Energy System Research and Testing (Conversion) Activities at NREL

1. Energy System Research and Testing (Conversion) Activities at NREL Gerry Nix March 20, 2003

2. Goal: Reduce Cost of Geothermal Electricity by at Least 1¢/kWh • Make the Plant Less Costly – Reduce Investment • Make the Plant Perform Better – Higher Efficiency, Greater Output • Make the Plant More Robust – Harder to Break • Make the Plant Easier to Operate – Reduce Costs via Automation and Instrumentation • Make the Plant Easier to Maintain – Better Materials and Designs Time Frame is in the Next 5 to 7 years for Implementation

3. Cost Reduction Targets • Binary Plants – Better Cycles (NREL, INEEL) • Enhanced Heat Transfer (NREL, INEEL) • Better Materials (NREL, BNL, INEEL) • Innovative Components (NREL, INEEL) • Better Instruments (INEEL, BNL) • Additional Revenues (BNL, LLNL)

4. Low-Temp Resources are More Common • 83% of the sites require binary plants (also, EGS/HDR will most likely need binary plants) • And 50% of the available energy is below temperatures requiring binary plants (170C) Frequency of occurrence and energy of hydrothermal convection systems identified by the USGS in 1978

5. Better Materials Polymer corrosion barrier coatings: • Prevent corrosion of geothermal plant equipment • Reduce maintenance expenses Steam vent at Cove Fort after 5 years of use Approach is to use inexpensive coatings with special properties on inexpensive base materials, with performance equivalent to exotic alloys

6. Extensive Field Testing (Mammoth, Cove Fort, CalEnergy)

7. Large Life Cycle Cost Savings

8. New Plant Built for PPS Business Perfected Electrostatic Application R&D 100, FLC Awards Collaboration with Curran, Int.

9. Future Work • Perform Long-Term Testing of Operating Equipment • Evaluate at Temperatures to 350°C • Expand Number of Test Sites and Partners • Test New, Thin Coating for Finned Tubing Exposed to Brine Spray

10. Why Improve Heat Rejection? • 90% of geothermal heat is rejected; condensers make up 20-30% of plant cost • Plant power will increase 1% for every1ºF drop in condenser outlet temperature • Output of air-cooled plant can drop more than 50% in summer, when electricity is highly valued • Water cooling can greatly reduce reservoir pressure (The Geysers) • Western states face water shortages – air cooling most likely required for new plants, including EGS and HDR

11. Air-Cooled Condenser Research Transpired and Tabbed Fins • Innovative designs • Increase performance by 30% • CRADA with manufacturer (SRC) Bottom line: Improved heat transfer reduces heat exchange area, and can reduce cost of electricity by 0.5 cents/kWh

12. Advanced Fins ITS Test Results Latest tab fin shows about 40% more heat transfer at the Same fan power with only 11% reduction in air flow, plan is To fabricate prototype and test at ITS

13. Fin-on-Plate Air-Cooled Condenser Test Setup

14. Fin-on-Plate Condenser, 36% higher heat transfer coefficient for the same pressure drop • Potential Industry Partners for Manufacturing; Linde, GEA Rainey, API Heat Transfer • Carry out field testing in collaboration with Exergy • Work with Experts in HX area (Prof. Ken Bell) • Collaboration with HTRI

15. Evaporative Enhancement of Air-Cooled Condensers - Measurements at Mammoth Munters increased net power output 62% (800 kW to 1,300 kW At 78°F ambient

16. Summary of Heat Rejection R&D Benefits • Increasing heat transfer on air and tube sides 30% can reduce electricity cost by 0.5 ¢/kWh • Evaporative enhancement and trim condenser concepts can potentially double output of air-cooled plants on summer days; payback for retrofit can be < 3 years depending on water and electricity costs

17. Innovative Components - Separators • Separators disengage solids and liquids from vapor. • They may also be used to separate NC gases. • Poor performance results in costly damage to turbo-machinery. • An industry-wide assessment of separators is needed to reduce O&M costs. • NREL brings advanced tools such as CFD (computational fluid dynamics) to industry • Partnership with Two-Phase Engineering

18. Well Test Plume Path lines

19. Separator in Operation

20. “DIRECT USE” - Applications Other Than Generating Electricity at Temperatures Under 250°F • Heating and Cooling • Aquaculture • Industrial Process Heat • Agricultural Process Heat • Spas, Pools and Bathing • Two Activities: • Direct Use Field Verification Projects • Direct Use Technical Support, Testing and Evaluation, OIT and WSU OIT: web hits: 2,000,000+ , in-person or phone assistance requests: 2000+

21. Direct Use Projects

22. Small Scale Field Verification Plants • Kalina Cycle – Plant to be built via Exergy to provide cost and performance data, support to DOE-GO • Mixed Working Fluid Binary Plant – Evaluation underway (Power Engineers) of a potential plant at Empire to provide cost and performance data • DOE assumes a significant portion of the risk

23. Geothermal Communications • Objective: • - Educate all stakeholder groups about geothermal energy, and- Convey the mainstream potential of this exciting technology Quarterly GRC Bulletin Inserts – industry audience Geothermal Today – all audiences

24. GPW State Posters GPW Native American Poster GPW State Fact Sheets – GPW stakeholder audience Web Sites Exhibits and Displays

25. NREL ESR&T Summary • It is Possible to Reduce COE by 1¢/kWh • Opportunities Exist for Quick Returns, 5 to 7 yrs to Implementation • Program is on the Way to Success, ala Direct Contact Condenser, PPS • All Activities are in Partnership with Industry • Proper Technical Areas are Targeted • Cost-Effective R&D Underway, guided by Extensive Systems Analyses • Promoting Direct Use is Important