1. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. CACTUS MOON EDUCATION, LLC www.cactusmooneducation.com ENERGY FROM THE EARTH GEOTHERMAL TECHNOLOGIES EDUCATION MODULE (GTH01PP)

2. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. INDEX Slide 1Title Slide Slide 2Index Slide 3 – 4 Geothermal Technologies Slide 5 – 7 Binary Cycle Geothermal Power Plant Slide 8 – 9 Flash-Steam Geothermal Power Plant Slide 10 – 11 Dry-Steam Geothermal Power Plant Slide 12 – 13 Hot Dry Rock Geothermal Power Plant Slide 14 – 15 Direct use Slide 16 – 17Geo-Exchange

3. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Geothermal Technologies - 1 Geothermal Energy is the energy contained in the heat inside the earth. Where the earth’s tectonic plates meet and slide under/over each other there are opportunities for the heat contained at the center of the earth to rise and approach the earth’s surface. This can take place in the form of: Spectacular and devastating volcanoes Spectacular but relatively harmless geysers. (For example – Old Faithful) or Hardly noticeable warm or hot springs

4. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Geothermal Technologies - 2 The presence of any of the above is a good indication of the proximity of a geothermal energy source. Drilling a hole into the earth in these locations – a geothermal production well - can very often allow us to tap into the geothermal reservoir and use the heat to produce electricity or for some other process. There are different technologies used to produce electricity depending on the temperature of the geothermal resource.

5. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Binary Cycle Geothermal Power Plant - 1 A binary geothermal power plant uses the relatively low temperature - 300° F – brine found in shallow geothermal reservoirs. The hot brine is pumped out of the “production well” and into the vaporizer where heat from the brine is transferred to a fluid with a low boiling point such as pentane (Pentane boils at 85° F). The pentane vapor powers the turbine/generator which produces electricity.

6. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Binary Cycle Geothermal Power Plant - 2 The vapor is then condensed back into a liquid to be re- vaporized in the vaporizer. The geothermal brine that was used to vaporize the pentane is re-injected into the earth in an “injection” well. Re-inserting the heat depleted liquid into the geothermal reservoir extends the life of the geothermal resource.

7. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Binary Cycle Geothermal Power Plant Geothermally heated brine is pumped out of the production well and into the vaporizer. 1 1 Heat from the brine is transferred to a liquid that has a low boiling point such as pentane. 2 2 The vaporized pentane powers a turbine/generator which produces electricity. 3 3 The pentane vapor is then condensed back into a liquid – ready to be returned to the vaporizer. 4 4 The geothermal brine that gave its heat in the vaporizer is re-injected into the earth to help extend the life of the geothermal resource. 5 5

8. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Flash-Steam Geothermal Power Plant Sometimes the temperature of the geothermal water is higher than the boiling point of water but the high pressure that the water is subjected to under the earth prevents the water from actually boiling As the water is allowed to reach the earth’s surface, the pressure is reduced and the water can “flash” into steam. The steam can be used to power a turbine/generator and produce electricity. The used steam is condensed back into water which can be re-injected into the geothermal reservoir to help extend the life of the geothermal resource.

9. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Flash Steam Geothermal Power Plant High temperature geothermal water is allowed to flash into steam in the “flash drum”. 1 1 The steam is used to power a turbine/generator which produces electricity. 2 2 The steam exiting the turbine is condensed back into water. 3 3 The water is re-injected back into the geothermal reservoir to help extend the life of the geothermal resource. 44

10. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Dry-Steam Geothermal Power Plant An even hotter geothermal resource can actually produce steam. With this type of geothermal source the steam is channeled through a “rock catcher” to remove solid debris before being used to power a turbine/generator. The steam exiting the turbine is condensed back into a liquid which is re-injected into the earth to help extend the life of the geothermal resource.

11. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Dry Steam Geothermal Power Plant The production well channels geothermally produced steam through a rock catcher. 1 1 The steam is then used to power a turbine/generator which produces electricity. 2 2 The steam exiting the turbine is condensed back into water. 3 3 The water is re-injected back into the geothermal reservoir to help extend the life of the geothermal resource. 4 4

12. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Hot Dry Rock Geothermal Power Plant Not all geothermal sources have “mobile” water to indicate their presence. A vast majority of the world’s accessible geothermal energy is found in rock that is hot but, essentially, dry. Water can be injected into the hot-dry-rock to be heated by the geothermal heat energy and pumped back out of the earth to be used in binary cycle geothermal power plants. The water used to power the plant is re-injected into the earth to be heated and used again.

13. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Hot Dry Rock Geothermal Power Plant 1 1 Water is pumped at high pressure (typically greater than 5,000 psi) into the earth in an “injection well”. 2 2 The high pressure water creates a “fracture zone” of fractures and channels in the hot rock. 4 4 The geothermally heated water is passed through a heat exchanger where the heat energy is transferred to a secondary liquid. 6 The heat depleted water is re-injected into the earth to be heated and used again. 6 5 The heat in the secondary liquid can be used to power a Binary Cycle Geothermal Power Plant (see slides 5 – 7). 5 The water flows through the fracture zone, is heated by the hot rocks and is collected in a production well. 3 3

14. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Geothermal Direct Use Not all geothermal sources are hot enough to be used to generate electricity. In many cases hot, or warm, geothermally heated water can be accessed by a relatively shallow well and the warm water used for “direct use”. Direct use includes using the warm water for residential space heating or for commercial aquaculture applications. Any application where warmth is desirable, such as shrimp farming or tomato growing can use the heat from a low temperature geothermal resource as a source of warm energy.

15. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Geothermal Direct Use 1 A relatively shallow well can be drilled to access the warm water from a geothermal resource. 1 2 2 The water can be used to provide warmth for commercial enterprises such as shrimp farming or growing tomatoes or other “heat” needing crops.

16. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Geo-Exchange Ground Source Heat Pump Geoexchange is a different use of geo-energy that takes advantage of the relatively constant temperature of the earth rather than the extreme temperatures associated with release of geothermal energy from tectonic plate activity. A conventional heat pump uses the ambient outside air temperature to help cool buildings in the Summer and help heat buildings in the Winter. In the Summer it becomes more difficult to “dump” the building extracted heat into the ever increasingly hot outside air. In the Winter it becomes more difficult to “extract” heat for the building from the ever decreasingly cold outside air. A ground source heat pump (geoexchange) system makes dumping heat into, and extracting heat from, the relatively constant temperature earth a much easier option.

17. __________________________ © Cactus Moon Education, LLC. Cactus Moon Education, LLC. Geo-Exchange Ground Source Heat Pump 1 A ground source heat pump consists of heat transfer coils that are buried in horizontal troughs or vertically drilled holes. 1 2 2 In the summer, the “cool” temperature of the earth can be used as a “heat dump” for the building heat pump in its cooling mode. 3 In the winter, the “warm” temperature of the earth can be used as a “heat source” for the building heat pump in its heating mode. 3