Issues with petroleum Limited reserves (near peak in Hubbert curve) Trade deficit (most oil imported) Externalities (military costs, environmental impacts) Environmental pollution (persistent combustion products, toxic components of oil, greenhouse gases, etc) Alternatives: Coal, the other black fuel US coal reserves ~400y 1
Problems with coal Dirtiest of fossil fuels Strip mining degrades land Many pollutants emitted from coal-fired power plants: sulfur dioxide, nitrogen oxides, carbon dioxide, mercury, and others But, the most important fuel for producing electricity in the US CO 2 emissions from US fossil fuels Environmental impacts of coal Kingston Fossil Plant coal fly ash spill Dec. 2008 >1 billion gallons of coal ash slurry released Covered 300 acres 2
Production of electricity Energy Conversions Chemical Radiant Electrical Mechanical Heat Nuclear Reactor Boiler Chemical fuel cell Burner (Fossil Fuel) generator Radiant photolysis Photovoltaic cell Absorber Electrical electrolysis lamp, electric motor resistance battery charging laser heat pump Mechanical electric generator friction Heat thermoelectric thermo-dynamic generator engines (inefficient) (inefficient) Energy outlook Petroleum: Limitation in ~10y Natural Gas: 50 y of reserves in the U.S. Coal: about 400 y of reserves What can we do about the impending oil shortage? Short term: Increase fuel efficiency of vehicles Longer term: Alternative fuels for transportation Increased efficiency and alternative sources for electricity Is nuclear power the best alternative energy source? 3
"The most important responsibility of this atomic energy agency would be to devise methods whereby this fissionable material would be allocated to serve the peaceful pursuits of mankind. Experts would be mobilized to apply atomic energy to the needs of agriculture, medicine and other peaceful activities. A special purpose would be to provide abundant electrical energy in the power-starved areas of the world" Dwight D. Eisenhower on the International Atomic Energy Agency (1953) What s the best energy policy? 1: Conservation 2: Which energy sources should we develop? Petroleum (trade, national security, pollution) Coal (air and water pollution) Nuclear (hazards) Renewable energy Hydroelectric (dams)? Solar (technological challenges) Natural gas (transport) Biomass (landscape changes, food production) Wind Tidal power Nuclear Power Topics for today Terms and concepts How does it work? Nuclear power in the U.S. and the world Problems with nuclear power 4
Spontaneous Fission Nuclear Fission 1n + 235 U 236 U (fission) 140 Ba + 93 Kr + 3n (slow) (or 140 Cs + 93 Rb + 3n) Mass of 235 U + 1n is greater than the mass of 140 Ba + 93 Kr + 3 n 5
E = mc 2 Nuclear Power Step-by-step Refine uranium from uranium-bearing rock Enrich the uranium in 235 U (~ 0.7% of total U) (4% 235 U), very difficult to separate 235 U from 238 U Methods: Diffusion of UF 6 through a membrane, centrifugation Create a fuel geometry that can be controlled Fuel rods: contains the uranium ore Moderator: slows neutrons Control rods: absorbs neutrons to stop the nuclear reaction Connect the nuclear vessel to a steam generator and turbine for producing electricity Controlling the nuclear reaction Control rods absorb neutrons stopping reaction Moderator (H 2 O) slows neutrons to allow fission 6
Heat released generates steam, which turns a turbine, which turns a generator to make electricity Nuclear Power Abroad Data from the IAEA Nuclear Power Abroad Data from the IAEA 7
Nuclear power in the U.S. Hanford, WA Ages of 435 nuclear power plants 35 30 Number of reactors 25 20 15 10 5 0 0 10 20 30 40 Nuclear reactor age (y) Data from the IAEA No new orders for nuclear power plants in US since 1974 Why not? Figure from Wright and Nebel, 2002 8
Nuclear Power Hazards Uranium mining and purification is not clean (e.g., Hanford, WA) Spent fuel is toxic for tens of thousands of years 239 Pu made (24,000y half life) in nuclear plants from 238 U Storage sites: At nuclear power plants Yucca mountain, Nevada Waste Isolation Pilot Plant (New Mexico) Potential for accidents (e.g., Chernobyl, 3-mi Isl) 1979: Three-mile Island, The China Syndrome released Potential for theft of fissionable material - during storage, transport Reactors under construction abroad Data from IAEA DOE Nuclear Waste Sites 9
