geologic resources: part 2. alternative energy types fossil fuels – limited supply alternative...
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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– 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• Control rods inserted into reactor to slow reaction--withdrawn to speed reaction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 energyas 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
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