Residential Geothermal Energy Use

1. Residential Geothermal Energy Use BY: ANA BRAR

2. What Is Geothermal Energy? • Heat from the earth • Can be found almost anywhere • Affordable and sustainable • Hot, molten magma found under the Earth’s crust • Heat is continuously produced – decaying radioactive materials (U and K) • 50,000 times more energy than all the oil and natural gas in the world within 10,000 m of the surface

3. More About Geothermal Energy • Areas with highest underground temperatures = active/geologically young volcanoes • Also when crust is thin and at plate boundaries • Ring of fire – Oregon, N. Nevada, California

4. How Geothermal Energy is GeneratedTechnique #1 • Tap into hydrothermal convections systems in which heated water rises to the surface • Three designs • Pulls water/steam, uses it, returns as warm water • 1: Steam goes directly through turbine then into a condenser where the steam is condensed into water

5. Technique # 2 • Very hot water is depressurized or “flashed” into steam • Used to drive turbine to generate electricity

6. Technique # 3 • Binary system • Hot water passes through a heat exchanger • Heats a second liquid (i.e. isobutane) in a closed loop • Isobutane boils at a lower temperature than water • More easily converted to steam to run the turbine

7. Deciding a Technique • Technique determined by the resource • If water comes out as steam, the first technique is easiest • More hot water resources than pure steam or high-temperature water sources • Most growth potential in heat exchanger system

8. Current Use • Largest geothermal system • The Geysers, CA - North of San Francisco • 26 power plants – 2,200 megawatts • Meets nearly 70% of the average electrical demand for California's North Coast region

9. Current Use in the U.S. • U.S. produces enough electricity for 2.4 million households • Not including contributions from geothermal heat pumps and direct heating uses • U.S. has about 3,000 MW of geothermal electricity connected to the grid • Represents 0.3 % of the world total electrical energy • 2007 - Accounted for 4% of renewable energy-based electricity consumption in the U.S. • https://publicaffairs.llnl.gov/news/energy/content/energy/energy_archive/energy_flow_2006/LLNL_US_Energy_2006.png • The U.S. continues to produce more geothermal electricity than any other country, comprising approximately 30 percent of the world total

11. Residential uses • Geothermal energy can be used for both heating and cooling purposes • Klamath Falls, OR and Boise, ID – geothermal water has been used to heat homes and buildings for over a century • Reno, NV – new houses • Iceland – more than 50% of energy from geothermal sources

12. Geothermal Energy Use in Homes • Called ground-source pumps • Constant year round temperature of 50°F that is just 5 to 10 feet underground • Air or antifreeze liquid is pumped through pipes underground • Summer – pipes move heat from the building and bring in cooler air • Winter – provide pre-warmed air and water http://earthcomfort.com/howitworks

13. Installation • 4 main ways geothermal system can be installed • Horizontal Straight Loop – most common, economical, 5 feet underground • Horizontal Coiled Loop - pipe is spread out in flattened, overlapping coils

14. Installation - continued • Vertical loops – buried deep in the ground, ideal for buildings that lack large areas of yard needed for the horizontal loops, more costly • Pond loops – use existing bodies of water on the property to extract energy

15. Environmental Benefits • Burns no fossil fuels • Renewable and sustainable form of energy • Study by the Environmental Protection Agency found that it’s 72% more efficient than electric heating and AC • Uses no flame and doesn’t release toxic fumes into the house

16. Financial Benefits • U.S. Dept. of Energy says that heat pumps can save a typical home hundreds of dollars in energy costs each year, with the system paying for itself in 2 to 10 years • Cost-competitive: 2–10 US cents/kWh • State and federal incentives under the American Recovery and Reinvestment Act of 2009 - one-time tax credit of 30 percent of the total investment

17. Geothermal Vs. Other Energy Forms • Geothermal Vs. Fossil Fuels • More eco-friendly • Geothermal: electricity is produced with an efficiency of 10–17% vs. 36-40% (fossil fuels) • Renewable: As long as we don't pump too much cold water down and cool the rocks too much • Geothermal Vs. Solar • Solar gives energy intermittently – only during the day and without clouds • Unpredictable

18. Drilling for water • Challenge of limiting heat loss as the water is pumped back up the hole • Water is hotter the deeper down the well is drilled

19. Disadvantages • Certain techniques (such as the one used in The Geysers, CA) loses 60-80% of the steam to the air, not reinserting it back underground • Hydrogen sulfide, arsenic, and minerals are released in the steam • Geothermal energy site may run out of steam for decades

20. Conclusion • Future uses • Holds promise for the future • Can supply continuous base power much like fossil fuels but without the harmful emissions • Cost for electricity from geothermal is decreasing

21. Works Cited • Geothermal Energy Association: http://www.geo-energy.org/aboutGE/currentUse.asp • Earth Comfort – Heating and Cooling: http://earthcomfort.com/howitworks • Geothermal energy technology and current status: An overview: www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6VMY • Union of Concerned Scientists: http://www.ucsusa.org/clean_energy/technology_and_impacts/energy_technologies/how-geothermal-energy-works.html