Chapter 16: Alternative Energy and the Environment.

Chapter 16:Chapter 16:Alternative Energy and the Alternative Energy and the EnvironmentEnvironment

OverviewOverview Introduction to Alternative Energy Introduction to Alternative Energy

SourcesSources Solar EnergySolar Energy Converting Electricity from Renewable Converting Electricity from Renewable

Energy into a Fuel for VehiclesEnergy into a Fuel for Vehicles Water PowerWater Power Ocean EnergyOcean Energy Wind PowerWind Power BiofuelsBiofuels Geothermal EnergyGeothermal Energy

Introduction to Alternative Introduction to Alternative Energy SourcesEnergy Sources

Nonrenewable alternative energyNonrenewable alternative energy Nuclear Nuclear

Requires a mineral fuel mined from EarthRequires a mineral fuel mined from Earth Geothermal Geothermal

Heat is extracted faster than it is Heat is extracted faster than it is replenishedreplenished

Renewable energy sourcesRenewable energy sources Solar, fresh water, wind, ocean, and Solar, fresh water, wind, ocean, and

biofuelsbiofuels All derive from the sun’s energyAll derive from the sun’s energy

Solar EnergySolar Energy

10 weeks of 10 weeks of solar energy solar energy equivalent to all equivalent to all known fossil known fossil fuel reservesfuel reserves

Two typesTwo types PassivePassive ActiveActive

Passive Solar EnergyPassive Solar Energy

Promotes cooling in hot weather and Promotes cooling in hot weather and retaining heat in cold weatherretaining heat in cold weather

Methods include:Methods include: Overhangs that block summer sun but Overhangs that block summer sun but

allow winter sun allow winter sun Walls in buildings that absorbs heat Walls in buildings that absorbs heat

during the day and releases it at nightduring the day and releases it at night Deciduous trees as landscapingDeciduous trees as landscaping

Active SolarActive Solar

Energy systems that require Energy systems that require mechanical powermechanical power Electric pump circulate air, water or Electric pump circulate air, water or

other fluids from solar collectors to a other fluids from solar collectors to a location where heat is storedlocation where heat is stored

Additional pumps move heat to location Additional pumps move heat to location where energy is converted and usedwhere energy is converted and used

Solar CollectorsSolar Collectors Provide space Provide space

heating or hot waterheating or hot water Flat Plate CollectorFlat Plate Collector

Flat, glass-covered Flat, glass-covered plates over a black plates over a black background where background where absorbing fluid is absorbing fluid is circulated through circulated through tubestubes

Evacuated tube Evacuated tube collectorcollector

Each tube filled with Each tube filled with absorbing fluid pass absorbing fluid pass through a larger tubethrough a larger tube

PhotovoltaicPhotovoltaic

Converts sunlight directly into Converts sunlight directly into electricityelectricity Made from thin layers of Made from thin layers of

semiconductors and a solid-state semiconductors and a solid-state electronic components with few or no electronic components with few or no moving partsmoving parts

World’s faster growing source of World’s faster growing source of energyenergy

PhotovoltaicPhotovoltaic

Don’t have Don’t have ability to build a ability to build a electrical gridelectrical grid

Systems can Systems can power lights and power lights and televisions in televisions in small villagessmall villages

Off the grid Off the grid Emerging as a major contributor to Emerging as a major contributor to

developing countriesdeveloping countries

Solar Thermal GeneratorsSolar Thermal Generators Focus sunlight onto Focus sunlight onto

water-holding water-holding containers containers Traditionally built Traditionally built

using solar power using solar power towerstowers

Water boils and is Water boils and is used to run used to run conventional steam-conventional steam-driven electrical driven electrical generatorsgenerators

Built with very large Built with very large output output

Solar Thermal GeneratorsSolar Thermal Generators

In newer facilityIn newer facility Mirrors focus solar energy onto pipes Mirrors focus solar energy onto pipes

with heat-absorbing fluidwith heat-absorbing fluid

Solar Energy and the Solar Energy and the EnvironmentEnvironment

Generally low impactGenerally low impact One concernOne concern

Variety of metals, glass plastics, and Variety of metals, glass plastics, and fluids used in the manufacture and use fluids used in the manufacture and use of solar equipmentof solar equipment

