1. Lily Halloway Sarah Douglass
Geothermal Energy
Lily Halloway
Sarah Douglass

2. Overview “Geo”: Earth “Thermal”: heat -Converting heat to electricity
-Accessed by drilling water or steam wells in a process similar to drilling for oil
-Steam from heat inside earth turns turbines to create electricity
-Usually near geological hot spots
-3 types: dry steam, flash steam, binary cycle

3. Dry Steam
-Steam from underground is accessed through pipes into the turbine/ generator unit
2 known underground sources of steam: Geysers in northern California and Yellowstone National Park

4. Flash Steam -Most common type of geothermal power plant
-Use geothermal reservoirs of water with temperatures greater than 360*F
-Hot water moves upward through wells by its own pressure
Water loses pressure and some of it boils to produce steam
Steam is used to move turbine

5. Binary Cycle -Operate on water at lower temperatures (225-370*F)
-Plants use heat from hot water to boil a working fluid, usually an organic compound with a low boiling point
-Working fluid is vaporized in a “heat exchanger” and used to turn a turbine
-Water is injected back into the ground to be reheated
-Water and working fluid kept separate so there are few emissions

7. Main Goal of Geothermal Power
To have a renewable power source.
To have a greener power source without the compromise of energy
To decrease pollution made by power/ energy sources

8. History of Geothermal Energy
-Many ancient groups such as the Native Americans, Romans, and the chinese used hot mineral springs for bathing, cooking, and heat.
-Although this concept is old, the industry for Geothermal energy is relatively new. For example, one of the first attempts to use this as a main power source, was initiated by a group of Italians who built an electric generator powered by the natural steam erupting from the earth in 1904.
-The first attempt of Geothermal Power in the United States was in 1922 at the Geysers Steam Field. Although this attempt failed due to corrosion of the pipes and other factors. Later, a smaller successful one was built in the same area.
-Today, electricity is produced from a geothermal power source in 21 countries including the United States.

9. Environmental Impacts
-No reports of water contamination, although this is possible with the contact with sulfur- and mineral- rich underground water
-Using geothermal fluids other than freshwater reduces the environmental impact
-Water must be re-injected into the Earth to maintain the volume in the underground reservoir
-Open-looped systems- has air emissions including hydrogen sulfide, carbon dioxide, ammonia, methane, and boron
-Close-looped systems- minimal air emissions

10. Environmental Impacts, continued
-Some plants produce mercury emissions
-Pumping water through earth can cause fractures in rock leading to earthquakes
-Emissions associated with construction and surrounding infrastructure of plants
CO2 emissions
Geothermal Coal
0.6-2 lbs of CO2 per kilowatt-hr lbs of CO2 per kilowatt-hr

11. Global Impacts
-CO2 emissions could increase global warming, but still better for the environment than coal
-As countries are able to produce their own electricity, they become less economically dependent on other countries

12. Mass Production, Delivery, and Use
-Usually geothermal energy plants are constructed in rural energy, which benefits rural communities that may otherwise have trouble accessing electricity
-Developing countries can use this source to improve infrastructure and preserve the cleanliness of the areas
-examples: Kenya, Caribbean Islands, Indonesia
-Developed countries are starting to facilitate geothermal projects

13. Geothermal Energy Pros Cons
-Environmentally friendly compared to gas or oil furnaces (no combustion).
-Efficient ( % compared to 90% of the best furnaces).
-No cost fluctuations determined by gas and oil prices
-30%-60% savings on heating and 25%-50% savings on cooling
-Not weather dependent like solar or wind power; geothermal heat pumps work year-round.
Cons
-High upfront costs with implementing geothermal energy. ($10,000-$20,000)
-Electricity is still needed to operate heat pumps.
-Geothermal energy using wells requires an incredible usage of water.
-Discharge into the Earth could include sulfur dioxide and silica (well pumps).
-Damage to underground loops (tree roots, rodents, etc.) can be difficult and costly to repair.
-Large scale geothermal power plants are dangerous to the Earth’s surface and location-centric.

14. Sources
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