3 Mile Island March 1979, Middletown PA Partial meltdown due to equipment malfunction, worker error and design problems Chernobyl: 1000s of miles of fallout Chernobyl A major nuclear accident anywhere is a nuclear accident everywhere. Exposed 0.5 million people to dangerous levels of radioactivity 400,000 people relocated Area the size of Florida is highly contaminated Ukrainian Ministry of Heath estimates 125,000 deaths and, 3.5 million ill because of exposure to radioactive material 10
Accidents at nuclear plants Accidents per 1,000,000 person-hours (right) Source: IAEA Controlling a nuclear power plant http://www.ida.liu.se/~her/npp/demo.html Hanford Site 239 Pu production for WWII Manhattan project 40 billion gallons of waste dumped into soil 177 huge underground tanks, ⅓ leaking in 2001 Contaminated groundwater moving toward Columbia R. 60 billion spent on cleanup so far, 200 billion more estimated World s largest cleanup site 11
U.S. Options for Electricity Coal Nuclear Nuclear proliferation Other problems N. Korea Iran Others? $800+ billion economic stimulus package $50 billion in loan guarantees for nuclear power (and liquid coal) Should the U.S. invest in more nuclear power plants to meet rising demands for energy? 12
Energy outlook Petroleum: Limitation in ~10y? Natural Gas: 50 y of reserves in the U.S. Coal: about 400 y of reserves What about renewable energy? US Department of Energy: December 5, 2006 New World Record Achieved in Solar Cell Technology New Solar Cell Breaks the 40 Percent Efficient Sunlight-to-Electricity Barrier WASHINGTON, DC U.S. Department of Energy (DOE) Assistant Secretary for Energy Efficiency and Renewable Energy Alexander Karsner today announced that with DOE funding, a concentrator solar cell produced by Boeing-Spectrolab has recently achieved a world-record conversion efficiency of 40.7 percent, establishing a new milestone in sunlight-to-electricity performance. This breakthrough may lead to systems with an installation cost of only $3 per watt, producing electricity at a cost of 8-10 cents per kilowatt/hour, making solar electricity a more cost-competitive and integral part of our nation s energy mix. 13
Problems and promises of renewable energy Types of renewable energy and their conversion Solar power Hydrogen and fuel cells Other forms of renewable Energy Hydroelectric Geothermal Biomass Geographical constraints and other challenges Energy Conversions Chemical Radiant Electrical Mechanical Heat Nuclear Reactor Boiler Chemical fuel cell Burner (Fossil Fuel) generator Radiant photolysis Photovoltaic cell Absorber Electrical electrolysis lamp, electric motor resistance battery charging laser heat pump Mechanical electric generator friction Heat thermoelectric thermo-dynamic generator engines (inefficient) (inefficient) Electricity generation in WA Figure 2. Industry Generation by Energy Source, 1999 (Data from US EIA) 14
Sources of renewable energy in US Energy Source Total Energy Electricity Hydroelectric 44.6% 75.2% Biomass 46.5% 16.7% Geothermal 5.6% 4.0% Wind 2.3% 3.9% Solar 1.0% 0.2% Solar Energy: Direct conversion of radiant energy to heat or to electricity Solar water heater Passive solar home heating Solar Thermal-Electric Power Plants Solar thermal energy focused on a heat exchanger to produce electric power 15
US Electricity from Renewable E US electricity generation in 2004: 9% Renewable E Solar power: 0.018% of electricity generation in 2004 Why such a small percentage? (Data from US EIA) Challenges of solar power Cost Variable supply of radiant energy Energy storage challenges Geographic distribution of sunshine Requires energy to build photo-voltaic cells 16
Hydroelectric Power Constraints on renewable energy sources Solar, wind, geothermal, hydroelectric Geographic constraints Limited current usage Environmental risks Tidal power in Puget Sound? Snohomish County PUD proposed tidal power for Admiralty Inlet Will tidal-power turbines create clean energy or salmon sushi? 17
What can we do? Which energy sources are best: coal, natural gas, oil, nuclear, hydroelectric, other renewable energy sources? How can we expand renewable energy use? How can we increase efficiency of energy use (residential, industrial, transportation)? How can we in develop alternative energy sources for transportation? 18