEMS modeling by EIA EIA currently using this study escalated to current $ GETEM – Geothermal Energy Technology Enhancement Model In Beta testing Based on drilling costs from Sandia study 2004 Plant capital costs from reports by Ormat and Power Engineers and on EPRI 1996 study.

Modeling Data Requirements Resource Data Temperature Depth Flow per well Size of resource Temperature/Pressure decline rate Drilling difficulty – geology Exploration success rate Confirmation success rate Plant Data Binary or Flash Size of plant Number of units Binary or flash Pumped or Self Flow O&M as % of cost Economic Data Fixed Charge Rate Utilization Factor % Contingency %

Cost Modeling Results Binary Basin and Range Shallow Wells– 5000 ft wells, 150°C, 2000 gpm, Basin and Range drilling, Air-cooled binary plant, pumped wells

Break Down of Geothermal Power Cost Binary Basin and Range Shallow Wells – 2000 ft wells, 150°C, 2000 gpm, Basin and Range drilling, Air-cooled binary plant, pumped wells

Cost Modeling Results Binary Base Case – 5000 ft wells, 150°C, 2000 gpm, Basin and Range drilling, Air-cooled binary plant, pumped wells

Break Down of Geothermal Power Cost Binary Base Case – 5000 ft wells, 150°C, 2000 gpm, Basin and Range drilling, Air-cooled binary plant, pumped wells

Cost Modeling Results Flash Base Case – 8000 ft wells, 200°C, 500K lb/hr, Basin and Range drilling, Dual Flash plant

Break Down of Geothermal Power Cost Flash Base Case – 8000 ft wells, 200°C, 500K lb/hr, Basin and Range drilling, Dual Flash plant

Cost Modeling Results EGS High Temperature Case - 240°C at 6 km, pumped wells, 395 gpm

Cost Modeling Results EGS High Temperature Case - 240°C at 6 km, pumped wells, 510 gpm with technology improvement

Break Down of Geothermal Power Cost EGS High Temperature Case - 240°C at 6 km, pumped wells, 510 gpm, with technology improvement