1 conventional “nonrenewable” energy. 2 evaluating energy resources u.s. has 4.6% of world...

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Conventional “Nonrenewable” Energy

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Evaluating Energy ResourcesEvaluating Energy Resources

• U.S. has 4.6% of world population; uses 24% of the world’s energy;

84% from nonrenewable fossil fuels (oil, coal, & natural gas);

7% from nuclear power;

9% from renewable sources (hydropower, geothermal, solar, biomass).

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Changes in U.S. Energy UseChanges in U.S. Energy Use

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Energy resources removed from the earth’s crust include: oil, natural gas, coal, and uranium

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Fossil FuelsFossil Fuels

• Fossil fuels originated from the decay of living organisms millions of years ago

• The fossil fuels used in energy generation are:Natural gas, which is 70 - 80% methane (CH4)PetroleumCoal

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Problems with Fossil FuelsProblems with Fossil Fuels

• Nonrenewable resources• Impurities = major source of pollution

• Produce large amounts of CO2

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COAL

• Coal-fossilized plant material preserved in sediments, compacted and condensed over time to create a solid fossil fuel Made up of:

- Carbon- Water, sulfur, mercury and small amounts of

radioactive materials As coal ages, carbon ↑ while water ↓ Carboniferous period (286 million to 360

million years ago).

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Types of Coal

• Peat Partially decayed organic matter in swamps and bogs

• Lignite (4000 BTU/lb) Soft, brownish-black coal Low quality of coal

• Subbituminous (8,300 BTU/lb.) Black lignite

• Bituminous (10,500 Btu / lb.) Dense and black Most common coal “soft coal”

• Anthracite (14,000 Btu/lb) 98% carbon (less common and more expensive) “hard coal”

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PEATPEAT

LIGNITELIGNITE

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BITUMINOUSBITUMINOUS

ANTHRACITEANTHRACITE

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Main Coal DepositsMain Coal Deposits

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Pros and Cons of Coal

• Pros: Most abundant fossil fuel Major U.S. reserves High net energy yield

• Cons: High environmental impact

- Severe land disturbance in mining High carbon dioxide (dirtiest fuel) Sulfur is released primarily as sulfur dioxide Releases radioactive particles and toxic metals

into the atmosphere

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Cons of Coal Cont.

Negative impact on miners- Death

Between 1870 and 1950, more than 30,000 coal miners died of accidents and injuries in Pennsylvania alone.

- Black Lung Disease - Inflammation and fibrosis caused by accumulation of coal dust in the lungs or airways.

- Several thousands have died of respiratory diseases.

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Mining

• 2 types of mining Strip-Mining or Open Pit Mining

- Topsoil and vegetation is removed- Negative impacts

Air quality issues regarding dust Large amounts of waste material involved Habitats destroyed/Soil is dumped back to

where it was Toxic runoff

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Mining

• Underground Mining-large shafts dug into the earth Less surface destruction and waste rock

produced Extremely Dangerous

- Gas- Inhaling Particulate Matter- Tunnel Collapse- Acid mine drainage

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Acid Mine Drainage (AMD)

• Acid mine drainage-water containing iron and sulfate that contaminates surface and or groundwater May also contain manganese and aluminum AMD comes from oxidation of pyrite, the

crystalline form of iron sulfide - contaminated water is often reddish-brown

in color, indicating high levels of oxidized iron

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Restoration

• Surface Mining Control and Reclamation Act (1977) requires better restoration of strip-mined lands, especially if land classed as prime farmland. Difficult and expensive.

- Minimum reclamation costs about $1,000 / acre while complete restoration may cost $5,000 / acre.

50% of U.S. coal is strip mined.

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OilOil

• Decomposition of deeply buried organic matter from plants & animals Crude oil: complex liquid mixture of

hydrocarbons, with small amounts of S, O, N impurities

• Trapped within the earth's crust and can be extracted by drilling a well

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Sources of OilSources of Oil

•Organization of Petroleum Exporting Countries (OPEC) -- 13 countries have 67% world reserves:

• Algeria, Ecuador, Gabon, Indonesia, Iran, Iraq, Kuwait, Libya, Nigeria, Qatar, Saudi Arabia, United Arab Emirates, & Venezuela

• Other important producers: Alaska, Siberia, & Mexico.

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Oil in North AmericaOil in North America•2.3% of world reserves

•uses nearly 30% of world reserves;

•65% for transportation;

•increasing dependence on imports. www.bio.miami.edu/beck/esc101/Chapter14&15.ppt

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Low oil prices have stimulated economic growth, they have discouraged / prevented improvements in energy efficiency and alternative technologies favoring renewable resources.

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Oil Drilling

• Causes only moderate damage to earth’s land- Oil companies extract oil in fragile

environments (Artic tundra/Alaska)• Transported to a refinery where it is heated and

distilled to separate the components

• How Oil Drilling Works by Craig C. Freudenrich, Ph.D.

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Oil Sands

• Mixture of roughly 90% sand, clay and water and 10% bitumen, a thick hydrocarbon liquid Extract oil from tar sands by injecting hot

steam, which heats the sands and makes the tar less viscous so that it can be pumped out

- the bitumen can be purified and refined into synthetic crude oil.

