Chapter 15 Geologic Resources: Nonrenewable Mineral and Energy Resources

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<ul><li><p>Chapter 15Geologic Resources: Nonrenewable Mineral and Energy Resources</p></li><li><p>Key QuestionWhat are nonrenewable mineral resources and how are they formed?How do we find and extract nonrenewable mineral and energy resources from the earths crust?How fast are mineral supplies being used up?How should we evaluate energy alternatives?What are advantages and disadvantages of natural gas?</p></li><li><p>What are Mineral Resources?Concentration of naturally occurring material in or on the earths crust that can be extracted and processed into useful materialsClassified as nonrenewable resources because they take so long to produceWe know how to find and extract 100+ nonrenewable minerals from the earths crust</p></li><li><p>We can extractMetallic mineral resources (iron, copper, aluminum)Nonmetallic mineral resources (salt, clay, sand, phosphates, soil)Energy resources (coal, oil, natural gas, uranium)</p></li><li><p>OreRock containing enough of 1+ metallic minerals to be mined for profitWe convert 40 metals extracted from ores into everyday items that are either 1) used and thrown away OR 2) reused or recycled</p></li><li><p>Categories of nonrenewable mineral resourcesUS Geological Survey divides nonrenewable mineral resource into categories:Identified resources: deposits of nonrenewable mineral resource with a known location and quantityUndiscovered resources: potential supplies assumed to exist in theoryReserves: identified resources from which resource can be extracted for profitOther resources: identified and discovered but not classified as reserves </p></li><li><p>How do ores form from magma?Ores form as a result of internal and external geologic processesPlate tectonics shape the earths crust and determine where the richest mineral deposits are found</p></li><li><p>As magma cools, it crystallizes into mineral-containing igneous rocks</p><p>Ore deposits form through hydrothermal processes</p><p>Upwelling magma solidifies into black smokers</p><p>Shoots out mineral-rich hot water on the seafloor</p><p>Minerals accumulate as hot and cold water contact</p><p>Form ore deposits rich in copper, lead, zinc, silver, and gold</p></li><li><p>Finding nonrenewable resourcesAerial photos and satellite imagesPlanes that detect deposits of radioactive metalsGravimeter to measure differences in density (ore differs from surrounding rock)Drilling deep well and extracting core samplesSeismic surveys by explosions and analyzing shock wavesChemical analysis of water and plants (absorb minerals)</p></li><li><p>Mining techniques (once resources have been found)Surface mining: equipment strips outer layer of soil and rock; in US, used to extract 90% nonfuel resources and 60% coalOpen-pit mining: machines dig holes and remove oresDredging: chains scrape underwater mineral depositsArea strip mining: parallel strips made in flat land; power shovels usedContour strip mining: terraces cut into side of hill; power shovels usedMountaintop removal: explosives used to remove top of mountain and expose coal underneath</p></li><li><p>Open Pit Mine</p></li><li><p>Dredging</p></li><li><p>Area Strip Mining</p></li><li><p>Contour Strip Mining</p></li><li><p>Surface Mining Control and Reclamation Act of 1977Requires mining companies to restore surface-mined land so that it is usable againAlthough surface-mined land can be restored, it is expensive and not done in many countries</p></li><li><p>Subsurface miningUsed to remove coal and other metal ores that are too deep to be extracted by surface miningBlast tunnels to get to deposit, use machinery to transport ore to the surfaceDisturbs 1/10 as much land as surface mining, produces less wasteMore dangerous and expensive </p></li><li><p>Environmental Effects of Extracting Mineral ResourcesFig. 