Chapter 13Chapter 13Renewable Energy and ConservationRenewable Energy and Conservation

Overview of Chapter 13Overview of Chapter 13o Direct Solar EnergyDirect Solar Energy

• Heating Buildings and WaterHeating Buildings and Water• Solar Thermal Electric GenerationSolar Thermal Electric Generation• Photovoltaic Solar CellsPhotovoltaic Solar Cells

o Indirect Solar EnergyIndirect Solar Energy• Biomass EnergyBiomass Energy• Wind EnergyWind Energy• HydropowerHydropower

o Other Renewable Energy SourcesOther Renewable Energy Sources• Geothermal EnergyGeothermal Energy• Tidal EnergyTidal Energy

o High and Low Technology Energy SolutionHigh and Low Technology Energy Solution• Hydrogen and Fuel CellsHydrogen and Fuel Cells

o Energy EfficiencyEnergy Efficiency

Direct Solar EnergyDirect Solar Energyo Varies with latitude, season, time of Varies with latitude, season, time of

day, and cloud coverday, and cloud cover

Heating Buildings and WaterHeating Buildings and Water

o Passive solar energyPassive solar energy• system of putting the sun’s energy to use system of putting the sun’s energy to use

without requiring mechanical devices to without requiring mechanical devices to distribute the collected heat distribute the collected heat

o Certain design features can enhance Certain design features can enhance passive solar energy’s heating potentialpassive solar energy’s heating potential• South facing windows (in N. hemisphere)South facing windows (in N. hemisphere)• Well insulated buildingsWell insulated buildings• Attic ventsAttic vents• Overhangs and solar sunspacesOverhangs and solar sunspaces

Solar Solar sunspacesunspace

o Utilizes passive Utilizes passive solar energy to solar energy to heat and cool heat and cool homeshomes

o Can be added to Can be added to existing homesexisting homes

Heating Buildings and WaterHeating Buildings and Watero Active Solar EnergyActive Solar Energy

• System of collecting and absorbing the System of collecting and absorbing the sun’s energy, and using pumps or fans sun’s energy, and using pumps or fans distribute the collected heat distribute the collected heat

o Most commonMost common• Series of collection Series of collection

devices on roofs or devices on roofs or in fieldsin fields

• Typically a black Typically a black panel or platepanel or plate

o Used to heat waterUsed to heat water

Heating Buildings and WaterHeating Buildings and Water

o Solar Thermal Electric GenerationSolar Thermal Electric Generation• Means of producing electricity in which the Means of producing electricity in which the

sun’s energy is concentrated by mirrors or sun’s energy is concentrated by mirrors or lenses to either heat a fluid filled pipe or lenses to either heat a fluid filled pipe or drive a Stirling engine drive a Stirling engine

o More efficient than other solar More efficient than other solar technologiestechnologies

o BenefitsBenefits• No air pollutionNo air pollution• No contribution to global warming or acid No contribution to global warming or acid

precipitationprecipitation

Solar Thermal Electric Solar Thermal Electric GenerationGeneration

Photovoltaic Solar CellsPhotovoltaic Solar Cells

o Thin cells are treated with certain Thin cells are treated with certain metals so that they generate electricity metals so that they generate electricity when they absorb solar energy when they absorb solar energy

o Convert sunlight Convert sunlight directly into energydirectly into energy

o No pollution and No pollution and minimal maintenanceminimal maintenance

o Used on any scaleUsed on any scale• Lighted road signsLighted road signs• Entire buildings Entire buildings

Photovoltaic Solar CellsPhotovoltaic Solar Cellso Can be incorporated into building materialsCan be incorporated into building materials

• Roofing shinglesRoofing shingles• TileTile• Window glassWindow glass

Cost of Electrical Power PlantsCost of Electrical Power Plants

Indirect Solar EnergyIndirect Solar Energyo BiomassBiomass

• Plant materials used as fuelPlant materials used as fuel• Ex: wood, crop wastes, sawdust, and animal wastes Ex: wood, crop wastes, sawdust, and animal wastes

• Contains energy from sun via Contains energy from sun via photosynthesizing plantsphotosynthesizing plants

• Renewable when used no Renewable when used no faster than it can be faster than it can be producedproduced

o Can convert to biogas or Can convert to biogas or liquidsliquids• Ethanol and methanolEthanol and methanol

Advantages and Disadvantages of Advantages and Disadvantages of BiomassBiomass

o AdvantagesAdvantages• Reduces dependence on fossil fuelsReduces dependence on fossil fuels• Often uses waste materialsOften uses waste materials• If trees are planted at same rate biomass is If trees are planted at same rate biomass is

combusted, no net increase in atmospheric combusted, no net increase in atmospheric COCO22

o DisadvantagesDisadvantages• Requires land, water and energyRequires land, water and energy• Can lead to Can lead to

• DeforestationDeforestation• DesertificationDesertification• Soil erosionSoil erosion

Indirect Solar Indirect Solar EnergyEnergy

o Wind EnergyWind Energy• Electric or mechanical Electric or mechanical

energy obtained from energy obtained from surface air currents caused surface air currents caused by solar warming of air by solar warming of air

• World’s fastest growing World’s fastest growing source of energysource of energy

o Wind results from sun Wind results from sun warming the atmospherewarming the atmosphere• Varies in direction and Varies in direction and

magnitudemagnitude

o New wind turbines New wind turbines harness wind efficientlyharness wind efficiently

