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Energy Sources

Chapter 10

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Energy Sources

• Non-Renewable Energy - Energy sources used faster than can be replenished.

Coal - Oil - Natural Gas

• Renewable Energy - Continuously present as a feature of the environment (solar energy), or is continually replenished.

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All Energy Sources

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Resources and Reserves

• Resource - Naturally occurring substance of use to humans that can potentially be extracted using current technology.– Reserve - Amount of a known deposit that

can be economically extracted using current technology, under certain economic conditions.

Reserve levels change as technology advances, new discoveries are made, and profit margins change.

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Resources and Reserves

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Fossil Fuel Formation

• Coal– 300 mya plant material began collecting

underwater, initiating decay, forming a spongy mass of organic material (peat).

Due to geological changes, some of these swamps were covered by seas, and covered with sediment.

Pressure and heat over time transformed peat into coal.

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Recoverable Coal Reserves

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Oil and Natural Gas

• Accumulations of dead marine organisms on the ocean floor were covered by sediments.– Muddy rock gradually formed rock (shale)

containing dispersed oil.Sandstone formed on top of shale, thus

oil pools began to form. Natural gas often forms on top of oil.

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Crude Oil and Natural Gas Pool

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Issues Related to Fossil Fuel Use

• Fossil fuels supply 90% of world’s commercial energy.– Oil 40%– Coal 24%– Natural Gas 25%

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Coal Use Issues

• Coal is most abundant fossil fuel.– Primarily used for generating electricity.

Three Categories: Lignite

High moisture content - Least desirable.

Bituminous Most abundant - Most widely used.

Anthracite Highest energy content - Hard to

obtain.

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Coal Use Issues

• Two main extraction methods:– Surface Mining (Strip Mining)

Removes soil on top of a vein. Efficient but destructive.

– Underground MiningMinimizes surface disturbance, but costly

and dangerous. Black Lung Disease

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Fig. 10.8

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Fig. 10.7

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Coal Use Issues

• Bulky - causes some transport problems.• Mining creates dust pollution.• Burning releases pollutants (C and S).

– Millions of tons of material released into atmosphere annually.

Sulfur leads to acid mine drainage and acid deposition.

Increased amounts of atmospheric carbon dioxide implicated in global warming.

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Surface-Mine Reclamation

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Oil Use

• More concentrated than coal, burns cleaner, and is easily transported through pipelines.– Ideal for automobile use.– Difficult to extract.– Causes less environmental damage than

coal mining.

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Oil Use

• Primary Recovery– Only removes 1/3 of a deposit.

• Secondary Recovery– Force water or gas into wells.

As oil prices increase, more expensive and aggressive secondary recovery methods will need to be used.

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Oil Use Issues

• Processing – As it comes from the ground, oil is not in a

form suitable for use, and must be refined. Multiple products can be produced from a

single barrel of crude oil.• Oil Spills

– Accidental spills only account for about 1/3 of oil pollution resulting from shipping.

60% comes from routine shipping operations.

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Fig. 10.10

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Fig. 10.12

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Processing Crude Oil

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Natural Gas Use

• Drilling requirements similar to oil.• Hard to transport - flamed off at oil fields.• As demand increases, new transportation

methods will be developed and implemented.– (LPG’s) Liquefaction at -126o F

(1/600 volume of gas)• Least environmentally damaging fossil fuel.

– Almost no air pollution.• Use is increasing (45% from 1985-2003).

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Fig. 10.6

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Renewable Sources of Energy

• Currently, alternative energy sources supply almost 10% of the world’s total energy.– Suggested these sources could provide

half of the world’s energy needs by 2050.HydropowerWind TurbinesSolar CellsBiomass FuelsHydrogen Fuel

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Renewable Energy as a Share of Total Energy

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Hydroelectric Power

• Hydroelectric power is created when flowing water is captured and turned into electricity.– Damming a river and storing water in a

reservoir is the most common method.Pumped Storage Plants - Use two

reservoirs separated by a significant elevation difference.

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Hydroelectric Power

• Currently supplies 15% of world’s electricity.– China possesses 10% of world’s potential.

• Reservoir construction causes significant environmental and social damage.– Loss of farmland.– Community relocation.– Reduction of nutrient-rich silt leading to

loss of wetlands.

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Fig. 10.14

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Environmental Effects of Hydroelectric

• Flooding of vast areas of land behind dams.• Prevention of fish migrations.• Trapping of silt.

– Stops flow of nutrients downstream.– Fills in reservoir.

