2TYPES OF ENERGY RESOURCES About 99% of the energy we use for heat comes from the sun and the other 1% comes mostly from burning fossil fuels.Solar energy indirectly supports wind power, hydropower, and biomass.About 76% of the commercial energy we use comes from nonrenewable fossil fuels (oil, natural gas, and coal) with the remainder coming from renewable sources.
3TYPES OF ENERGY RESOURCES Nonrenewable energy resources and geothermal energy in the earth’s crust.
4Floating oil drilling platform Coal Oil storage Geothermal energy Oil and natural gasFloating oil drilling platformCoalOil storageGeothermal energyContour strip miningOil drilling platform on legsHot water storageOil wellGas wellPipelineGeothermal power plantMined coalValvesArea strip miningPipelinePumpDrilling towerImpervious rockUnderground coal mineOilNatural gasWaterFigure 16.2Natural capital: important nonrenewable energy resources that can be removed from the earth’s crust are coal, oil, natural gas, and some forms of geothermal energy. Nonrenewable uranium ore is also extracted from the earth’s crust and processed to increase its concentration of uranium-235, which can serve as a fuel in nuclear reactors to produce electricity.Water is heated and brought up as dry steam or wet steamWaterWater penetrates down through the rockCoal seamHot rockMagma
5TYPES OF ENERGY RESOURCES Commercial energy use by source for the world (left) and the U.S. (right).
6Hydropower, geothermal, solar, wind WorldNuclear power 6%Hydropower, geothermal, solar, wind7%Natural gas21%RENEWABLE 18%Biomass 11%Coal 22%Figure 16.3Natural capital: commercial energy use by source for the world (left) and the United States (right) in Commercial energy amounts to only 1% of the energy used in the world; the other 99% is direct solar energy received from the sun and is not sold in the marketplace. (Data from U.S. Department of Energy, British Petroleum, Worldwatch Institute, and International Energy Agency)Oil 33%NONRENEWABLE 82%
7Hydropower geothermal, solar, wind 3% United StatesHydropower geothermal, solar, wind 3%Natural gas 23%Nuclear power 8%RENEWABLE 8%Coal 23%Biomass 4%Oil 39%Figure 16.3Natural capital: commercial energy use by source for the world (left) and the United States (right) in Commercial energy amounts to only 1% of the energy used in the world; the other 99% is direct solar energy received from the sun and is not sold in the marketplace. (Data from U.S. Department of Energy, British Petroleum, Worldwatch Institute, and International Energy Agency)NONRENEWABLE 93%
9TYPES OF ENERGY RESOURCES Net energy is the amount of high-quality usable energy available from a resource after subtracting the energy needed to make it available.
10Net Energy RatiosThe higher the net energy ratio, the greater the net energy available. Ratios < 1 indicate a net energy loss.
11Electric resistance heating (coal-fired plant) 0.4 Space HeatingPassive solar5.8Natural gas4.9Oil4.5Active solar1.9Coal gasification1.5Electric resistance heating (coal-fired plant)0.4Electric resistance heating (natural-gas-fired plant)0.4Electric resistance heating (nuclear plant)0.3High-Temperature Industrial HeatSurface-mined coal28.2Underground-mined coal25.8Natural gas4.9Oil4.7Coal gasification1.5Direct solar (highly concentrated by mirrors, heliostats, or other devices)Figure 16.4Science: Net energy ratios for various energy systems over their estimated lifetimes: the higher the net energy ratio, the greater the net energy available. QUESTION: Based on these data which three resources in each category should we be using? Compare this with the major resources we are actually using as shown in Figure (Data from U.S. Department of Energy and Colorado Energy Research Institute, Net Energy Analysis, 1976; and Howard T. Odum and Elisabeth C. Odum, Energy Basis for Man and Nature, 3rd ed., New York: McGraw-Hill, 1981)0.9TransportationNatural gas4.9Gasoline (refined crude oil)4.1Biofuel (ethyl alcohol)1.9Coal liquefaction1.4Oil shale1.2
12OILCrude oil (petroleum) is a thick liquid containing hydrocarbons that we extract from underground deposits and separate into products such as gasoline, heating oil and asphalt.Only 35-50% can be economically recovered from a deposit.As prices rise, about 10-25% more can be recovered from expensive secondary extraction techniques.This lowers the net energy yield.
