Chapter 13Chapter 13Renewable Energy and Renewable Energy and ConservationConservation

Overview of Chapter 13Overview of Chapter 13

Direct Solar EnergyDirect Solar Energy Indirect Solar EnergyIndirect Solar Energy

WindWind BiomassBiomass HydropowerHydropower GeothermalGeothermal TidalTidal

High and Low Technology Energy High and Low Technology Energy SolutionSolution

Direct Solar EnergyDirect Solar Energy Perpetually availablePerpetually available 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

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

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 Utilizes passive Utilizes passive

solar energy to solar energy to heat and cool heat and cool homeshomes

Can be added Can be added to existing to existing homeshomes

Typically used to Typically used to heat waterheat water 8% of energy in 8% of energy in

US is used to US is used to heat waterheat water

This technology This technology could supply could supply large amount of large amount of US energy US energy demanddemand

Heating Buildings and WaterHeating Buildings and Water 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

Heating Buildings and WaterHeating Buildings and Water

Solar Thermal Electric GenerationSolar Thermal Electric Generation Means of producing electricity in which Means of producing electricity in which

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

More efficient than other solar More efficient than other solar technologiestechnologies No air pollutionNo air pollution No contribution to global warming or No contribution to global warming or

acid precipitationacid precipitation

Solar Thermal Electric Solar Thermal Electric GenerationGeneration

Photovoltaic Solar CellsPhotovoltaic Solar Cells A wafer or thin film that is treated A wafer or thin film that is treated

with certain metals so that they with certain metals so that they generate electricity when they generate electricity when they absorb solar energy absorb solar energy No pollution and No pollution and

minimal minimal maintenancemaintenance

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

Photovoltaic Solar CellsPhotovoltaic Solar Cells

Can be Can be incorporated incorporated into building into building materialsmaterials Roofing Roofing

shinglesshingles TileTile Window Window

glassglass

More economical than running More economical than running electrical lines to rural areaselectrical lines to rural areas

Cost of Electrical Power Cost of Electrical Power PlantsPlants Alternative Alternative

power power sources are sources are becoming becoming competitive competitive with with traditional traditional power power sourcessources

Indirect Solar EnergyIndirect Solar Energy

BiomassBiomass Plant materials, such as wood, crop Plant materials, such as wood, crop

wastes and animal waste, used as fuelwastes and animal waste, used as fuel Wind energyWind energy

Electric or mechanical energy obtained Electric or mechanical energy obtained from surface air currents caused by from surface air currents caused by solar warming of airsolar warming of air

HydropowerHydropower Form of renewable energy reliant on Form of renewable energy reliant on

flowing or falling water to generate flowing or falling water to generate mechanical energy or electricitymechanical energy or electricity

BiomassBiomass

Contains energy from sun via photo-Contains energy from sun via photo-synthesizing plantssynthesizing plants Oldest known fuel to humans - still used by half Oldest known fuel to humans - still used by half

the world’s populationthe world’s population Renewable when used no faster than it can be Renewable when used no faster than it can be

producedproduced

Can convert to Can convert to biogas or liquidsbiogas or liquids Ethanol and Ethanol and

methanolmethanol Clean fuelClean fuel

BiomassBiomass

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

DisadvantagesDisadvantages Requires land, water and fossil fuel energyRequires land, water and fossil fuel energy Can lead to Can lead to

DeforestationDeforestation DesertificationDesertification Soil erosionSoil erosion

Wind EnergyWind Energy World’s fastest growing World’s fastest growing

source of energysource of energy Wind results from sun Wind results from sun

warming the warming the atmosphereatmosphere Varies in direction and Varies in direction and

magnitudemagnitude New wind turbines New wind turbines

harness wind efficientlyharness wind efficiently Most profitable in rural Most profitable in rural

areas with constant windareas with constant wind

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

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

Most widely used form Most widely used form of solar energyof solar energy 19% of world’s energy19% of world’s energy

Traditional Traditional hydropowerhydropower Suited only to large Suited only to large

damsdams New technologyNew technology

Utilize low flow systemsUtilize low flow systems

HydropowerHydropower

Other Indirect Solar EnergyOther Indirect Solar Energy

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

create electricitycreate electricity 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 Energy Other Renewable Energy SourcesSources Geothermal energyGeothermal energy

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

Tidal EnergyTidal Energy Form of renewable energy that relies of Form of renewable energy that relies of

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

Enormous energy sourceEnormous energy source 1% of heat in upper 10 km of earth crust 1% of heat in upper 10 km of earth crust

is equal to 500x the earth’s fossil fuel is equal to 500x the earth’s fossil fuel sourcessources

Geothermal EnergyGeothermal Energy

From From Hydrothermal Hydrothermal ReservoirsReservoirs 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

From hot, dry rockFrom hot, dry rock Geothermal heat Geothermal heat

pumpspumps Use difference in Use difference in

temperature temperature between surface between surface and subsurfaceand subsurface

Great for heating Great for heating buildingsbuildings

Expensive Expensive installationinstallation

Tidal EnergyTidal Energy

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

Potential energy difference between Potential energy difference between low and high tide can be captured low and high tide can be captured with with A dam across a bayA dam across a bay A turbine similar to a wind turbineA turbine similar to a wind turbine

High and Low Technology High and Low Technology Energy SolutionsEnergy Solutions

Most promising “energy sources” are Most promising “energy sources” are energy conservation and energy energy conservation and energy efficiencyefficiency

Energy ConservationEnergy Conservation Using less energy by reducing energy Using less energy by reducing energy

use and wasteuse and waste Energy EfficiencyEnergy Efficiency

Using less energy to accomplish a given Using less energy to accomplish a given tasktask

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

Hydrogen as a Fuel SourceHydrogen as a Fuel Source

AdvantagesAdvantages Very high energy densityVery high energy density Can be produced from any electrical Can be produced from any electrical

sourcesource 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 use in vehiclesCan be use in vehicles Disadvantages Disadvantages

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

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

into electricity into electricity Requires Requires

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

Similar to a Similar to a battery, but battery, but reactants are reactants are supplied from supplied from outside sourceoutside source

Future Applications of Fuel Future Applications of Fuel CellsCells Hydrogen Fuel Hydrogen Fuel

Cell VehiclesCell Vehicles Hydrogen is not Hydrogen is not

yet readily yet readily available as a fuel available as a fuel sourcesource 61 hydrogen 61 hydrogen

fueling stations in fueling stations in USUS

Batteries in cells Batteries in cells phones or laptopsphones or laptops

Energy Consumption Trends Energy Consumption Trends and Economicsand Economics

Super-insulated buildings (right)Super-insulated buildings (right) Energy efficient appliancesEnergy efficient appliances AutomobilesAutomobiles Aircraft technologyAircraft technology Compact FluorescentCompact Fluorescent

light bulbslight bulbs Condensing furnacesCondensing furnaces

Energy Efficient Energy Efficient TechnologiesTechnologies

CogenerationCogeneration

Production of two useful forms of Production of two useful forms of energy from the same fuelenergy from the same fuel Most effective on small scale Most effective on small scale

Energy Savings in Energy Savings in Commercial BuildingsCommercial Buildings

Saving Energy at HomeSaving Energy at Home