Wind EnergyWind Energy

• Kills birds and Kills birds and batsbats

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

o Biggest Biggest constraintsconstraints• Cost Cost • Public resistancePublic resistance

o Most profitable in rural areas with Most profitable in rural areas with constant windconstant wind

o Few environmental problemsFew environmental problems

Indirect Solar Indirect Solar EnergyEnergy

o HydropowerHydropower• Form of renewable Form of renewable

energy reliant on energy reliant on flowing or falling flowing or falling water to generate water to generate mechanical energy or mechanical energy or electricity electricity

o Sun’s energy drive Sun’s energy drive hydrologic cyclehydrologic cycle

o Most efficient energy Most efficient energy source (90%)source (90%)

HydropowerHydropower

o Generates 19% of world’s energyGenerates 19% of world’s energyo Traditional hydropower Traditional hydropower

• Only suited for large damsOnly suited for large damso New technologyNew technology

• May be able to utilize low flow waterwaysMay be able to utilize low flow waterwayso Problems with DamsProblems with Dams

• Changes natural flow of riversChanges natural flow of rivers• Disrupts migratory fish patternsDisrupts migratory fish patterns• Potential dam breaksPotential dam breaks

Other Indirect Solar EnergyOther Indirect Solar Energy

o Ocean wavesOcean waves• Produced by windsProduced by winds• Has potential to turn a turbine- and create Has potential to turn a turbine- and create

electricityelectricity

o Ocean Temperature GradientsOcean Temperature Gradients• Use difference in temperature of surface Use difference in temperature of surface

and deep water to create electricityand deep water to create electricity

Other Renewable Other Renewable Energy SourcesEnergy Sources

o Geothermal EnergyGeothermal Energy• Energy from the Energy from the

Earth’s interior for Earth’s interior for either space heating either space heating or generation of or generation of electricity electricity

o From Hydrothermal From Hydrothermal Reservoirs (left)Reservoirs (left)• Created by Created by

volcanoesvolcanoes• Reservoirs used Reservoirs used

directly for heat or directly for heat or to generate to generate electricityelectricity

Geothermal EnergyGeothermal Energy

o From hot, dry rockFrom hot, dry rocko Geothermal heat Geothermal heat

pumpspumps• Use difference in Use difference in

temperature temperature between surface and between surface and subsurfacesubsurface

• Great for heating Great for heating buildingsbuildings

• Expensive Expensive installationinstallation

Other Renewable Energy Other Renewable Energy SourcesSources

o Tidal EnergyTidal Energy• Form of renewable energy that relies of the Form of renewable energy that relies of the

ebb and flow of the tides to generate ebb and flow of the tides to generate electricity electricity

o Typical difference between high and Typical difference between high and low tide is 1-2 ftlow tide is 1-2 ft• Narrow bays may have greater variationNarrow bays may have greater variation

o Energy can be captured with Energy can be captured with • A dam across the bayA dam across the bay• A turbine similar to a wind turbineA turbine similar to a wind turbine

Hydrogen as a Fuel SourceHydrogen as a Fuel Source

o Advantages to Hydrogen as a fuel sourceAdvantages to Hydrogen as a fuel source• Very high energy densityVery high energy density• Can be produced from any electrical sourceCan be produced from any electrical source

• Electrolysis (see illustration on next slide)Electrolysis (see illustration on next slide)• No greenhouse gases and few other No greenhouse gases and few other

pollutantspollutants• Can be used in vehiclesCan be used in vehicles

o Disadvantages to Hydrogen as a fuel Disadvantages to Hydrogen as a fuel sourcesource• Highly volatile (requires special storage)Highly volatile (requires special storage)• Relatively inefficientRelatively inefficient

Hydrogen as a Fuel Source-Hydrogen as a Fuel Source-ElectrolysisElectrolysis

Hydrogen Fuel CellHydrogen Fuel Cell

o Fuel cellFuel cell• Device that directly converts chemical energy Device that directly converts chemical energy

into electricity into electricity • Requires hydrogen Requires hydrogen

from a tank and from a tank and oxygen from the air oxygen from the air

o Similar to a Similar to a battery, only the battery, only the reactants are reactants are supplied from supplied from outside sourceoutside source

Future Applications of Fuel CellsFuture Applications of Fuel Cells

o VehiclesVehicles• Not yet commonly Not yet commonly

availableavailable• Hydrogen is not Hydrogen is not

yet readily yet readily available as a fuel available as a fuel sourcesource

o Batteries in cell Batteries in cell phones or laptopsphones or laptops

Energy Consumption Trends and Energy Consumption Trends and EconomicsEconomics

Energy Efficient TechnologiesEnergy Efficient Technologies

o Super-insulated Super-insulated buildings (right)buildings (right)

o Energy efficient Energy efficient appliancesappliances

o AutomobilesAutomobileso Aircraft technologyAircraft technology

o Compact Fluorescent light bulbsCompact Fluorescent light bulbso Condensing furnacesCondensing furnaces

CogenerationCogeneration

o Production of two useful forms of Production of two useful forms of energy from the same fuel energy from the same fuel

Energy Savings in Commercial Energy Savings in Commercial BuildingsBuildings

Saving Energy at HomeSaving Energy at Home