13OIL Refining crude oil: Based on boiling points, components are removed at various layers in a giant distillation column.The most volatile components with the lowest boiling points are removed at the top.
14Gases Gasoline Aviation fuel Heating oil Diesel oil Naptha Figure 16.5Science: refining crude oil. Based on their boiling points, components are removed at various levels in a giant distillation column. The most volatile components with the lowest boiling points are removed at the top of the column.Heated crude oilGrease and waxFurnaceAsphalt
15OILEleven OPEC (Organization of Petroleum Exporting Countries) have 78% of the world’s proven oil reserves and most of the world’s unproven reserves.After global production peaks and begins a slow decline, oil prices will rise and could threaten the economies of countries that have not shifted to new energy alternatives.
17Oil price per barrel ($) Figure 16.6Economics: inflation-adjusted price of oil, 1950–2006. When adjusted for inflation, oil costs about the same as it did in Although low oil prices have stimulated economic growth, they have discouraged improvements in energy efficiency and use of renewable energy resources. QUESTIONS: Were you aware that when adjusted for inflation oil and gasoline do not cost much more today than in 1975? Is this desirable or undesirable from an environmental standpoint? Explain. (U.S. Department of Energy and Department of Commerce)(2006 dollars)Year
18Case Study: U.S. Oil Supplies The U.S. – the world’s largest oil user – has only 2.9% of the world’s proven oil reserves.U.S oil production peaked in 1974 (halfway production point).About 60% of U.S oil imports goes through refineries in hurricane-prone regions of the Gulf Coast.
19OILBurning oil for transportation accounts for 43% of global CO2 emissions.
20Trade-Offs Conventional Oil Advantages Disadvantages Ample supply for 42–93 yearsNeed to find substitutes within 50 yearsLow cost (with huge subsidies)Artificially low price encourages waste and discourages search for alternativesHigh net energy yieldEasily transported within and between countriesAir pollution when burnedFigure 16.7Trade-offs: advantages and disadvantages of using conventional crude oil as an energy resource. QUESTION: Which single advantage and which single disadvantage do you think are the most important?Low land useTechnology is well developedReleases CO2 when burnedEfficient distribution systemModerate water pollution
21CO2 EmissionsCO2 emissions per unit of energy produced for various energy resources.
22Coal-fired electricity 286% Synthetic oil and gas produced from coal150%100%Coal92%Oil sand86%OilFigure 16.8Natural capital degradation: CO2 emissions per unit of energy produced by using various energy resources to produce electricity, expressed as percentages of emissions produced by burning coal directly. These emissions can enhance the earth’s natural greenhouse effect (Figure 5-7, p. 104) and lead to warming of the troposphere. QUESTION: What three conclusions can you draw from these data? (Data from U.S. Department of Energy)58%Natural gasNuclear power fuel cycle17%10%Geothermal
23Heavy Oils from Oil Sand and Oil Shale: Will Sticky Black Gold Save Us? Heavy and tarlike oils from oil sand and oil shale could supplement conventional oil, but there are environmental problems.High sulfur content.Extracting and processing produces:Toxic sludgeUses and contaminates larges volumes of waterRequires large inputs of natural gas which reduces net energy yield.
24Oil ShalesOil shales contain a solid combustible mixture of hydrocarbons called kerogen.
25Heavy OilsIt takes about 1.8 metric tons of oil sand to produce one barrel of oil.
26Heavy Oils from Oil Shale and Oil Sand Trade-OffsHeavy Oils from Oil Shale and Oil SandAdvantagesDisadvantagesModerate cost (oil sand)High cost (oil shale)Large potential supplies, especially oil sands in CanadaLow net energy yieldLarge amountof water neededfor processingEasily transported within and between countriesSevere land disruptionFigure 16.10Trade-offs: advantages and disadvantages of using heavy oils from oil sand and oil shale as energy resources. QUESTION: Which single advantage and which single disadvantage do you think are the most important?Severe water pollutionEfficient distribution system in placeAir pollution when burnedTechnology is well developedCO2 emissions when burned
27NATURAL GASNatural gas, consisting mostly of methane, is often found above reservoirs of crude oil.When a natural gas-field is tapped, gasses are liquefied and removed as liquefied petroleum gas (LPG).Coal beds and bubbles of methane trapped in ice crystals deep under the arctic permafrost and beneath deep-ocean sediments are unconventional sources of natural gas.
