Post on 26-Mar-2015
transcript
Nonrenewable EnergyNonrenewable EnergyResourcesResources
Chapter 17Chapter 17
Advanced Placement Environmental Science
1. Energy Resources1. Energy Resources
2. Oil
3. Natural Gas
4. Coal
5. Nuclear Energy
Energy SourcesEnergy SourcesModern society requires large quantities of energy that
are generated from the earth’s natural resources.
Primary Energy Resources: The fossil fuels(oil, gas, and coal), nuclear energy, falling water, geothermal, and solar energy.
Secondary Energy Resources: Those sources which are derived from primary resources such as electricity, fuels from coal, (synthetic natural gas and synthetic gasoline), as well as alcohol fuels.
ThermodynamicsThermodynamics
The laws of thermodynamics tell us two things about converting heat energy from steam to work:
1)1) The conversion of heat to work cannot be 100 % efficient because a portion of the heat is wasted.
2)2) The efficiency of converting heat to work increases as the heat temperature increases.
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) - the 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
Two other units that are often seen are the horsepower Two other units that are often seen are the horsepower and the watt. These are not units of energy, but are and the watt. These are not units of energy, but are 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 kilowatt-describe electrical energy. Usually we use kilowatt-hour (kW-h) since it is larger.hour (kW-h) since it is larger.
quad (Q) - used for describing very large quantities of quad (Q) - used for describing very large quantities of energy. 1 Q = 10energy. 1 Q = 101515 Btu Btu
Energy Units and UseEnergy Units and Use
Evaluating Energy ResourcesEvaluating Energy Resources
U.S. has 4.6% of world population and 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).
Changes in U.S. Energy UseChanges in U.S. Energy Use
Energy resources removed from the Earth’s crust include: oil, natural gas, coal, and uranium.
Fossil FuelsFossil FuelsFossil fuels originated from the decay of
living organisms millions of years ago, and account for about 80% of the energy generated in the U.S.
The fossil fuels used in energy generation are:Natural gas, which is 70 - 80% methane (CH4)
Liquid hydrocarbons obtained from the distillation of petroleum
Coal - a solid mixture of large molecules with a H/C ratio of about 1
Problems with Fossil FuelsProblems with Fossil FuelsFossil fuels are nonrenewable resources.
At projected consumption rates, natural gas and petroleum will be depleted before the end of the 21st century.
Impurities in fossil fuels are a major source of pollution.
Burning fossil fuels produce large amounts of CO2, which contributes to global warming.
1. Energy Resources
2. Oil2. Oil3. Natural Gas
4. Coal
5. Nuclear Energy
www.bio.miami.edu/beck/esc101/Chapter14&15.ppt
OilOilDeposits of crude oil often are trapped within
the earth's crust and can be extracted by drilling a well.
Fossil fuel, produced by the decomposition of deeply buried organic matter from plants and animals.
Crude oil: complex liquid mixture of hydrocarbons, with small amounts of S, O, N impurities.
How Oil Drilling Works by Craig C. Freudenrich, Ph.D. – read the entire article on science.howstuffworks.com.
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.
Oil in U.S.Oil in U.S.•2.3% of world reserves.
•Uses nearly 30% of world reserves.
•65% for transportation.
•Increasing dependence on imports.
Low oil prices have stimulated economic growth, they have discouraged/prevented improvements in energy efficiency and alternative technologies favoring renewable resources.
• Burning any fossil fuel releases carbon dioxide into the atmosphere and thus promotes global warming.
• Comparison of CO2 emitted by fossil fuels and nuclear power.
OilOilCrude oil is transported to a refinery
where distillation produces petrochemicals.
How Oil Refining Works by Craig C. Freudenrich, Ph.D.
1. Energy Resources
2. Oil
3. Natural Gas3. Natural Gas4. Coal
5. Nuclear Energy
www.bio.miami.edu/beck/esc101/Chapter14&15.ppt
Natural Gas - Fossil FuelNatural Gas - Fossil Fuel
• Mixture • 50–90% Methane (CH4)
• Ethane (C2H6)
• Propane (C3H8)
• Butane (C4H10)
• Hydrogen sulfide (H2S)
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%).
•90–95% of natural gas in U.S. domestic (~411,000 km = 255,000 miles of pipeline).
Natural GasNatural GasExperts predict increased use of natural gas
during this century.
