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 – 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

If left unchecked…

If checked…

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rods Fuel rods are bundled with neutron-absorbing control rods Control rods inserted into reactor to slow reaction--withdrawn to speed reaction Uranium fuel pellets and fuel rod.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

NPP Layout

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 Alternatives

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