Energy ResourcesChapter 22Renewable•Solar–Direct• Photo-voltaic• Mirror focussing–Wind–Biomass– Hydroelectric•GeothermalNon-Renewable• Nuclear (U-fission)• Nuclear (Fusion)• Fossil Fuels–Oil– Natural Gas–Coal– Oil Shale & Tar SandU.S. Energy SourcesSolar• Direct– Solar-Thermal: Mirrors focus sunlight to boilwater.– Photo-Voltaic Cells: Direct conversion toelectricity.• Indirect–Wind– Hydro-electric– Biomass: Wood, grain, sugar, trash.Geothermal• Energy from Earth’s Internal Heat Engine• Geysers, CA Supplies San Francisco.• New Zealand, Iceland• Hot Dry RockFossil Fuels•Oil•Natural Gas•Coal• Oil Shale and Tar SandReserves and Resources• Reserves are the known amount of amineral in the ground that is exploitablewith current technology and under currenteconomic conditions.•“Resource” includes the reserves plusestimated undiscovered deposits.Origin of Fossil Fuels• Plants store energy from the sun byphotosynthesis.•CO2 + 2H2O = CH4 + 2O2• If biomass is buried before re-oxidation. thereduced carbon is preserved as fossil fuels.• Burial and compaction separates solid (coal),liquid (oil) and gaseous (gas) fractions.OriginofFossilFuelsOil and Gas• Liquid and solid fractions are mobile andcan be trapped by impermeable layers.• Only in sedimentary rock.• Most deposits of Paleozoic and Mesozoicorigin.• Search is to look for natural traps.Oil and Gas: The Future• World oil production expected to peak about2015.• Gas production will peak ~ 15 years later.• Price will increase sharply as production peaks.• Price will affect size of resource.Oil Shale and Tar Sand• Reserves nearly equal total of oil and gas• Colorado and Utah have large deposits ofoil shale in Tertiary rocks.• Alberta, Canada has large deposits of tarsands.Coal• Lignite (Peat)• Sub-bituminous coal• Bituminous coal• Anthracite (Metamorphic)Coal• Reserves are very large (~10 times that ofoil and gas).• Exploitation may depend on technology to“scrub” CO2.Scrub CO2?•Liquify CO2 and put on ocean bottom.•Mg2SiO4 + 2CO2 = 2MgCO3 + SiO2• olivine + carbon dioxide = magnesite + quartz• Scrubbing would ~double price.Greenhouse Gases•CO2, CH4• Pass Visible light• Opaque to Infra red• Earth captures energy from sun but cannotre-emit• Causes warmingCarbon Dioxide• Colorless, odorless, tasteless, poisonous gas• Animal life cannot exist in >1% CO2• Plants love it.• Current level is about 370ppm.• Increases at about 1% per year.• Greenhouse gas.Nuclear - 235U fission•235U is less than 1% of natural Uranium.• Can be enriched to 3.3%.• US light-water reactors use water asmoderator and coolant.• Produces about ~16% of US electricity andabout 7% of total energy consumed.• No new reactors.• Size of energy resource is larger than coal.235 U Fission• US light-water reactor• Water is moderator• Moderator slowsneutrons for capture.• Fuel is UO2 enriched to3.3% 235U.• Fuel produces 3 milliontimes as much energy pergram as fossil fuel.235U Nuclear- Other• Canadian (Deuterium moderated)• High Temperature Gas-Cooled– Graphite moderated– Highly enriched fuel– Chernobyl & Fort St. VrainRadioactive Waste• About half of 235U is consumed.• Spent fuel rods contain 90Sr and 137Cs plustrans-uranics (Np, Pu, Am, Cm, etc).• Cs and Sr have 30 year half-lives.• TUs have up to 24,000 year half lives.• Spent fuel still produces ~900 W/Ton ofpower after 10 years.Geologic Host Rocks• Salt (Germany, France, WIPP)– High Thermal conductivity– Self-sealing (flows plastically)• Granite (Sweden)– Good thermal conductivity– Stable craton environment• Tuff (Yucca Mountain, Nevada)– It’s in Nevada.– It’s already contaminated.Geologic Host Rocks: HanfordFuture Technologies• Breeder (Convert 238U to Pu)–238U is 99%+ of natural U– Early attempts were unstable.•Fusion– Nuclear fusion of light elements H, He, Li– Near break-even point– Size of resource is inexhaustibly
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