Environmental Physics PHYS 1149
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This 24 page Class Notes was uploaded by Maudie Larkin on Monday October 12, 2015. The Class Notes belongs to PHYS 1149 at Georgia Southern University taught by Anand Balaraman in Fall. Since its upload, it has received 51 views. For similar materials see /class/222053/phys-1149-georgia-southern-university in Physics 2 at Georgia Southern University.
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Date Created: 10/12/15
Chapter 8 Energy from Earth and Moon Solar Reflected flow sunlight 31 Infrared radiation 69 Tidal flow Tidal energy 00017 Energy of winds and currems Geothermal 0008 flow 0025 Photosynthesis 008 FIGURE 108 Energy Environment and Climate Copyright WiW Norton amp Company 2008 81 The Geothermal Resource Geothermal energy refers to energy that 53 comes from the interior of the planet 2500 K a 42700 km 135 GF aei l 2890 lzm 1500 4 000 K Most of the energy inside the planet comes from radioactive decay i v of elements like uranium thorium and potassium 6370 km 360 GPa 55004 000 K 81 The Geothermal Resource 39 Geothermal heat supplies only about 002 percent of the energy reaching Earth s surface but in a few localized regions the geothermal resource is significant 90 180 90 0 90 Latitude 90 180 90 0 90 Longitude FIGURE 801 Energy Environment and Climate Copyright WW Norton amp Company 2008 81 The Geothermal Resource Regions with some of the greatest geothermal energy potential are located along geologic plate boundaries gray lines and close to active volcanoes dots FIG URE 8 02 Energy Environment and Climate Copyright WW Norton amp Company 2008 81 The Geothermal Resource Geothermal gradient in the continental United States Note the preponderance of geothermal resources in the western states 82 Geothermal Energy Technology Geothermal resources range from Shallow ground Hot water and rock several kilometers below the Earth s surface Extremely hot molten rock called magma 82 Geothermal Energy Technology l Technologies for extracting geothermal energy include Direct use of geothermal heat Electric power generation FlG URE 8 04 Energy Environment and Climate Copyright WW Norton amp Company 2008 82 Geothermal Energy Technology Geothermal hot water carried through tubing installed in city sidewalks melts snow from walkways in Kla math Falls Oregon Snow melting 02 Greenhouses 14 Industry 5 Aquaculture 34 Resorts and spas 29 lt Heating of buildings 18 FIGURE 805 Energy Environment and Climate Copyright WW Norton amp Company 2008 82 Geothermal Energy Technology Direct uses of geothermal energy in the United States 82 Geothermal Energy Technology Electricity out 39 Turbine Generator r Condenser l 4 x l l Steam Rechag water Energy Environmen Ima e npyrighl o w w Norton 8 Co any zoos In a vapor dominated system steam wells up directly from the ground and is used to turn a turbine The spent steam is sent through a condenser and the condensed water is pumped back into the ground Electricity out 82 Geothermal Energy Technology Generator ep l l Recharge water l Condenser nergy Environment and Climate b E Copyright WW Norton amp Company 2008 FIGURE 809 82 Geothermal Energy Technology Heat exchanger A binary geothermal plant uses a closed loop with a separate working fluid which has a boiling point lower than water s The heat exchanger transfers energy from the warm geothermal water to the working fluid 83 Environmental Impacts of Geothermal Energy Pressurized geothermal fluids contain dissolved gases such as C02 NOX and H25 which escape to the atmosphere when fluids are brought to the surface Binary power plants greatly reduce the potential for land and water pollution 0 Typically geothermal power plants produce about 13 percent as much CO2 per unit electricity as do coal plants 83 Environmental Impacts of Geothermal Energy Advantages Disadvantages Requires no fuel Releases CO2 and other Lower emissions than for DOHUtantS into the fossil fueled power plants atmosphere Net vulnerable to Geothermal fluid used in fluctuations in fuel cost heat pumps is corrOSiVe Sustainable Some locations may m oraril quotcooldownquot Minimalland use te 390 V requirements Land subsidence from o scalable extraction of water 84 Heat Pumps Mechanical work or aYeclricity out Heal pumP a Burkd Mechanica work 01 plpea electricin in COOL Paw m Ermvy Emuuunwl m Dunn cam yucwi m u ommzuua b Energy Environmann and Climate Copyngm ww Manon 5 Company 2008 85 Tidal and Ocean Energy Only energy flow that originates as a high quality mechanical energy Gravitational field strength Manages gradient is what causes tides and not the gravitational field strength itself Sun s gravitational influence on Earth is 200 times stronger than Moon s But the gravitational field Earth strength of Moon changes more drastically with distance than Sunk Moon 85 Tidal and Ocean Energy Tidal energy originates from the Earthmoon system On an ideal oceancovered Earth there would be two tidal bulges on opposite sides of the planet Moon has an orbital period of 273 Tida39bu39ges days So its position shifts by about 13 degrees every day Moon s latitude also changes because its orbit is inclined Angular separation between Moon and Earth also affects the tidal amplitude Earth Amplitude is maximum under resonant conditions when Moon Earth and Sun align New Moon amp Full Moon Moon 85 Tidal and Ocean Energy Tidal energy is a limited resource that can provide a practical energy supply only in a few locations Shown on left is Canada s bay of Fundy in Nova Scotia which has the world s highest tides 17 m 85 Tidal and Ocean Energy Gravitational potential energy stored in tidal bulge gets dissipated due to drag viscosity eddies etc Result is the minute slowing of Earth s rotation and an increase in Moon s orbital radius 17 micro secyear ls60000 Yrs 1m4 MY 47 days month after 50 BY Sensitive measurements of Earth s spin time period indicates 3TW of power dissipated through tides Only 1 TW reaches shore lines of which 10 may be extracted at the most That makes 100 GW which is about 100 coal plants Nuclear plants 617 coal plants and 65 Nuclear plants functioning in US alone in 2007 560 new coal plants were built worldwide between 2002 and 2006 FIGURE 8 15 Energy Environment and Climate Copyright WWi Norton amp Company 2008 85 Tidal and Ocean Energy Locations of some of the world s highest tides with tide amplitude shown and estimated tidal power generation capacity listed for some sites Harnessing Tidal Energy Impound water during high tide and make the outgoing water turn a water wheel First tidal plant built in 1967at the LaRance river outlet in France Peak power output 240 MW 750 m long and impounds 17 Sqkm of water Bidirectional Environmental Impacts Reduces overall tidal flow affecting tide dependent biological activities Blocks the movement of marine organisms Estuaries harbor a rich diversity of marine life including commercially important fish species La Rance River Tidal Plant FIGURE 816 Energy Environment and Climate Copyright WW Norton amp Company 2008 85 Tidal and Ocean Energy Tidal energy is harnessed much in the same way as wind power by putting a large rotor in the way offluid flow and connecting the rotor to a generator
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