1. Geothermal Heating and Cooling Applications Rachel Kerekgyarto

2. Geothermal Energy Thermal energy stored in the Earth Sources – Solar energy absorbed in Earth’s crust – Radioactive decay at the core of the Earth Clean, sustainable energy source

3. Geothermal Resources Three Classifications – Low Temperature: 40  F - 100  F Widespread Heat Pump Applications – Moderate Temperature: 100  F - 300  F Direct-Use Heating Applications – High Temperature: > 300  F Electricity Generation Focus: Low Temperature

4. Geothermal Heating Principles Conventional heating systems (furnaces or boilers) create heat Heat pumps transfer existing heat from one area to another Ground temperatures are more stable than air temperatures…Smaller Lift Ground serves as a… – Heat source in the winter – Heat sink in the summer

5. U.S. Ground Temperatures Range: 37  F - 77  F

6. Changes in Ground Temperature Seasonal ground temperature change decreases with depth Depths greater then 20 ft: constant ground temperature

7. Geothermal Heat Pump System Three Major Components – Ground Loop Piping System Circulates a fluid & serves as an underground heat exchanger – Heat Pump Uses refrigerant loop to convert heat into useable heat – Ductwork Distributes heat throughout building

8. Types of Ground Loops Open Loops – Open to environment – Circulate groundwater (or surface water) to the heat pump, then discharge the water Closed Loops – Sealed loop of pipe in the ground or a body of water – Continuously circulates a fluid to the heat pump

9. Open Loops Well Requirements – 1.5 – 3.0 gpm per ton of heating capacity Water Quality Concerns – Hardness, Acidity, Iron Water Discharge – Surface water – Drainage ditch – Recharge groundwater

10. Closed Loops - Horizontal Shallow Trenches – 4 – 6 ft deep Pipe Length – 500 ft of pipe per ton of heat pump capacity Land Area – 750 to 1500 ft 2 per ton

11. Closed Loops - Vertical Drilled Boreholes – Depths up to 250 ft Pipe Length – 300 ft of pipe per ton Land Area – 100 – 200 ft 2 per ton

12. Closed Loops - Slinky Greater heat transfer in a given volume of soil Compact or Extended Coils Horizontal Configuration – Uses 1/3 trench length of a 2-pipe loop Vertical configuration – Depths of 20 – 30 ft

13. Closed Loops – Lake Water Surface – ¼ - ½ acre Water Depth – Minimum 8 ft

14. Closed Loops Piping – HDPE Plastic Pipe – Joined by thermal fusion – Minimum 50 yr warranty

15. Closed Loops Ground Loop Fluids – Water: warm climates only – Antifreeze Solution Salts – Non-toxic, good heat transfer, BUT corrosive Glycols – Non-corrosive, fair heat transfer, BUT toxic & viscous Alcohols – Non-corrosive, fair heat transfer, BUT toxic & flammable Potassium Acetate – Non-toxic, non-corrosive, more efficient

16. Closed Loops - Geobag LDPE Plastic Bag – 60 ml thick Horizontal Configuration – Uses 1/5 trench length of a 2-pipe loop Undergoing Field Development

17. Closed Loop – Direct Expansion Direct Refrigerant Ground Loop – Higher Efficiency – Copper Piping Undergoing Field Development

18. The Heat Pump Refrigeration device that works backwards Heating Schematic

19. The Heat Pump Cooling Schematic Domestic Hot Water Heating

20. Refrigerant R-22, an HCFC ODP = 0.05 (Ozone Depletion Potential) – 5% of CFC-11&12 ODP Production Phase Out 2030 Alternatives – Blends of HFC’s – zero ODP

21. System Cost Comparison

22. Heat Pump Efficiency Coefficient of Performance: 3.0 - 4.0 – Produce 3 to 4 times the energy used 40% to 60% Energy Savings 2 – 8 year Payback on Initial Cost Utility Rebates – GHP’s reduce peak load

23. Operating Cost Comparison

24. Eliminating Emissions Galt House East Hotel – Louisville, Kentucky – Open Groundwater Loop (58 o F) – Annual Energy Savings: 5.6 mil kWh – Annual Emission Reductions 1.8 mil lb of CO 2 44,000 lb SO X 33,000 lb NO X

25. Conclusion Estimated 400,000 GHP Systems in U.S. – Increasing Popularity – Residential & Commercial Installations Advantages – High Efficiency – Reduce Emissions – Renewable Resource – Economical – Constant Availability