Geothermal Energy The Geothermal Heat Pump

1. Geothermal Energy The Geothermal Heat Pump Frederick A. Kundell, Ph.D. Department of Chemistry Henson School of Science and Technology Salisbury University

2. Geothermal Energy Geothermal energy is thermal energy emitted from the earth. Generally, when oneconsiders geothermal energy one thinks of high temperature deposits.

3. Renner, Joel NREL Pix # 05424

4. J. Ruhle and Assoc.

5. Deposits at Geyser, California Pacific Gas & Electric NREL Pix # 00060

6. High temperature geothermal deposits are easily converted to electricity. Gretz, Warren NREL Pix # 00426

7. On the east coast geothermal investigations have centered on trapped bodies of water heated by nuclear decay in granite rock formations. The Atlantic Coastal Plane has been examined for blocks of granite and wells drilled to check the temperature of overlaying bodies of water.

9. The highest temperature found to date is 180oF at Crisfield, MD. Unfortunately, this temperature is too low for economical use. Nevertheless, geothermal does have great economic potential on the Delmarva Peninsula.

10. The Delmarva Peninsula is formed from overlain sand clay strata which can be easily and “inexpensively” drilled. This “thermal mass” is ideal for use as a heat source or heat sink for a groundwater-to-air or geothermal heat pump. This process is referred to as geo-exchange.

11. Older systems (open systems) used well water along with an injection well to flow groundwater through the heat pump. During the winter heat was extracted from the groundwater prior to injection and during the summer heat is added to the ground water.

12. The problem with open systems is that well water may be acidic or contain suspended or dissolved contaminates which can damage the unit. Do not use open systems on the Delmarva Peninsula!

13. Newer systems are, for the most part, closed loop systems. The fluid is pumped through plastic pipes which are inserted in wells or buried in trenches. The geothermal fluid exchanges heat with the surrounding earth. Either trenches or well can be used.

14. Jones, Robert R. NREL Pix # 07093

15. Jones, Robert R. NREL Pix # 07099

20. Barlean, John NREL Pix # 07252

21. Geo-exchange well system.

22. For maximum thermodynamic efficiency the heat exchange pipes should not be influenced by atmospheric temperature. Thus, the well configuration is more effective and less prone to damage.

23. Why the Higher Efficiency? Geothermal fluid, either from an open or closed loop system, will be warmer than the outside air during times when heat is required or colder than the outside air when cooling is needed. This makes the geothermal heat pump much more efficient than a conventional air-to-air heat pump.

24. 1st Law Type of Heat COP* Efficiency Electric Resistance 1 100% Air-to-air Heat Pump 2 200% Geothermal Heat Pump 4.5 450% * COP = Coefficient of Performance

25. Geothermal heat pumps are available for individual homes. Lundy, Ann S. NREL Pix # 07408

26. or large buildings Tundy, Ann NREL Pix # 06569

27. In a real sense the use of the well configuration geothermal heat pumps recycles heat. Heat is pumped into the ground during the summer to be extracted during the winter. Clip Art

28. Approximate Energy Costs Information

29. Energy Costs per 1 million BTU’s * Installation Costs much higher with about a seven year payback.

30. The End