15-6 p. 343</p></li><li><p>Percolation to groundwaterLeaching of toxic metalsand other compoundsfrom mine spoilAcid drainage fromreaction of mineralor ore with waterSpoil banksRunoff ofsedimentSurface MineSubsurfaceMine OpeningLeaching may carryacids into soil andgroundwater suppliesAcid mine drainage-pollution and degradationby acid runoff and toxic chemicals from mining-can kill fish and other aquatic life</p></li><li><p>Surface miningMetal oreSeparationof ore frommachineScattered in environmentRecyclingDiscarding of productConversion to productMelting metalSmelting</p></li><li><p>Processes involved in extractionSmelting: used to separate metal from other elements in the oreEnormous amount of pollution which damages surrounding vegetation and soilSmelters also produce liquid and hazardous waste that must be disposed of safely </p></li><li><p>Are there environmental limits?Resource experts believe that the greatest danger from increasing consumption of nonrenewable resources is environmental damage caused by extraction and processing.More accessible and high-grade ores are exploited firstIt takes more $ to exploit the deeper ores, causing more environmental effects</p></li><li><p>Will there be enough mineral resources?Future of nonrenewable minerals depends on: actual supply and rate at which supply is usedEconomic depletion: cost more to find, extract, transport and process than its worthDepletion time: time it takes to use up a 80% of nonrenewable resource</p></li><li><p>Supplies of mineral resourcesReserve-to-production ratio: number of years that reserves of a NM will lastMaterials revolution: new materials (ceramics and plastics) are being developed as replacements for metalsSubstitutes cannot be found for many mineral resources</p></li><li><p>Mined coalPipelinePumpOil wellGas wellOil storageCoalOil and Natural GasGeothermal EnergyHot waterstorageContourstrip miningPipelineDrillingtowerMagmaHot rockNatural gasOilImpervious rockWaterWaterOil drillingplatformon legsFloating oil drillingplatformValvesUndergroundcoal mineWater is heatedand brought upas dry steam orwet steamWaterpenetratesdownthroughtherockArea stripminingGeothermalpower plant</p></li><li><p>Energy usage99% of the energy used to heat the earth and our buildings comes from the sunWithout this input, earth would be -400 degrees F!</p></li><li><p>The other 1%?is commercial energy: from extracting and burning nonrenewable mineral resources from earths crust (mainly, fossil fuels-oil, natural gas, coal)A typical citizen of the US uses 65-140x as much energy per day as a hunter-gatherer</p></li><li><p>PrimitiveHuntergathererEarlyagriculturalAdvancedagriculturalEarlyindustrialModern industrial(other developednations)Modern industrial(United States)SocietyKilocalories per Person per Day260,000130,00060,00020,00012,0005,0002,000</p></li><li><p>OilUse of oil climbs by 1%/yearProjected to peak between 2010 and 2030 and then begin to declineNatural gas is increasing by 2%/year; cleanest and least disrupting of the 3 fossil fuelsBiomass: main source for heating in developing countries; renewable energy (fuelwood) BUT fuelwood shortage is a problem </p></li><li><p>What is oil?Petroleum (crude oil): thick liquid with hundreds of hydrocarbons with sulfur, nitrogen, and oxygen impuritiesCalled oil when it comes out of the groundFossil fuelProduced by the decomposition of dead plant matter that was 1) buried under lake and ocean sediments millions of years ago and 2) subjected to high temp and pressure for millions of years in the carbon cycle.</p></li><li><p>How is oil extracted?Deposits are trapped under the earths crust on land or under the seafloor in rock formationsWell is drilledOil is pumped out of the rock poresTransported to refinery by pipeline, truck, or oil tanker (ship) and separated into different typesDrilling always involves: 1) some oil spills 2) use of nonrenewable resource</p></li><li><p>Diesel oilAsphaltGreaseand waxHeating oilAviation fuelGasolineGasesFurnace</p></li><li><p>Who has the worlds oil supplies?Oil reserves: identified deposits where oil can be extractedSaudi Arabia has most oil reserves: 26%, then Iraq, Kuwait, Iran (each with about 10%)3% in U.S.