In your notes… What are the four ways we harness solar energy? What are the limitations of solar energy (at least 2)? What approach should we take with alternative energies in solving the energy crisis we have looming?

Fission The splitting of atomic nuclei in a chain reaction to release energy (fission) Animation chain reaction

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Fission Produces about 20% of the electricity in this country

Nuclear = Not Renewable The radioactive form of Uranium, U235 (isotope) is required and not commonly found Uranium must be mined. Mining is dangerous because of the slow release of radioactivity

Radioactivity The nucleus of atoms are in an unstable state releasing protons and neutrons causing the element to change (decay) into another form, eventually lead. Radioactivity is found in nature but it is harmful to living cells in high dosages (fission releases a tremendous amount of radioactivity) Navajo moviemovie

Produces electricity Just like fossil fuel power plants, but contains a nuclear reactor to produce heat.

How Nuclear power works Video

Energy in U235 Typical Heat Values of Fuels Firewood: 16 MJ/kg Black coal:24-30 MJ/kg Crude Oil: MJ/kg Uranium: 500,000 MJ/k (MJ = Megajoules), *natural U 2 pounds of U235 has the same energy as 16 tons of coal

Impacts No air pollution There is radioactive waste from mines, processing, and disposal of uranium

Nuclear Fast Facts Since the mid-1940s, spent nuclear fuel and high-level radioactive waste have accumulated throughout the country. Currently, they are stored in temporary facilities at some 121 sites in 39 states. These storage sites are located in a mixture of urban, suburban, and rural environments — most are located near large bodies of water. In the United States today, over 161 million people reside within 75 miles of temporarily stored nuclear waste. As of 1996 there was a cumulative total of 32,000 metric tons of irradiated fuel from commercial nuclear power generation in the United States, nearly all of it at the reactor sites.

Yucca Mountain

Impacts... Many people fear power plants due to possible meltdowns (when nuclear fuel becomes too hot and escapes the reactor chamber releasing radioactivity into the surrounding. A partial meltdown occurred at Three Mile Island (PA) in 1979 Worst meltdown occurred at Chernobyl (Ukraine ) Bill Nye Fukushima Nuclear Meltdown 2011 At home?

Impacts Con’t Worst meltdown occurred at Chernobyl (Ukraine ) pg 451 Aging plants must be maintained which is very expensive. 81 reactors have been taken out of service worldwide. Dealing with nuclear material in any way is very costly New technology may change plant design making them much safer. Nuclear power will most likely decline until changes occur

Nuclear Fusion Fusion occurs when hydrogen isotopes are combined to release energy forming helium gas as a by-product One gram of deuterium fusion fuel = 45 barrels of oil. Extremely high temperatures are needed to strip the hydrogen atoms of the electrons making a plasma. This process occurs in the Sun * This process has only occurred experimentally