1. Achieving Energy Independence Environmental Science 6.3

2. Thank You, Thomas Edison Turbine – machine w/ several curved blades on a large rotating shaft Generator – stationary coils of copper wire and an electromagnet First commercial electric generating station (designed by Thomas Edison) burned coal to heat water and produce steam; steam turned turbines

3. 70% of electricity in the U.S. produced at power plants that burn fossil fuels (mostly coal) Nuclear power plants produce 20% Renewable energy produces remaining 10%

4. Hydroelectric Power Cheaper than electricity from fossil-fueled power plants Do not produce air pollution or heat Can have significant impacts on the environment

5. Nuclear Power Uranium atoms undergo fission (splitting) Fission releases huge amounts of energy Heats water and creates steam that drives turbines Clean source of energy (no air pollution) Nonrenewable resource, but uranium supply will last many years More expensive to construct

6. Safety is major concern ◦ 1979 - Three Mile Island accident  Core in one of the reactors partially melted ◦ 1986 - Chernobyl Nuclear Plant in Ukraine killed 30 people initially; 1000s more increased risk of cancer  Highest levels of radioactive fallout ever recorded No new plants have been built since TMI Spent fuel is highly radioactive ◦ Storage

7. Geothermal Energy Geothermal energy – natural heat or hot water trapped below the earth’s surface Steam or hot water is pumped to the earth’s surface and is used to drive turbines Corrosive minerals can damage pipes and turbine Harmful gases may be vented Can contaminate aquifers

8. The Geysers (naturally occurring steam field in CA) is largest complex of geothermal power plants in the world Relatively constant temp. of the earth is warmer than the air above it in the winter and cooler in the summer ◦ Can be used directly by geothermal heat pumps to transfer heat using an open or closed loop system

9. Solar Energy New houses are designed w/ windows facing sun Passive solar heating – occurs when light energy passes through glass and is trapped (greenhouse effect) Thermal mass – large containers of water or floors and walls made of brick, stone, or concrete ◦ Amount of solar energy stored as heat energy can be increased

10. Active solar heating system – requires electricity for pumps or fans that distribute the heat Photovoltaic cells (solar cells) – convert sunlight directly into electricity ◦ When sunlight strikes a thin layer of silicon, electrons are released creating an electric current Solar thermal technology uses either mirror- lined dishes or panels that rotate w/ the sun and collect solar energy

11. Wind Machines At many sites the wind is not reliable enough to generate power Expensive equipment Changes appearance of the landscape Creates noise Electricity costs less

12. Biomass Biomass – any organic substances produced by living organisms and used as a source of energy ◦ Wood, agricultural crops, municipal solid wastes, waste from food processing, animals, aquatic plants Cogeneration - using one system to produce both electricity and heat for an industrial process ◦ 80% efficient

13. Gasohol – blend of one part ethanol (distilled from corn) and nine parts of gasoline Biodiesel – made from soybeans or vegetable oil and can replace or be blended w/ diesel made from crude oil