Chapter 12Chapter 12Renewable EnergyRenewable Energy

Heating Buildings and WaterHeating Buildings and Water

Passive solar energy- no machines Passive solar energy- no machines usedused

Heating Buildings and WaterHeating Buildings and Water

Active Solar EnergyActive Solar Energy Collecting and absorbing the sun’s energy, and using Collecting and absorbing the sun’s energy, and using

pumps or fans distribute heat pumps or fans distribute heat Ex:Ex:

Large solar plants- can create very hot environments Large solar plants- can create very hot environments overhead and can incinerate animals that fly over.overhead and can incinerate animals that fly over.

Solar Thermal Electric Generation

Photovoltaic Solar Cells

BiomassBiomass

AdvantagesAdvantages Reduces dependence on fossil fuelsReduces dependence on fossil fuels Often uses waste materialsOften uses waste materials Can be Can be renewablerenewable

DisadvantagesDisadvantages Requires land, water and fossil fuel Requires land, water and fossil fuel

energyenergy Can lead to Can lead to

DeforestationDeforestation DesertificationDesertification Soil erosionSoil erosion

Wind EnergyWind Energy

No waste - clean No waste - clean source of energysource of energy

Biggest Biggest constraints:constraints: Cost Cost Public resistance Public resistance

(NIMBY)(NIMBY)

Few environmental problems Few environmental problems Kills birds and batsKills birds and bats

HydropowerHydropower

Hydrogen as a Fuel SourceHydrogen as a Fuel Source

Hydrogen gas (HHydrogen gas (H22)) Comprised of two hydrogen moleculesComprised of two hydrogen molecules Large amounts of available energyLarge amounts of available energy Explodes when combined with oxygen Explodes when combined with oxygen

releasing energy and forming waterreleasing energy and forming water

Geothermal and Tidal Geothermal and Tidal EnergyEnergy Other forms of renewable energy Other forms of renewable energy

(not from solar)(not from solar) Geothermal energy- energy from the Geothermal energy- energy from the

Earth’s interiorEarth’s interior Tidal energy- relies on ebb and flow of Tidal energy- relies on ebb and flow of

the tidesthe tides

Energy Savings in Energy Savings in Commercial BuildingsCommercial Buildings

Saving Energy at HomeSaving Energy at Home

Atoms and RadioactivityAtoms and Radioactivity

Nucleus Nucleus Comprised of Comprised of

protons (+) and protons (+) and neutrons (neutral)neutrons (neutral)

Electrons (–) orbit Electrons (–) orbit around nucleusaround nucleus

Introduction to Nuclear Introduction to Nuclear EnergyEnergy Nuclear energyNuclear energy

Energy released by nuclear fission or fusionEnergy released by nuclear fission or fusion Nuclear fissionNuclear fission

Splitting of an atomic nucleus into two Splitting of an atomic nucleus into two smaller fragments, accompanied by the smaller fragments, accompanied by the release of a large amount of energyrelease of a large amount of energy

Nuclear fusionNuclear fusion Joining of two lightweight atomic nuclei into Joining of two lightweight atomic nuclei into

a single, heavier nucleus, accompanied by a single, heavier nucleus, accompanied by the release of a large amount of energy the release of a large amount of energy

Radioactive IsotopeRadioactive Isotope

Unstable isotopeUnstable isotope Radioactive DecayRadioactive Decay

Emission of energetic particles or rays Emission of energetic particles or rays from unstable atomic nucleifrom unstable atomic nuclei

ExampleExample Uranium (U-235) decays over time to Uranium (U-235) decays over time to

lead (Pb-207)lead (Pb-207) Each isotope decays based on its Each isotope decays based on its

own half-lifeown half-life

Radioactive Isotope Half-Radioactive Isotope Half-liveslives

Nuclear FissionNuclear Fission

How Electricity is ProducedHow Electricity is Produced

Pros and Cons of Nuclear Pros and Cons of Nuclear EnergyEnergy ProsPros

Less of an immediate environmental Less of an immediate environmental impact compared to fossil fuelsimpact compared to fossil fuels

Carbon-free source of electricityCarbon-free source of electricity May be able to generate H-fuelMay be able to generate H-fuel

ConsCons Generates radioactive wasteGenerates radioactive waste Many steps require fossil fuels (mining Many steps require fossil fuels (mining

and disposal)and disposal) ExpensiveExpensive

Pros and Cons of Nuclear Pros and Cons of Nuclear EnergyEnergy

Cost of Electricity from Cost of Electricity from Nuclear EnergyNuclear Energy

Cost is very highCost is very high 20% of US electricity is from Nuclear 20% of US electricity is from Nuclear

EnergyEnergy Affordable due to government subsidiesAffordable due to government subsidies

Expensive to build nuclear power Expensive to build nuclear power plantsplants

Fixing technical and safety issues in Fixing technical and safety issues in existing plants is expensiveexisting plants is expensive

Safety Issues in Nuclear Safety Issues in Nuclear Power PlantsPower Plants

MeltdownMeltdown At high temperatures the metal encasing At high temperatures the metal encasing

the uranium fuel can melt, releasing the uranium fuel can melt, releasing radiation radiation

Probability of meltdown is lowProbability of meltdown is low Public perception is that nuclear power Public perception is that nuclear power

is not safeis not safe Sites of major accidents:Sites of major accidents:

Three Mile IslandThree Mile Island Chornobyl (Ukraine)Chornobyl (Ukraine)

ChornobylChornobyl

1986 - worst 1986 - worst accident in accident in historyhistory Large amounts of Large amounts of

radiation escaped radiation escaped into atmosphereinto atmosphere

ChornobylChornobyl

Radiation spread was unpredictable Radiation spread was unpredictable and unevenand uneven

Radioactive WastesRadioactive Wastes

Long term solution to Long term solution to wastewaste Deep geologic burial – Deep geologic burial –

Yucca MountainYucca Mountain As of 2004, site must As of 2004, site must

meet EPA million year meet EPA million year standard standard

Radioactive WasteRadioactive Waste

Temporary storage solutionsTemporary storage solutions In nuclear plant facility (require high In nuclear plant facility (require high

security)security) Under water storageUnder water storage Above ground concrete and steel casksAbove ground concrete and steel casks

Need approved permanent options Need approved permanent options soon.soon.