28NATURAL GASRussia and Iran have almost half of the world’s reserves of conventional gas, and global reserves should last years.Natural gas is versatile and clean-burning fuel, but it releases the greenhouse gases carbon dioxide (when burned) and methane (from leaks) into the troposphere.
29NATURAL GASSome analysts see natural gas as the best fuel to help us make the transition to improved energy efficiency and greater use of renewable energy.
30Trade-Offs Conventional Natural Gas Advantages Disadvantages Ample supplies (125 years)Nonrenewable resourceHigh net energy yieldReleases CO2 when burnedLow cost (with huge subsidies)Methane (a greenhouse gas) can leak from pipelinesLess air pollution than other fossil fuelsLower CO2 emissions than other fossil fuelsDifficult to transfer from one country to anotherModerate environmental impactFigure 16.11Trade-offs: advantages and disadvantages of using conventional natural gas as an energy resource. QUESTION: Which single advantage and which single disadvantage do you think are the most important?Shipped across ocean as highly explosive LNGEasily transported by pipelineSometimes burned off and wasted at wells because of low priceLow land useGood fuel for fuel cells and gas turbinesRequires pipelines
31COALCoal is a solid fossil fuel that is formed in several stages as the buried remains of land plants that lived million years ago.
32Bituminous (soft coal) Anthracite (hard coal) Increasing heat and carbon contentIncreasing moisture contentPeat (not a coal)Lignite (brown coal)Bituminous (soft coal)Anthracite (hard coal)HeatHeatHeatPressurePressurePressurePartially decayed plant matter in swamps and bogs; low heat contentLow heat content; low sulfur content; limited supplies in most areasExtensively used as a fuel because of its high heat content and large supplies; normally has a high sulfur contentHighly desirable fuel because of its high heat content and low sulfur content; supplies are limited in most areasFigure 16.12Natural capital: stages in coal formation over millions of years. Peat is a soil material made of moist, partially decomposed organic matter. Lignite and bituminous coal are sedimentary rocks, whereas anthracite is a metamorphic rock (Figure 15-8, p. 343). QUESTION: Are there coal deposits near where you live or go to school?
33Increasing heat and carbon content Increasing moisture contentPeat(not a coal)Lignite(brown coal)Bituminous(soft coal)Anthracite(hard coal)HeatPressureHeatPressureHeatPressureHighly desirable fuel because of its high heat content and low sulfur content;supplies are limited in most areasPartially decayed plant matter in swamps and bogs; low heatcontentExtensively usedas a fuel becauseof its high heat content and large supplies; normally has ahigh sulfur contentLow heat content;low sulfur content; limited supplies in most areas
34Cooling tower transfers waste heat to atmosphere Coal bunker Turbine GeneratorCooling loopStackPulverizing millCondenserFilterFigure 16.13Science: Coal-burning power plant. Heat produced by burning pulverized coal in a furnace boils water to produce steam that spins a turbine to produce electricity. The steam is cooled, condensed, and returned to the furnace for reuse. A large cooling tower transfers waste heat to the troposphere. The largest coal-burning power plant in the United States in Indiana burns 23 metric tons (25 tons) of coal per minute or three 100-car trainloads of coal per day and produces 50% more electric power than the Hoover Dam. QUESTION: Is there a coal-burning power plant near where you live or go to school?BoilerToxic ash disposal
35COALCoal reserves in the United States, Russia, and China could last hundreds to over a thousand years.The U.S. has 27% of the world’s proven coal reserves, followed by Russia (17%), and China (13%).In 2005, China and the U.S. accounted for 53% of the global coal consumption.
36COALCoal is the most abundant fossil fuel, but compared to oil and natural gas it is not as versatile, has a high environmental impact, and releases much more CO2 into the troposphere.
