Transcript Ana - final
Residential Geothermal Energy Use BY: ANA BRAR 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 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 How Geothermal Energy is Generated Technique #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 Technique # 2 Very hot water is depressurized or “flashed” into steam Used to drive turbine to generate electricity 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 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 hightemperature water sources • Most growth potential in heat exchanger system 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 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 energybased electricity consumption in the U.S. https://publicaffairs.llnl.gov/news/energy/content/e nergy/energy_archive/energy_flow_2006/LLNL_U S_Energy_2006.png The U.S. continues to produce more geothermal electricity than any other country, comprising approximately 30 percent of the world total 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 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 prewarmed air and water http://earthcomfort.com/howitworks 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 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 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 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 Geothermal Vs. Other Energy Forms Geothermal Vs. Fossil Geothermal Vs. Solar 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 Solar gives energy intermittently – only during the day and without clouds Unpredictable 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 Disadvantages Certain techniques (such as the one used in The Geysers, CA) loses 6080% 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 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 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=B 6VMY Union of Concerned Scientists: http://www.ucsusa.org/clean_energy/technology_and_im pacts/energy_technologies/how-geothermal-energyworks.html