Overview of Contributors to the Cost of Geothermal Power Production

Transcription

1 Overview of Contributors to the Cost of Geothermal Power Production Greg Mines March 2006

2 Development of Geothermal Power Consists of successive phases including: Exploration Confirmation Site Development Well Field Construction Plant Construction Operation: power generation Risk is highest in the early phases. Cost is highest during the well field development and plant construction

3 Exploration and Confirmation Activities: Exploratory work to target resource; drill exploration wells; drill confirmation wells; flow test Factors influencing cost: New vs expansion of existing field Drilling (lithology, depth, temperature, etc.) Location (remoteness, topography, etc.) Size of resource Time delay to start of power generation

4 Well Field Development Factors influencing cost: Drilling lithology depth temperature rig availability Location Number of wells Project size Success rate Injection required? Well productivity Plant performance

5 Selection of Conversion System Flash Steam Higher temperature resources (>~175C) Plants tend to be larger (10-60 MW) Capital costs ~$1,000/kW (larger, higher temperature plants) Steamboat ~14 MW

6 Binary Conversion System

7 Binary Power Plants Wineagle: 2 units - ~0.7 MW Heber: 12 units - 33 MW Mammoth: 2 units 30 MW

8 Binary Plant Cost and Performance Factors Resource temperature generally used < 175C cost ($/kw) tend to increase with decreasing temperature efficiencies decrease required heat exchanger areas and/or flow rates increase performance decreases with decreasing temperature Size range: ~500 kw up to ~15 MW cost ($/kw) tend to decrease with increase size

9 Binary Plant Cost and Performance Factors Heat rejection ~90% 0f heat added is rejected evaporative vs sensible heat rejection Chemistry material of construction scale Working fluid Heat exchanger pinch point

10 Capital Costs for Air-Cooled Binary Plant GF: 150C, 5,000 gpm $3,000 Equipment installation mulitplier ~ 2.45 Other indirect plant costs: $3M $2,500 capital cost, $/kw $2,000 $1,500 equiment minimum equip field construction installed plant $1,000 $500 5,000 7,500 10,000 12,500 15,000 17,500 20,000 net power, kw

11 $6,000 $5,500 $5,000 Air-Cooled Binary Project Costs GF: 150C & 5,000 gpm Assumption #1 GF Pump Head ~500 ft Field Develop & Exploration ~$7M Assumption #2 GF Pump Head ~2,000 ft Field Develop & Exploration ~$20M capital cost, $/kw $4,500 $4,000 $3,500 $3,000 $2,500 $2,000 installed plant #1 Project #2 Project $1,500 5,000 7,500 10,000 12,500 15,000 17,500 20,000 net power, kw

12 Operating Costs Labor more significant for smaller plants automated vs manned operation Chemicals corrosion & scale inhibitors working fluid makeup Availability 95%+ Replacement wells & well work-over Submersible pump repair/replacement Royalties Annual O&M costs: 1-1 / 2 to 2-1 / 2 cents/kw-h

13 Acknowledgment This work was supported by the U.S. Department of Energy, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Geothermal Technology, under DOE Idaho Operations Office Contract DE-AC07-05ID14517.

14 Effect of Temperature on Plant Cost $3,000 Air-Cooled Binary Costs from 1996 EPRI Study, 50 MW plant installed plant cost $/kw $2,500 $2,000 $1,500 $1,000 cost cost w/o GF pumps $ resource temperature, o C

15 Effect of Size on Plant Cost $4,000 Air-Cooled Binary Plant Cost 1996 ERPI Study 150 o C Resource $3,500 Scale capital costs using Cost = Cost,ref* (Size/Size,ref)^n $3,000? n=1.0 n=0.9 n=0.8 cost $/kw $2,500? n=0.7 $2,000 $1,500 $1, plant size, MW

16 Summary Exploration and Well Field Development costs Drilling costs Well productivity Conversion System costs Resource temperature Type of conversion system Performance and cost tradeoff Plant size Operating & Maintenance cost Labor Conversion system Self-flowing vs pumped wells

17 Air-Cooled Binary Power Plant Capital Cost Distribution construction labor 21% equipment 41% fixed indirect 12% taxes & freight 5% civil & steel 6% piping 6% electrical & instrumentation 9%

18 Cost of Power Estimate Air Cooled Binary 150C, LCOE ~$0.085 per kw-h Plant O&M 15% Contingency 4% Royalty 3% Field O&M 4% Exploration & Well Field Development 19% - Estimate made with GETEM (Geothermal Electricity Technology Evaluation Model) - DOE Analysis Tool Power Plant 55% - Estimate does not reflect the costs for current commerical power generation. The scenario depicted by the estimate provides a basis for DOE to asses the impact of technology improvements.