• Mercury Accumulation• Decaying vegetation produces greenhouse

gases.

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Tidal Power

• Daily rise and fall of ocean levels relative to coastlines (tides) are a result of gravitational forces and the revolution of the earth.– As water flows from a higher level to a

lower level, it can be used to spin an electricity - generating turbine.

Areas near the poles, and in narrow bays and estuaries are ideal but limited.

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Fig. 10.16

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Geothermal• In some areas, molten material is close

enough to surface to heat underground water and form steam - drilled and captured.– Only practical in limited areas.– California produces 40% of world’s

geothermal electricity.– Can cause unpleasant odors and high

mineral content leads to high maintenance.Corroded pipes and equipment.

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Geothermal Energy

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Wind• As warm air becomes less dense and rises,

cooler, denser, air flows in to take its place.• U.S. Department of Energy has stated the

Great Plains could supply 48 states with 75% of their electricity.– Cost becoming very competitive with

various fossil fuel sources. Currently 3-6 cents per kilowatt hour

compared to 38 cents (1980’s) due to technological advances.

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Wind

• Potential Problems– Steady,dependable wind source is critical.

Wide open areas are most desirable.– Can be hazardous to birds.– Produce noise and visual pollution.– Vibrations can cause structural damage.

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Darrieus Rotor

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Solar

• Daily energy from the sun is six hundred times greater than energy produced each day by all other energy sources combined.– Weather dependent.

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Three Major Use Categories

• Passive Heating - Sun’s energy is converted directly to heat and used at collection site.– South-Facing Windows.

• Active Heating - Sun’s energy converted into heat, but transported elsewhere to be used.– Domestic Water Heating

• Electrical Generation - Solar energy is transformed into electrical energy.– Photovoltaic

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Fig. 10.19

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Fig. 10.20

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Photovoltaic Cells

• Solid-state semiconductors that allow direct conversion of sunlight to electricity.– Developed in 1954 by Bell Laboratories.

Amount of PV power installed worldwide has increased from 100 megawatts in 1992 to 1,200 megawatts in 2002.

Film technology has made it possible to build solar cells into roof tiles, skylights, and other building materials.

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Photovoltaic Cells

• Photovoltaics will be the most practical choice for generation of electricity in rural areas and less developed countries.– In place of generators that require fuel and

centralized power plants that require distribution lines.

– Prices have decreased.

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Biomass Conversion

• Biomass is still the predominant form of energy used by people in less-developed countries.– Account for 14% of world energy use.

• Three Distinct Sources:– Municipal and Industrial Wastes– Agricultural Crop Residue– Energy Plantations

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Fig. 10.22

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Biomass Conversion

• Releasing chemical energy stored in biomass.– Burned directly for heat.– Burned to produce electricity.– Converted to alcohol or used to generate

methane. • Costs depends on type of technology used,

size of the power plant, and the cost of biomass supply.– Currently as low as 9 cents per kilowatt

hour.

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Fig. 10.23

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Fuel wood

• In less-developed countries, fuelwood has been major energy source for centuries.

• Fuelwood is primary energy source for nearly half world’s population.

• Due to intense population growth, an estimated 1.3 billion people cannot get enough fuel wood, or are using it faster than rate of regeneration.

• Source of air pollution and fly ash.

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Fig. 10.24

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Solid Waste

• Using municipal waste as a source of energy:– Reduces landfill volume.

Not economically profitable. Must be sorted. Requires large, sustainable volume.

– Produces air pollution.Chlorine-containing organic compounds.

CFCs

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Fig. 10.25

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Table 10.2

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Energy Conservation

• Conservation is not a way of generating electricity, but a way of reducing need for additional energy production/consumption and saving money for the consumer.– Lighting and air conditioning account for

25% of U.S. electricity consumption.Widespread use of energy-efficient

lighting could significantly reduce energy consumption.

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Energy Conservation

• Energy-inefficient machines can be produced very cheaply.– Long-term vs. short-term costs.

• Electrical utilities will lead energy conservation charge.– Conservation is cheaper than building more

power plants to meet increased demands.

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Fig. 10.26

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Hydrogen Economy

• Hydrogen is abundant and generates heat and pure water when it reacts with air.– Hydrogen Fuel Cells

Proton Exchange Membrane Fuel Cell Self-Sustaining Low Operating Temperature No Pollution

Successor to internal combustion engine.

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Simple Fuel Cell

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Fig. 10.28

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Table 10.3