37Trade-Offs Coal Advantages Disadvantages Ample supplies (225–900 years)Severe land disturbance, air pollution, and water pollutionHigh net energy yieldHigh land use (including mining)Low cost(with huge subsidies)Severe threat to human healthWell-developed mining and combustion technologyFigure 16.14Trade-offs: advantages and disadvantages of using coal as an energy resource. QUESTION: Which single advantage and which single disadvantage do you think are the most important?High CO2 emissions when burnedAir pollution can be reduced with improved technology (but adds to cost)Releases radioactive particles and toxic mercury into air
38COALCoal can be converted into synthetic natural gas (SNG or syngas) and liquid fuels (such as methanol or synthetic gasoline) that burn cleaner than coal.Costs are high.Burning them adds more CO2 to the troposphere than burning coal.
39COALSince CO2 is not regulated as an air pollutant and costs are high, U.S. coal-burning plants are unlikely to invest in coal gasification.
40Trade-Offs Synthetic Fuels Advantages Disadvantages Large potential supplyLow to moderate net energy yieldHigher cost than coalVehicle fuelRequiresmining 50%more coalModerate cost (with large government subsidies)High environmental impactFigure 16.15Trade-offs: advantages and disadvantages of using synthetic natural gas (syngas) and liquid synfuels produced from coal. QUESTION: Which single advantage and which single disadvantage do you think are the most important?Increased surface mining of coalLower air pollution when burned than coalHigh water useHigher CO2 emissions than coal
41NUCLEAR ENERGYWhen isotopes of uranium and plutonium undergo controlled nuclear fission, the resulting heat produces steam that spins turbines to generate electricity.The uranium oxide consists of about 97% nonfissionable uranium-238 and 3% fissionable uranium-235.The concentration of uranium-235 is increased through an enrichment process.
42Small amounts of radioactive gases Uranium fuel input (reactor core)Control rodsContainment shellHeat exchangerSteamTurbineGeneratorElectric powerWaste heatHot coolantUseful energy 25%–30%Hot water outputPumpPumpCoolantPumpPumpCool water inputWaste heatFigure 16.16Science: light-water–moderated and –cooled nuclear power plant with a pressurized water reactor. QUESTION: How does this plant differ from the coal-burning plant in Figure 16-13?ModeratorCoolant passageShieldingPressure vesselWaterCondenserPeriodic removal and storage of radioactive wastes and spent fuel assembliesPeriodic removal and storage of radioactive liquid wastesWater source (river, lake, ocean)
43NUCLEAR ENERGYAfter three or four years in a reactor, spent fuel rods are removed and stored in a deep pool of water contained in a steel-lined concrete container.
44NUCLEAR ENERGYAfter spent fuel rods are cooled considerably, they are sometimes moved to dry-storage containers made of steel or concrete.
45Decommissioning of reactor Fuel assemblies Enrichment of UF6Fuel fabrication(conversion of enriched UF6 to UO2 and fabrication of fuel assemblies)Temporary storage of spent fuel assemblies underwater or in dry casksConversion of U3O8 to UF6Uranium-235 as UF6 Plutonium-239 as PuO2Spent fuel reprocessingLow-level radiation with long half-lifeFigure 16.18Science: the nuclear fuel cycle. QUESTION: Are any parts of the nuclear fuel cycle within 27 kilometers (17 miles) of where you live or go to school?Geologic disposal of moderate & high-level radioactive wastesOpen fuel cycle today“Closed” end fuel cycle
46What Happened to Nuclear Power? After more than 50 years of development and enormous government subsidies, nuclear power has not lived up to its promise because:Multi billion-dollar construction costs.Higher operation costs and more malfunctions than expected.Poor management.Public concerns about safety and stricter government safety regulations.
47Case Study: The Chernobyl Nuclear Power Plant Accident The world’s worst nuclear power plant accident occurred in 1986 in Ukraine.The disaster was caused by poor reactor design and human error.By 2005, 56 people had died from radiation released.4,000 more are expected from thyroid cancer and leukemia.
49NUCLEAR ENERGYIn 1995, the World Bank said nuclear power is too costly and risky.In 2006, it was found that several U.S. reactors were leaking radioactive tritium into groundwater.