• WHERE: Alberta, Canada, Saudi Arabia, Venezuela and the Middle East

• Keystone Pipeline

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Natural Gas - Fossil FuelNatural Gas - Fossil Fuel

• Mixture •50–90% Methane (CH4)

•Ethane (C2H6)

•Propane (C3H8)

•Butane (C4H10)

•Hydrogen sulfide (H2S)www.bio.miami.edu/beck/esc101/Chapter14&15.ppt

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Sources of Natural GasSources of Natural Gas

•Russia & Kazakhstan - almost 40% of world's supply.

•Iran (15%), Qatar (5%), Saudi Arabia (4%), Algeria (4%), United States (3%), Nigeria (3%), Venezuela (3%);

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billion cubic metres

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Natural GasNatural Gas

• Experts predict increased use of natural gas during this century

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Hydraulic Fracking

• Wells drilled • Fluids are pumped at high pressure causing

fissures in shale made up of water, chemical, and sand

additives- Sand keeps the fractures from closing

• Gas flows up the well• When fracking is completed, injected fracturing

fluids rise to the surface

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Nuclear Energy

• Most commonly used fuel is U235

- Formed in cylindrical pellets (1.5 cm long) and stacked in hollow metal rods (4 m long).

• Mined through open pit or underground Low uranium content in ore-large amounts

have to be mined- Large amounts of waste rock

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How Do Nuclear Reactors Work?

• Nuclear Fission Chain Reactor-neutrons strike U-235 releasing energy and more neutrons. Triggers nuclear chain reaction. Heats water that produce high-pressure steam

that turns turbines-generates electricity.

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Nuclear Fission

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Parts of a Nuclear Reactor

• Core-contains 35-50,000 long thin fuel rods packed with U235

Each pellet contains the energy equivalent of 1 ton of coal)

• Control rods-absorb neutrons and controls reaction rate Raising and lowering the control rods into the reactor

regulates the amount of heat produced• Moderator-reduces velocity of fast moving neutrons

Water, graphite• Coolant-(water) circulates through the reactor’s core to

remove heat to keep fuel rods from melting

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PWR

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Radioactive Waste Disposal

• High level wastes-used fuel rods, control rods, water used to cool and control chain reactions

• Medium to low level wastes-mine wastes, contaminated protective clothes of a power plant worker

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Three Mile IslandThree Mile Island

•March 29, 1979, a reactor near Harrisburg, PA lost coolant water because of mechanical and human errors and suffered a partial meltdown

•50,000 people evacuated & another 50,000 fled area

•Unknown amounts of radioactive materials released

•Partial cleanup & damages cost $1.2 billion

•Released radiation increased cancer rates.

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ChernobylChernobyl• April 26, 1986, reactor explosion (Ukraine) with a severe release of radioactivity• No containment vessels• Plume of radioactivity drifted over extensive parts of western Europe and 336,000 people were resettled

• ~160,000 sq km (62,00 sq mi) contaminated

• > Half million people exposed to dangerous levels of radioactivity

• Cost of incident > $358 billion

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Japan: Tokyo Electric Power Company's (TEPCO) Fukushima Daiichi

• 3/11/11: 9.0 earthquake caused tsunami that went over seawalls and flooded generators Generators died which stopped the coolant pumps Temperature rose above 2200ºF caused several

explosions Pumped sea water mixed with boron into the

containment vessels• Residents living within 20 kilometers of the plant are

told to evacuate the area after first explosions.• Estimated cost of damage from the earthquake and

tsunami to top $300 billion, making it the world's costliest natural disaster.

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Use of Nuclear EnergyUse of Nuclear Energy• Some countries (France, Japan) investing increasingly

• France 58 reactors supply 75% energy • Japan 54 reactors supply 29% of energy

• U.S. 104 reactors supply 20% energy• 1996 last new reactor opened• Cost today: ~$10 billion • 71,862 tons of the waste and no permanent place to store it all. • ¾ of waste stored in water-filled cooling pools stored inside

concrete containment barriers • ¼ waste is encased in "dry casks" constructed of steel and

thick concrete.• Yucca Mountain in Nevada

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Nuclear Power Plants in U.S.Nuclear Power Plants in U.S.

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Energy Units and UseEnergy Units and Use

• Btu (British thermal unit) - amount of energy required to raise the temperature of 1 lb of water by 1 ºF.

• cal (calorie) - amount of energy required to raise the temperature of 1 g of water by 1 ºC. Commonly, kilocalorie (kcal) is used.

1 Btu = 252 cal = 0.252 kcal

1 Btu = 1055 J (joule) = 1.055 kJ

1 cal = 4.184 J

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• Units of power:Units of power:

1 watt (W) = 3.412 Btu / hour1 watt (W) = 3.412 Btu / hour

1 horsepower (hp) = 746 W1 horsepower (hp) = 746 W

• Watt-hour - Another unit of energy used only to Watt-hour - Another unit of energy used only to describe electrical energy. Usually we use describe electrical energy. Usually we use kilowatt-hour (kW-h) since it is larger.kilowatt-hour (kW-h) since it is larger.

Energy Units and UseEnergy Units and Use

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