Chapter 20: Nuclear Energy
Alternatives to Fossil Fuels 80% of the global energy comes from fossil fuels We need to switch to non-fossil fuel resources because They will run out They will become very expensive Petrodictatorships
Alternatives to Fossil Fuels
Alternatives to Fossil Fuels Alternatives have been developed Still remain more expensive since the TRUE cost of fossil fuels is not factored into the market price Technology not fully developed
Alternatives to Fossil Fuels Nuclear power, biomass energy, and hydropower are conventional alternatives Have less environmental impact than fossil fuels, but more than “new alterative” energy Best viewed as intermediates – bridge to all “new” renewable energy
Alternatives to Fossil Fuels Conventional alternatives provide some of our energy and much of our electricity
Nuclear Power Benefits Drawbacks No atmospheric pollutants “fuel” only needs to be added on a yearly or biyearly basis Drawbacks Radioactive waste disposal Accidents are rare, but can be VERY bad Uranium – the fuel – is nonrenewable
Nuclear Power France is often thought of as a leader in nuclear power since such a large % of their electricity is created by nuclear power plants
Nuclear Power - Fission Nuclear Energy – transforming the “strong nuclear force” (the force that holds protons and neutrons together in an atom) into thermal energy to turn a turbine and generator.
Nuclear Power - Fission
Nuclear Power – Fission Nuclear Power Plant – controlled chain reaction Nuclear Bomb – uncontrolled chain reaction
Nuclear Power – Enriched Uranium 99% of the uranium in the world is U-238, but this cannot sustain a chain reaction We use U-235 in our nuclear reactors. Fuel rods are made from uranium that has been enriched to 3% U-235
Nuclear Power – Generating Electricity
Nuclear Power – Generating Electricity A moderator (water or graphite) is used to slow the neutrons Control rods are used to soak up extra neutrons to slow down the chain reaction. They can be placed all the way down to stop the reaction
Nuclear Power – Breeder Reactors Benefits Use U-238 as the fuel Far more power, far less waste Drawbacks More dangerous – use liquid sodium More expensive Can be used to make plutonium for nuclear weapons
Nuclear Power – Breeder Reactors
Nuclear Power - Fusion
Nuclear Power - Fusion The process that goes on in our Sun. Must be done at very high temperatures and pressures in order to overcome the repulsion of the nuclei
Nuclear Power - Fusion
Nuclear Power - Fusion Still very theoretical – no commercial plants in use. Prototype being build in France (ITER)
Nuclear Power – Cleaner than Fossil Fuels Little to no air pollutant and greenhouse gas emissions Less fuel needed means less mining
Nuclear Power – small risk/large accidents Three Mile Island – Pennsylvania – 1979 Meltdown – coolant water drained, temp rose, melted some of the uranium fuel rods Radiation contained in containment structure
Nuclear Power – small risk/large accidents
Nuclear Power – small risk/large accidents Chernobyl – Ukraine – 1986 – USSR Safety systems off, human error, poor design Explosion – clouds of radioactive debris 10 days before surrounding towns evacuated 31 direct deaths, thousands effected
Nuclear Power – small risk/large accidents
Nuclear Power – small risk/large accidents
Nuclear Power – small risk/large accidents
Nuclear Power – small risk/large accidents
Chernobyl Legacy http://mediastorm.org/0007.htm
Nuclear Power – Waste Disposal Spend fuel rods and any equipment in the reactor Stays radioactive for thousands of years Must be put in a stable environment Currently, most stored at Power Plants
Nuclear Power – Waste Disposal Yucca Mountain
Nuclear Power – Waste Disposal
Nuclear Power – Waste Disposal
Nuclear Power – Multiple Problems slowed growth Very expensive to build and very expensive to dismantle Western Europe decreasing capacity Asia increasing capacity USA???