50Cannot compete economically without huge government subsidies Trade-OffsConventional Nuclear Fuel CycleAdvantagesDisadvantagesLarge fuel supplyCannot compete economically without huge government subsidiesLow environmental impact (without accidents)Low net energy yieldHigh environmental impact (with major accidents)Emits 1/6 as much CO2 as coalModerate land disruption and water pollution (without accidents)Catastrophic accidents can happen (Chernobyl)No widely acceptable solution for long-term storage of radioactive wastes and decommissioning worn-out plantsFigure 16.19Trade-offs: advantages and disadvantages of using the conventional nuclear fuel cycle (Figure 16-18) to produce electricity. QUESTION: Which single advantage and which single disadvantage do you think are the most important?Moderate land useLow risk of accidents because of multiple safety systems (except for 15 Chernobyl-type reactors)Subject to terrorist attacksSpreads knowledge and technology for buildingnuclear weapons
51NUCLEAR ENERGYA 1,000 megawatt nuclear plant is refueled once a year, whereas a coal plant requires 80 rail cars a day.
52Ample supply of uranium Trade-OffsCoal vs. NuclearCoalNuclearAmple supplyAmple supply of uraniumLow net energy yieldHigh net energy yieldLow air pollution (mostly from fuel reprocessing)Very high air pollutionHigh CO2 emissionsLow CO2 emissions (mostly from fuel reprocessing)High land disruption from surface miningFigure 16.20Trade-offs: comparison of the risks of using nuclear power and coal-burning plants to produce electricity. A 1,000-megawatt nuclear plant is refueled once a year, whereas a coal plant of the same size requires 80 rail cars of coal a day. QUESTION: If you had to, would you rather live next door to a coal-fired power plant or a nuclear power plant? Explain.Much lower land disruption from surface miningHigh land useModerate land useLow cost (with huge subsidies)High cost (even withhuge subsidies)
53NUCLEAR ENERGYTerrorists could attack nuclear power plants, especially poorly protected pools and casks that store spent nuclear fuel rods.Terrorists could wrap explosives around small amounts of radioactive materials that are fairly easy to get, detonate such bombs, and contaminate large areas for decades.
54NUCLEAR ENERGYWhen a nuclear reactor reaches the end of its useful life, its highly radioactive materials must be kept from reaching the environment for thousands of years.At least 228 large commercial reactors worldwide (20 in the U.S.) are scheduled for retirement by 2012.Many reactors are applying to extent their 40-year license to 60 years.Aging reactors are subject to embrittlement and corrosion.
55NUCLEAR ENERGYBuilding more nuclear power plants will not lessen dependence on imported oil and will not reduce CO2 emissions as much as other alternatives.The nuclear fuel cycle contributes to CO2 emissions.Wind turbines, solar cells, geothermal energy, and hydrogen contributes much less to CO2 emissions.
56NUCLEAR ENERGYScientists disagree about the best methods for long-term storage of high-level radioactive waste:Bury it deep underground.Shoot it into space.Bury it in the Antarctic ice sheet.Bury it in the deep-ocean floor that is geologically stable.Change it into harmless or less harmful isotopes.
57New and Safer ReactorsPebble bed modular reactor (PBMR) are smaller reactors that minimize the chances of runaway chain reactions.
58Reactor vessel Water cooler Each pebble contains about 10,000 uranium dioxide particles the size of a pencil point.Pebble detailSilicon carbidePyrolytic carbonPorous bufferUranium dioxideGraphite shellHeliumTurbineGeneratorPebbleFigure 16.21Pebble bed modular reactor (PBMR): this is one of several new and smaller reactor designs that some nuclear engineers say should improve the safety of nuclear power and reduce its costs. This design reduces chances of a runaway chain reaction by encapsulating uranium fuels in tiny heat-resistant ceramic spheres instead of packing large numbers of fuel pellets into long metal rods.Hot water outputCoreCool water inputReactor vesselRecuperatorWater cooler
59New and Safer Reactors Some oppose the pebble reactor due to : A crack in the reactor could release radioactivity.The design has been rejected by UK and Germany for safety reasons.Lack of containment shell would make it easier for terrorists to blow it up or steal radioactive material.Creates higher amount of nuclear waste and increases waste storage expenses.
60NUCLEAR ENERGYNuclear fusion is a nuclear change in which two isotopes are forced together.No risk of meltdown or radioactive releases.May also be used to breakdown toxic material.Still in laboratory stages.There is a disagreement over whether to phase out nuclear power or keep this option open in case other alternatives do not pan out.