Natural GasNatural GasWhen a natural gas field is tapped, propane
and butane are liquefied and removed as liquefied petroleum gas (LPG).
The rest of the gas (mostly methane) is dried, cleaned, and pumped into pressurized pipelines for distribution.
Liquefied natural gas (LNG) can be shipped in refrigerated tanker ships.
1. Energy Resources
2. Oil
3. Natural Gas
4. Coal4. Coal5. Nuclear Energy
www.bio.miami.edu/beck/esc101/Chapter14&15.ppt
Coal: Supply and DemandCoal: Supply and DemandCoal exists in many forms therefore a chemical
formula cannot be written for it.Coalification: After plants died they
underwent chemical decay to form a product known as peat.Over many years, thick peat layers formed. Peat is converted to coal by geological events such
as land subsidence which subject the peat to great pressures and temperatures.
Ranks of CoalRanks of Coal Anthracite : A hard, black lustrous coal, often referred to as hard
coal, containing a high percentage of fixed carbon and a low percentage of volatile matter. Energy content of about 14,000 Btu/lb.
Bituminous: Most common coal and is dense and black (often with well-defined bands of bright and dull material). Its moisture content usually is less than 20 percent. Energy content about 10,500 Btu / lb.
Subbituminous: Black lignite and is dull black and generally contains 20 to 30 percent moisture Energy content is 8,300 BTU/lb.
Lignite: A brownish-black coal of low quality (i.e., low heat
content per unit) with high inherent moisture and volatile matter. Energy content is lower than 4,000 BTU/lb.
PEATPEAT
LIGNITELIGNITE
BITUMINOUSBITUMINOUS
ANTHRACITEANTHRACITE
Main Coal DepositsMain Coal Deposits
BituminousBituminous
AnthraciteAnthracite
SubbituminousSubbituminous
LigniteLignite
garnero101.asu.edu/glg101/Lectures/L37.ppt
Advantages and DisadvantagesAdvantages and Disadvantages
Pros•Most abundant fossil fuel.•Major U.S. reserves.•300 years at current consumption rates.•High net energy yield.
Cons•Dirtiest fuel, highest carbon dioxide.•Major environmental degradation.•Major threat to health. © Brooks/Cole Publishing Company / ITP
Sulfur in CoalSulfur in CoalWhen coal is burned, sulfur is released
primarily as sulfur dioxide (SO2 - serious pollutant).
Coal Cleaning - Methods of removing sulfur from coal include cleaning, solvent refining, gasification, and liquefaction. Scrubbers are used to trap SO2 when coal is burned.
Two chief forms of sulfur are inorganic (FeS2 or CaSO4) and organic (Sulfur bound to Carbon).
CoalCoal Coal gasification Synthetic
natural gas (SNG)Coal liquefaction Liquid
fuelsDisadvantage
CostlyHigh Environmental Impact
1. Energy Resources
2. Oil
3. Natural Gas
4. Coal
5. Nuclear Energy5. Nuclear Energy
www.bio.miami.edu/beck/esc101/Chapter14&15.ppt
Nuclear EnergyNuclear EnergyIn a conventional nuclear
power plant:a controlled nuclear fission chain reaction
heats waterproduces high-pressure steam that turns turbines generates electricity.
Nuclear EnergyNuclear EnergyControlled Fission Chain Reaction
Neutrons split the nuclei of atoms such as of Uranium or Plutonium
Release energy (heat)
Controlled Nuclear Fission ReactionControlled Nuclear Fission Reaction
• Radioactive decay continues until the the original isotope is changed into a stable isotope that is not radioactive.
• Radioactivity: Nuclear changes in which unstable (radioactive) isotopes emit particles & energy.
RadioactivityRadioactivity
• Types• Alpha particles consist of 2 protons and 2 neutrons,
and therefore are positively charged• Beta particles are negatively charged (electrons)• Gamma rays have no mass or charge, but are a form
of electromagnetic radiation (similar to X-rays)
• Sources of natural radiation• Soil• Rocks• Air• Water• Cosmic rays
RadioactivityRadioactivity
Relative Doses from
Radiation Sources
The time needed for one-half of the nuclei in a radioisotope to decay and emit their radiation to form a different isotope.