</p></li><li><p>Oil in U.S.3% of all oil reserves in U.S.25% from offshore drilling17% from Alaskas North SlopeCurrently, 93% of offshore drilling comes from Gulf of Mexico</p></li><li><p>MEXICOUNITED STATESCANADAPacificOceanAtlanticOceanGrandBanksGulf ofAlaskaValdezALASKABeaufortSeaPrudhoe BayArcticOceanCoalGasOilHigh potentialareas</p></li><li><p>How long will oil supplies last?We are currently running out of oilSupplies decline when 1) demand exceeds production and 2) other energy resources become more environmentally acceptable substitutesProduction expected to peak between 2010 and 2030</p></li><li><p>ContinuedGlobal reserves will last about 50 years at current usage rateU.S. reserves will last about 10-20 years at current usage rateU.S. oil supplies are projected to be 80% depleted within 10-15 years</p></li><li><p>TEXASLOUISIANAMISSISSIPPIALABAMAGEORGIAFLORIDAGULF OF MEXICOActive drilling sites</p></li><li><p>Natural GasMixture of methane, propane, butane, highly toxic hydrogen sulfideConventional natural gas: lies above oil reserves, formed from fossils of plants (like oil), buried deep in seafloorUnconventional natural gas: found by itself in other underground sources (ex. Small bubbles trapped in ice crystals under arctic permafrost)very expensive to remove, but technology being developed</p></li><li><p>Who has natural gas supplies?Russia and Kazakhstan: 42%Other countries with large reserve: Iran, Saudi Arabia, Algeria, U.S. (3%)Geologists expect to find more natural gas reservesIn U.S. natural gas reserves are located in same place as crude oil </p></li><li><p>AdvantagesDisadvantagesGood fuel forfuel cells andgas turbinesLow land use</p><p>Easily transportedby pipeline</p><p>Moderate environ-mental impactLower CO2 emissions thanother fossil fuelsLess air pollutionthan otherfossil fuels</p><p>Low cost (withhuge subsidies)High net energyyieldAmple supplies(125 years)</p><p>Sometimes burned off andwasted at wellsbecause of lowpriceShipped acrossocean as highlyexplosiveMethane(a greenhouse gas) can leakfrom pipelinesReleases CO2when burnedNonrenewableresourceDifficult to transferfrom one countryto anotherRequirespipelines</p></li><li><p>How long will natural gas supplies last?Globally, 120 years at current consumption rateIn U.S., 60-75 years at current consumption rate</p></li><li><p>Pros and Cons?Natural gas systems (combustion turbines bolted to the ground): 1) produce electricity more efficiently than burning oil or nuclear power 2) Produce much less carbon dioxide 3) Provide backup for solar and wind power </p></li><li><p>How much do we use natural gas?Used in 53% of U.S. homes for heat16% of U.S. electricityBy 2020, it will be 32% of U.S. electricity</p></li><li><p>FrackingDrill into reservoir rock formations. The energy from the injection of a highly-pressurized fracking fluid creates new channels in the rockThis increases the extraction rates and the recovery of fossil fuelsCan cause leak of natural gas into groundwatervery toxic!Requires TONS of water, carcinogenic chemicals, etc.</p></li><li><p>What is COAL?Solid fossil fuel formed in several stages as buried remains of plants (300-400 mill years ago) were subjected to high heat and pressureCoal contains: sulfur, trace amts of mercury and radioactive materialsAnthracite is the most desirable form of coal because of low sulfur content and high heat </p></li><li><p>How is it extracted?Some is extracted underground by miners working in tunnelsArea strip mining: when coal lies close to the earths surface on flat terrainContour strip mining: when coal lies close to the earths surface on hilly terrainTransported to processing plant where it is broken up, crushed, and washed to remove impuritiesDried and shipped to power plants and industrial plants</p></li><li><p>Where are the largest coal supplies?Coal provides 21% of the worlds energyBurned to generate 62% of the worlds electricity66% of the worlds coal reserves are in U.S., Russia, China, and India.Half of the global coal consumption takes place in China and U.S.