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Environmental Science Chapter 13: Energy. Key Concepts Energy use in the U.S. and around world Tradeoffs of different fossil fuels Tradeoffs of nuclear.

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Presentation on theme: "Environmental Science Chapter 13: Energy. Key Concepts Energy use in the U.S. and around world Tradeoffs of different fossil fuels Tradeoffs of nuclear."— Presentation transcript:

1 Environmental Science Chapter 13: Energy

2 Key Concepts Energy use in the U.S. and around world Tradeoffs of different fossil fuels Tradeoffs of nuclear energy Improving energy efficiency Energy saving options for cars

3 Fig. 13-3, p. 287 Commercial Energy for the World and US

4 Fig. 13-4, p. 288 Year 21002025195018751800 0 20 40 60 80 100 Contribution to total energy consumption (percent) Wood Coal Oil Nuclear Hydrogen Solar Natural gas Commercial Energy Use in US Since 1800

5 Fig. 13-5a, p. 289 Space Heating Passive solar Natural gas Oil Active solar Coal gasification Electric resistance heating (coal-fired plant) Electric resistance heating (natural-gas -fired plant) Electric resistance heating (nuclear plant) 0.3 0.4 1.5 1.9 4.5 4.9 5.8 Net Energy Ratios

6 Fig. 13-7, p. 292 Major Oil, Natural Gas, and Coal Deposits in North America

7 Ample supply for 42-93 years Low cost (with huge subsidies) High net energy yield Easily transported within and between countries Low land use Technology is well developed Efficient distribution system Advantages Trade-Offs Conventional Oil Disadvantages Need to find substitute within 50 years Artifically low price encourages waste and discourages search for alternative Air pollution when burned Releases CO 2 when burned Moderate water pollution Fig. 13-9, p. 293 Tradeoffs of Conventional Oil Use

8 Carbon Dioxide Emissions Per Unit Energy of Different Fuels Nuclear power Natural gas Oil Coal Synthetic oil and gas produced from coal Coal-fired electricity 17% 58% 86% 100% 150% 286% Fig. 13-10, p. 294 Oil sand 92%

9 Good fuel for fuel cells and gas turbines Low land use Easily transported by pipeline Moderate environmental impact Lower CO 2 emissions than other fossil fuels Less air pollution than other fossil fuels Low cost (with huge subsidies) High net energy yield Ample supplies (125 years) Sometimes burned off and wasted at wells because of low price Shipped across ocean as highly explosive LNG Methane (a greenhouse gas) can leak from pipelines Releases CO 2 when burned Nonrenewable resource Difficult to transfer from one country to another Requires pipelines Advantages Trade-Offs Conventional Natural Gas Disadvantages Fig. 13-13, p. 296 Tradeoffs of Natural Gas

10 Fig. 13-14, p. 296 Increasing moisture content Increasing heat and carbon content Peat (not a coal) Lignite (brown coal) Bituminous Coal (soft coal) Anthracite (hard coal) Heat Pressure Heat Partially decayed plant matter in swamps and bogs; low heat content Low heat content; low sulfur content; limited supplies in most areas Extensively used as a fuel because of its high heat content and large supplies; normally has a high sulfur content Highly desirable fuel because of its high heat content and low sulfur content; supplies are limited in most areas Coal

11 Low cost (with huge subsidies) High net energy yield Ample supplies (225–900 years) Releases radioactive particles and mercury into air High CO 2 emissions when burned Severe threat to human health High land use (including mining) Severe land disturbance, air pollution, and water pollution Very high environmental impact Mining and combustion technology well- developed Air pollution can be reduced with improved technology (but adds to cost) Advantages Trade-Offs Coal Disadvantages Fig. 13-15, p. 297 Tradeoffs of Coal

12 Low risk of accidents because of multiple safety systems (except in 35 poorly designed and run reactors in former Soviet Union and Eastern Europe) Moderate land use Moderate land disruption and water pollution (without accidents) Emits 1/6 as much CO 2 as coal Low environmental impact (without accidents) Large fuel supply Spreads knowledge and technology for building nuclear weapons No widely acceptable solution for long-term storage of radioactive wastes and decommissioning worn-out plants Catastrophic accidents can happen (Chernobyl) High environmental impact (with major accidents) Low net energy yield High cost (even with large subsidies) Subject to terrorist attacks Advantages Trade-Offs Conventional Nuclear Fuel Cycle Disadvantages Fig. 13-19, p. 301 Tradeoffs of Nuclear Power

13 Chernobyl fallout – April 26, 1986

14 Improving Energy Efficiency Big four energy-wasting devices Incandescent light bulb – wastes 95% of its energy input Nuclear power plants – 86% wasted Internal combustion engine (e.g., car) – 75-80% wasted Coal-burning power plants – 67% wasted

15 Saving Energy: Cars Fuel-efficient cars account for <1% of all car sales in U.S. Relatively low cost of fuel Preference of SUVs and trucks Government’s failure to increase fuel economy standards

16 Fig. 13-24, p. 309 Hybrid Gas- Electric Car RegulatorFuel Tank Trans- mission Battery bank Combustion engine Electric motor Fuel Electricity

17 Fuel-cell stack Converts hydrogen fuel into electricity Front crush zone Absorbs crash energy Electric wheel motors Provide four-wheel drive Have built-in brakes Hydrogen fuel tanks Air system management Body attachments Mechanical locks that secure the body to the chassis Universal docking connection Connects the chassis with the Drive-by-wire system in the body Rear crush zone absorbs crash energy Drive-by-wire system controls Side mounted radiators Release heat generated by the fuel cell, vehicle electronics, and wheel motors Cabin heating unit Fig. 13-25a, p. 310 Hydrogen Fuel-Cell Car © 2006 Brooks/Cole - Thomson

18 Fig. 13-25b, p. 310 Hydrogen Fuel-Cell Car

19 What is E-85? Flex-fuel vehicles can run on gas or any ethanol-gas mixture Currently produced by Ford, Chrysler and GM E-85 85% ethanol / 15% gasoline Florida only has 2 stations and neither are accessible to the public

20 Other Alternative Fuels Biodiesel P-series http://www.eere.energy.gov/afdc/altfuel/altf uels.html http://www.eere.energy.gov/afdc/altfuel/altf uels.html Compare different fuels Find fueling stations More information

21 Number of E85 stations

22 Any Questions? News Story… Algal Fuel


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