Half-time emitted Uranium 235 710 million yrs alpha, gammaPlutonium 239 24.000 yrs alpha, gamma
During operation, nuclear power plants produce radioactive wastes, including some that remain dangerous for tens of thousands of years.
Half-LifeHalf-Life
Diagram of Radioactive Decay
• Genetic Damages: from mutations that alter genes.
• Genetic defects can become apparent in the next generation.
• Somatic Damages: to tissue, such as burns, miscarriages, and cancers.
Effects of RadiationEffects of Radiation
1. Low-level radiation (Gives off low amount of radiation.)
• Sources: nuclear power plants, hospitals, and universities.
• 1940 -1970 most was dumped into the ocean. • Today deposited into landfills.
2. High-level radiation (Gives off large amount of radiation.)
• Fuel rods from nuclear power plants.• Half-time of Plutonium 239 is 24,000 years.• No agreement about a safe method of storage.
Radioactive WasteRadioactive Waste
Radioactive WasteRadioactive Waste1. Bury it deep underground.
• Problems: i.e., earthquake, groundwater…2. Shoot it into space or into the sun.
• Problems: costs, accident would affect large area.3. Bury it under the Antarctic ice sheet.
• Problems: long-term stability of ice is not known, global warming.
4. Most likely plan for the US.• Bury it into Yucca Mountain in desert of Nevada.• Cost of over $ 50 billion.• 160 miles from Las Vegas.• Transportation across the country via train & truck.
Yucca Mountain
www.geology.fau.edu/course_info/fall02/ EVR3019/Nuclear_Waste.ppt
Plutonium BreedingPlutonium Breeding238U is the most plentiful isotope of
Uranium.Non-fissionable - useless as fuel.Reactors can be designed to convert
238U into a fissionable isotope of plutonium, 239Pu.
Conversion of Conversion of 238238U to U to 239239Pu Pu Under appropriate operating conditions, the neutrons given off by fission reactions can "breedbreed" more fuel, from otherwise non-fissionable isotopes, than they consume.
www.geology.fau.edu/course_info/fall02/ EVR3019/Nuclear_Waste.ppt
Reprocess Nuclear FuelReprocess Nuclear FuelDuring the operation of a nuclear
reactor the uranium runs out.Accumulating fission products
hinder the proper function of a nuclear reactor.
Fuel needs to be (partly) renewed every year.
Plutonium in Spent FuelPlutonium in Spent Fuel Spent nuclear fuel contains many
newly formed plutonium atoms. Miss out on the opportunity to split. Plutonium in nuclear waste can be
separated from fission products and uranium.
Cleaned Plutonium can be used in a different Nuclear Reactor.
Nuclear EnergyNuclear EnergyConcerns about the safety,
cost, and liability have slowed the growth of the nuclear power industry.
Accidents at Chernobyl and Three Mile Island showed that a partial or complete meltdown is possible.
Nuclear Power Plants in U.S.Nuclear Power Plants in U.S.
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.
ChernobylChernobyl• April 26, 1986, reactor explosion (Ukraine) flung radioactive debris into atmosphere.
• Health ministry reported 3,576 deaths.
• Green Peace estimates32,000 deaths.
• About 400,000 people were forced to leave their homes.
• ~160,000 sq km (62,00 sq mi) contaminated.
• > Half million people exposed to dangerous levels of radioactivity.
• Cost of incident > $358 billion.
Nuclear EnergyNuclear EnergyNuclear plants must be decommissioned
after 15-40 years.New reactor designs are still proposed.Experimental breeder nuclear fission
reactors have proven too costly to build and operate.
Attempts to produce electricity by nuclear fusion have been unsuccessful.
Use of Nuclear EnergyUse of Nuclear Energy• U.S. phasing out.• Some countries (France, Japan) investing is
increasing.• U.S. currently ~7% of energy is nuclear.• No new U.S. power plants ordered since 1978.• 40% of 105 commercial nuclear power plants
expected to be retired by 2015 and all by 2030.• North Korea is getting new plants from the US.• France has 78% of energy from nuclear.
Phasing Out Nuclear PowerPhasing Out Nuclear Power•Multi-billion-$$ construction costs
•High operation costs
•Frequent malfunctions
•False assurances and cover–ups
•Overproduction of energy in some areas
•Poor management
•Lack of public acceptance
EnergyEnergyEnergy & Energy & Mineral resourcesMineral resources