</p></li><li><p>How long will coal supplies last?Coal is the worlds most abundant fossil fuelReserves should last at least 220 years</p></li><li><p>Increasing moisture contentIncreasing heat and carbon contentPeat(not a coal)Lignite(brown coal)Bituminous Coal(soft coal)Anthracite(hard coal)HeatPressurePressurePressureHeatHeatPartially decayedplant matter in swampsand bogs; low heatcontentLow heat content;low sulfur content;limited supplies inmost areasExtensively usedas a fuel becauseof its high heat contentand large supplies;normally has ahigh sulfur contentHighly desirable fuelbecause of its highheat content andlow sulfur content;supplies are limitedin most areas</p></li><li><p>AdvantagesDisadvantagesLow costHigh net energyyieldAmple supplies(220895 years)Releases radioactive particles and mercury into airHigh CO2 emissionswhen burnedSevere threat tohuman healthHigh land use (including mining)</p><p>Severe land disturbance, air pollution, andwater pollutionVery high environmentalimpactMining andcombustiontechnologywell-developedAir pollution canbe reduced withimprovedtechnology (butadds to cost)</p></li><li><p>Nuclear PowerU.S. companies started developing nuclear power plants in the 1950s because:Atomic Energy Commission promised nuclear power would produce electricity at much lower costGovernment paid of the cost of building first group of reactorsPrice-Anderson Act: protects industry from public liability in case of accidents</p></li><li><p>Front endBack endUranium mines and millsOre and ore concentrate (U3O8)Geologic disposalof moderate-and high-levelradioactive wastesHigh-levelradioactivewasteUranium tailings(low level but long half-life)Conversion of U3O8to UF6Processeduranium oreUranium-235 as UF6Enrichment UF6EnrichedUF6Fuel fabricationSpent fuelreprocessingPlutonium-239as PuO2(conversion of enriched UF6 to UO2and fabrication of fuel assemblies)Fuel assembliesReactorSpent fuel assembliesInterim storageunder waterOpen fuel cycle todayProspective closed end fuel cycleNuclear Fuel Cycle</p></li><li><p>Figure 15-37Page 368OperationalDecommissionedProposed high levelnuclear waste storage siteReactors12</p></li><li><p>Low risk of accidents because of multiple safety systemsModerate land useModerate landdisruption andwater pollutionEmits 1/6 asmuch CO2 as coalLowenvironmentalimpact (withoutaccidents)Large fuelsupplySpreads knowledge and technology for building nuclear weaponsNo acceptable solution for long-term storage of radioactive wastesCatastrophic accidents can happen High environmental impact (with major accidents)Low net energy yieldHigh costAdvantagesDisadvantagesNuclear Power</p></li><li><p>CoalAmple supply</p><p>High net energyyieldVery high airpollutionHigh CO2emissions65,000 to 200,000deaths per yearin U.S.High land disruption fromsurface miningHigh land useLow cost)NuclearAmple supplyof uraniumLow net energyyield</p><p>Low air pollution</p><p>Low CO2emissionsAbout 6,000deaths per year in U.S.</p><p>Much lower landdisruption fromsurface miningModerate land use</p><p>High cost)COAL vs. NUCLEAR POWER</p></li><li><p>What should we do with high-level radioactive waste?Proposals:Bury it deep underground (not sure about long-term behavior of sites)Shoot it into space or into the sun (very high cost and if accident occurred, waste could be dispersed all over earth)Bury it under ice caps (long-term stability of ice caps is not known)Dump it into deep ocean (waste might be spewed out somewhere else by volcanic activity)</p></li><li><p>Connection between nuclear reactors and spread of nuclear weapons?60 countries (1 out of 3) have nuclear weapons or knowledge to build themInfo for this has come mostly from the U.S. which has been selling in international marketplaceBad news: enough nuclear weapons to kill everyone in the world 30xdirty bombs: dynamite mixed with radioactive material (easy to obtai...</p></li></ul>


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