World Energy and Their Sources

World Energy and Their SourcesNonrenewable Energy SourcesEnergySourceR/NRCrude OilLiquid fossil fuelNRNatural GasGas f.f.NRCoalSolid f.f.NRNuclear energyUranium nucleiNREnergySourceR/NRBiomassPlant matter (photosynthesis)RHydropowerRunning waterRSolar EnergySunlight RWind energyWindREnergySourceR/NRGeothermalInternal circulationRTidal & WaveTidal forces and ocean wavesRHydrogen fuel cellsWater RSolar Radiation drives Where do fossil fuels come from?

Where Does the Energy Go?DevelopingDevelopedENERGY TO MAKE ENERGY!To get fossil fuels and extract the energy from them, one mustNet Energy = Energy returned Energy invested

EROI: Energy Returned On InvestmentEROI=Energy returnedEnergy invested EROI:Presently, fossil fuels have:EROI can change over time:

Where Our Energy Comes Fromcoal

Coal FormationCoalMost abundant fossil fuelIt is the remains of mostly woody plant material from 300-400 MYA; little decomposition has occurred of coal in USCoal provides of worlds energyUS & China are main producers and consumersCoal: ImpuritiesSulfur can lead to acid rainMercury can bioaccumulateCoal: MiningSubsurface - shafts and tunnels into groundDangerous to minersCollapse of tunnelsBlack lung disease

Coal: MiningStrip Mining machines removes soil to expose coalHabitat destructionSoil erosionAcid drainage: sulfide minerals in rock react with O2 and H2O sulfuric acidAcid leaches out metals from rocks

Coal: MiningMountaintop removal is an extreme form of surface miningLoss of habitatBig soil erosionAdvantagesDisadvantagesEnergy-denseContains impuritiesPlentifulRelease impurities into air when burnedEasy to exploit by surface miningTrace metals like mercury, lead, and arsenic are found in coalTechnological demands are smallCombustion leads to increased levels of sulfur dioxide and other air pollutants into the atmosphere.Economic costs are lowAsh is left behindEasy to handle and transportCarbon is released into the atmosphere which contributes to climate changeNeeds little refiningPros and Cons of Coal

Coal-fired Power PlantNatural gasNatural GasCommercial energyProvides of global energyCleaner than coalLongevity: 60 yearsBiogenic GasAlso known as swamp gas shallow water decompositionPure methaneLandfill gas now is collected and used

Thermogenic GasFormed through heat and compression deep undergroundCoalbed methane is now being collectedWith oil too expensive to capture; burned at the sourceLNG liquefied natural gas easier to ship, but very dangerousEnvironmental ImpactsInfrastructure roads, housing, pipelines, soil removal, ponds to collect toxic sludgeMost drilling occurs in sensitive ecosystems arctic & semi-arid tundraExploratory workHydraulic fracturing has its own sets of problemsAdvantagesDisadvantagesContains fewer impurities and therefore emits almost no sulfur dioxide or particulatesWhen unburned, methane escapes into the atmosphereEmits only 60% as much carbon dioxide as coalExploration of natural gas has the potential of contaminating groundwaterPros and Cons of Natural GasCrude oil

OilWhat it is: a mixture of hydrocarbons with varying numbers of carbon atomsRefineries separate the hydrocarbons based upon differing boiling points (fractional distillation)

Fractional DistillationOil: ProspectingDrilling rock cores, all kinds of surveysAssess technically recoverable oilAssess economically recoverable oilProven Recoverable Reserve amt of fuel in a deposit that is technically & economically feasibleOil: DrillingPrimary extractionInitial drilling and pumpingGets out about 1/3 of the oilSecondary ExtractionGets out the remaining 2/3 of oilSolvents are needed$Oil: ImpactsSame impacts as with NGANWR is a big debateAdvantagesDisadvantagesConvenient to transport and useReleases carbon dioxide into atmosphereRelatively energy-densePossibility of leaks when extracted and transportedCleaner-burning than coalReleases sulfur, mercury, lead, and arsenic into the atmosphere when burned

Pros and Cons of OilOther Fossil FuelsOil sandsTar-like heavy oil in sand, clay; bitumenOil shaleSedimentary rock full of kerogen, a waxy mixture of HCsMethane hydrateMethane in ice; difficult to extractnuclear

Nuclear FissionFissionNuclear energy = energy holding protons and neutrons togetherNuclear energy thermal energy electricityIn fission, a large, unstable nucleus (U-235 or U-238), is made to break apart, releasing energyRadioisotopes are atoms of a certain element that emit subatomic particles and radiation to become stable

FissionEach radioisotope has a certain half-life of decayHalf-life is the time it takes for half of the original amount of radioactive isotope to decayAfter several years, rods must be replaced due to decay and consumptionFuel rods can be processed to extract more energy, but they are usually disposed of as radioactive waste

Nuclear Reactor DesignFusionFusion involves the synthesis of heavier elements from lighter ones under high temperature and pressureHydrogen isotopes (deuterium and tritium) are fused to form heliumHave not achieved break-even energyEnergy is cleaner, resources are plentiful (water)

Small Risks of Large Accidents1979 Three Mile Island in PennsylvaniaMetal surrounding the fuel rods melted down, releasing radiationIt did not escape containment (some gases were vented)Clean-up lasted yearsNo significant health risks

Small Risks of Large Accidents1986 an explosion at the Chernobyl plant (Ukraine) caused most severe nuclear pp disaster in the worldClouds of radioactive debris spewed into the atmosphereFallout carried over most of northern hemisphere30-km radius contaminated

Waste Disposal & Other ProblemsWaste remains dangerous for thousands of years (remember half-life?)Currently, waste is held in temporary storage on-siteYucca mountain in Nevada has been chosen for storage beginning in 2010More expensive than expectedPlants have aged more quicklyShutting down plants more expensive than the original construction

AdvantagesDisadvantagesNo air pollution is producedPossibility of accidentsCountries can limit their need for imported oilDisposal of the radioactive wastePros and Cons of Nuclear