Published on January 17, 2008
Renewable energy sources: Renewable energy sources Slide2: Estimates of depletable energy resources in the U.S. Numbers = how long it would last if all energy came from one source Resource recoverable recoverable and hoped for Coal 125 1300 Petroleum 5 50? Natural gas 5 50? Oil shale 0 2500 Conventional reactors 3 15 Breeder reactors 115 750 Fusion 106 to 109 Geothermal surface 0.2 60 deep rock 0 600 Slide3: Estimates of renewable energy Numbers = proportion of current U.S. energy needs that could be supplied for an indefinite period. Tidal energy 0.1 Organic Waste 0.1 Photosynthesis 0.23 Hydropower 0.14 Wind Power 5 Solar radiation 740 Slide4: Geothermal Heat near surface of the earth = geysers, volcanoes, hot springs Slide5: Use heat to make steam to turn turbine for electrical generation Note: deep hot waters are corrosive to best to inject clean water in a closed system and bring it back to the surface as steam. Slide6: In U.S., much done on public land = cheap Very little potential in east and mid west Slide7: World wide distribution of volcanos, hot springs, etc. Japan, Iceland,New Zealand big users of geothermal. Slide9: Although hot areas near surface are limited, the earth is hot everywhere if you go down far enough. Slide10: Bright idea!? – drill deep enough to find heat. Since rock is a poor conductor of heat, set off a big bomb to crack the rock and allow heat to move – then pump down water to make steam. Slide12: Hydropower = dams Not much used in world, why?? Slide13: Norway, Zambia, Ghana big users Slide15: Most unused hydropower in U.S. = Alaska, In World = Canada, Russia Problems with hydroelectric: Problems with hydroelectric Location = unused rivers are in extreme north or low population areas Competition with recreational uses (U.S.) and environmental concerns Hard to build dams in populated river valleys Siltation of dams – limited life. Slide17: Tidal Power In areas of large tides Anywhere – build offshore dam Slide18: Highest tides in the world = Bay of Fundy 16 meters = 48+ feet! Slide19: Tidal power anywhere No dam – but a turbine. Problems: Corrosion Navigation Appearance Amount of energy available is low Best tides are near poles – away from people. Slide20: Wind Power = wijnd farms Banning Pass Slide21: Best wind location = Aleutian Islands, why no wind development there? Slide22: Best U.S. localities Midwest, mountains And coastal areas. Slide24: Netherlands = coastal development Slide25: England = off shore Wind energy problems: Wind energy problems Location – near population center Bird migration – Visual Must be coupled with other sources of electricity. (intermittent supply) Slide28: Solar farm = big solar plants Slide31: At focal point = heat liquid – steam to turn turbine ‘hard’ vs ‘soft’ energy paths: ‘hard’ vs ‘soft’ energy paths Hard = Big plants Centralized production Soft = Decentralized units per household Slide35: Energy efficient house; wind power on roof. Solar panels for heat and electricity. Slide36: Solar electricity generation Slide37: Solar water heating solar air heating Solar house problems: Solar house problems The Los Angeles air = smog Retrofitting- very expensive Hard for big hotels, Walmarts, etc. Solar house economics: Solar house economics Add $16,000 to price of house Pay back - $1500 per year in energy costs 15 years to break even Federal tax incentive; 40% of investment can be written off. Discontinued in 1986 City of Claremont – solar energy ordinance. 60% of hot water – solar Exceptions for equivalent savings of energy = Colleges approach. Why not trust solar? Slide41: Electrical generation Switch from petroleum to coal and natural gas Why has hydroelectric declined? When did nuclear go up? Slide42: Note: drop in fusion, fission – why? drop in renewables, increase in fossil fuels.