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Geologic Resources: Part 2. Alternative Energy Types. Fossil Fuels Limited supply Alternative energy—any alternative to fossil fuels Nuclear (non-renewable) Wind, solar, geothermal, hydroelectric. Nuclear Fuels. Nuclear fuels are any material that can be used to create nuclear energy
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Alternative Energy Types • Fossil Fuels • Limited supply • Alternative energy—any alternative to fossil fuels • Nuclear (non-renewable) • Wind, solar, geothermal, hydroelectric
Nuclear Fuels • Nuclear fuels are any material that can be used to create nuclear energy • Non-renewable • Most common nuclear fuels • Uranium-235 • Plutonium-239 Enriched Uranium Billet
A note on Uranium… • Naturally occurring uranium • Mix of isotopes • U-238, U-235, U-233 • Only .7% U-235 • Need 3% to be used as fuel • Enrichment—separation of the isotopes to get more U-235
Nuclear Fission and Energy Production • Nuclear fission • the “splitting” of an atom • U-235 commonly used • U-235 nucleus is bombarded by neutrons • Chain reaction
How to Control a Nuclear Reaction • Fuel pellets are contained in fuel rods • Fuel rods are bundled with neutron-absorbing control rods • Control rods inserted into reactor to slow reaction--withdrawn to speed reaction Uranium fuel pellets and fuel rod. Each pellet contains as much energy as one ton of coal
Nuclear Power Pros • Low fuel consumption • 3 kg/day vs 9000 tons/day for coal • Uranium fuel is more abundant than fossil fuels • If the world were to use nothing but nuclear power, reserves would last ~400 years vs 35 yrs for fossil fuels • Low air pollution • Compared to fossil fuels • Lowers dependence on foreign fuels
Nuclear Power Cons • 20 tons/yr waste • Every step of production • Waste is radioactive • 10k years or more to decay to safe levels of radioactivity • Minor mistakes can create serious public health hazards
Chernobyl • April 1986 • Did not create a nuclear explosion • Chain reaction got out of control-two explosions • Exposed reactor to air—graphite moderators burned • Plume of radioactive fallout into air—wind carried it over western soviet union, Europe, and eastern N. AM
Renewable Energy • Resources that are replenished as they are used—renewable • The “Big Four” • Solar • Wind • Geothermal • Hydroelectric
Solar Energy • <1% of global energy • Passive solar collection • South facing windows • Active solar collection • Moving parts to Distribute heat generated • Solar arrays
Pros and Cons of Solar Energy • Pros • No pollution • Quiet • Good for remote areas • Putting up solar panels cheaper than laying out cables for traditional transmission of electricity • Utilize existing space • Ex. Rooftops • Cons • High start up cost • diurnal • Weather/pollution effects • Current cell models are very inefficient
Wind Energy • Only 1.5% of global energy—steadily rising • Wind turbines use kinetic energy (energy of motion) from wind to generate electricity
Pros and Cons of Wind Energy • Pros • No pollution • Versatile • Can generate electricity for single homes or large numbers of homes • Do not consume anything aside from the materials used to create them • Cons • Unsightly • Noisy • Can be easily damaged in thunderstorms • Blades can hit birds that try to fly between them • Interference with migratory routes
Geothermal Energy • <1% of global energy • Energy extracted from the earth’s own subterranean heat • Natural, hot ground water can be used to generate electricity or to directly heat homes • Can also pump cool, surface water into earth to heat it
Pros and Cons of GE • Pros • Cheap (after initial costs) • No pollution • Can use its own electricity to power pumps—little need for exterior power sources • Reliable • Cons • High initial expense • Need to drill wells, install piping • Requires lots of space • Aesthetics • Geothermal power plants are ugly—plain and simple • Expensive to dig deep—near surface magma sources are somewhat rare except in certain places
Hydroelectric Energy • 19% of world’s energy • Dammed water is used to spin giant turbines– electricity is generated
Pros and Cons of HE • Pros • Low pollution generation • Reliable • Flood control • Recreation areas • Boating, fishing • Cons • Damming a river destroys local eco-systems • Fish migration • Flooding of river valleys • Disruption of river seasonal cycles • Material transported by river is stopped by dam • Expensive to build • A dam breach can flood downstream areas