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• Control rods inserted into reactor to slow reaction--withdrawn to speed reaction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