1

Issues with petroleum

• Limited reserves (near peak in Hubbertcurve)

• 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

2

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

CO2 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

3

Production of electricity

Energy Conversions

Chemical Radiant Electrical Mechanical Heat

Nuclear ReactorBoiler

Chemical fuel cell Burner(Fossil Fuel) generator

Radiant photolysis Photovoltaic cell Absorber

Electrical electrolysis lamp, electric motor resistancebattery charging laser heat pump

Mechanical electric generator friction

Heat thermoelectric thermo-dynamicgenerator 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?

4

"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

5

Spontaneous Fission

Nuclear Fission

• 1n + 235U→ 236U (fission)→ 140Ba + 93Kr + 3n(slow) (or 140Cs + 93Rb + 3n)

• Mass of 235U + 1n

is greater than the mass of

140Ba + 93Kr + 3 n

6

E = mc2

Nuclear Power – Step-by-step• Refine uranium from uranium-bearing rock

• Enrich the uranium in 235U (~ 0.7% of total U) (4% 235U), very difficult to separate 235U from 238U – Methods: Diffusion of UF6through 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 (H2O) slows neutrons to allow fission

7

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

8

Nuclear power in the U.S.

Hanford, WA

0 10 20 30 40Nuclear reactor age (y)

Num

ber o

f rea

ctor

s

0

5

10

15

20

25

30

35

Data from the IAEA

Ages of 435 nuclear power plants

No new orders for nuclear power plants in US since 1974 – Why not?

Figure from Wright and Nebel, 2002

9

Nuclear Power Hazards• Uranium mining and purification is not clean

(e.g., Hanford, WA)• Spent fuel is toxic for tens of thousands of years

239Pu made (24,000y half life) in nuclear plants from 238UStorage 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

Data from IAEA

Reactors under construction abroad

DOE Nuclear Waste Sites

10

3 – Mile IslandMarch 1979, Middletown PA

Partial meltdown due to equipment malfunction, workererror 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

11

Accidents at nuclear plants

Source: IAEAAccidents per 1,000,000 person-hours (right)

Controlling a nuclear power plant

http://www.ida.liu.se/~her/npp/demo.html

• 239Pu 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

Hanford Site

12

U.S. Options for Electricity

• Coal

• Nuclear

Other problems

• Nuclear proliferation

N. KoreaIranOthers?

$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?

13

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, producingelectricity 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.

14

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 ReactorBoiler

Chemical fuel cell Burner(Fossil Fuel) generator

Radiant photolysis Photovoltaic cell Absorber

Electrical electrolysis lamp, electric motor resistancebattery charging laser heat pump

Mechanical electric generator friction

Heat thermoelectric thermo-dynamicgenerator engines(inefficient) (inefficient)

Electricity generation in WA

Figure 2. Industry Generation by Energy Source, 1999

(Data from US EIA)

15

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%

Sources of renewable energy in US

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

16

US Electricity from Renewable E

Solar power: 0.018% of electricity generation in 2004Why such a small percentage? (Data from US EIA)

US electricity generation in 2004: 9% Renewable E

Challenges of solar power

• Cost• Variable supply of radiant

energy• Energy storage challenges• Geographic distribution of

sunshine• Requires energy to build

photo-voltaic cells

17

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?

18

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?