Production and accidental spills could Production and accidental spills could release toxic materialsrelease toxic materials

Converting Electricity from Converting Electricity from Renewable Energy to a Fuel that Renewable Energy to a Fuel that can be Burned and can Power can be Burned and can Power VehiclesVehicles Two choices:Two choices:

Store electricity in batteries and use Store electricity in batteries and use electric vehicleselectric vehicles

Transfer the energy in the electricity to Transfer the energy in the electricity to a gaseous or liquid fuela gaseous or liquid fuel

HydrogenHydrogen

Hydrogen FuelHydrogen Fuel

Hydrogen as power for fuel cellsHydrogen as power for fuel cells Electric current separates water into Electric current separates water into

hydrogen and oxygenhydrogen and oxygen When H recombined with O, electrons When H recombined with O, electrons

flow between positive and negative flow between positive and negative polespoles

An electric currentAn electric current H Can be transported in pipelineH Can be transported in pipeline

Combustion product is waterCombustion product is water Clean fuelClean fuel

Water PowerWater Power

A form of stored solar energyA form of stored solar energy Long historyLong history Waterwheels convert water power to Waterwheels convert water power to

mechanical energymechanical energy Today’s hydroelectric power plants Today’s hydroelectric power plants

use water stored behind damsuse water stored behind dams Also produced through the process of Also produced through the process of

pump storagepump storage

Small-Scale SystemsSmall-Scale Systems

Electrical power produced by large Electrical power produced by large dams will not increase dams will not increase Most dam sites already utilizedMost dam sites already utilized Small scale systems have potential in Small scale systems have potential in

mountainous areas along streamsmountainous areas along streams

Water Power and the Water Power and the EnvironmentEnvironment AdvantagesAdvantages

Water power is clean and efficient Water power is clean and efficient powerpower

No burning of fuel, no radioactive wasteNo burning of fuel, no radioactive waste DisadvantagesDisadvantages

Flood large tracts of landFlood large tracts of land Block fish migrationBlock fish migration Trap sediment that would replenish Trap sediment that would replenish

beachesbeaches Evaporative loss of water from Evaporative loss of water from

reservoirsreservoirs

Ocean EnergyOcean Energy

High energy in High energy in motion of waves, motion of waves, currents and tides currents and tides in the oceanin the ocean Difficult to harnessDifficult to harness

Storms destructive Storms destructive and water corrosiveand water corrosive

Most successful = Most successful = tidal powertidal power

Very few areas w/ Very few areas w/ the right topographythe right topography

Tidal PowerTidal Power

Dam built across the entrance to a Dam built across the entrance to a bay or estuarybay or estuary Water held in or out of bay until Water held in or out of bay until

significant difference in level forces significant difference in level forces water in or outwater in or out

This runs the turbinesThis runs the turbines Environmental impactsEnvironmental impacts

Changes hydrology of bayChanges hydrology of bay Restricts passage of fishRestricts passage of fish Changes habitat for birds and other Changes habitat for birds and other

organismsorganisms

Wind PowerWind Power

Wind produced when differential Wind produced when differential heating of Earth’s surface create air heating of Earth’s surface create air masses with differing heat contents masses with differing heat contents and densitiesand densities

Wind energy is the cheapest form of Wind energy is the cheapest form of alternative energyalternative energy Less than natural gas and coalLess than natural gas and coal Now used in many place including Now used in many place including

offshoreoffshore

Wind PowerWind Power

Problems Problems Wind highly Wind highly

variable in time, variable in time, place, and place, and intensityintensity

Wind velocity Wind velocity often increases often increases over hill tops or over hill tops or funneled through funneled through a mountain passa mountain pass

Wind Power and the Wind Power and the EnvironmentEnvironment Wind energy Wind energy

does have a does have a few few disadvantagesdisadvantages Kills birdsKills birds Use large areas Use large areas

of landof land May degrade May degrade

area’s scenic area’s scenic resourcesresources

Future of Wind PowerFuture of Wind Power

Growing at approximately 30% per Growing at approximately 30% per yearyear Nearly 10 times the growth rate of oil Nearly 10 times the growth rate of oil

useuse Created thousands of jobs and Created thousands of jobs and

investment opportunitiesinvestment opportunities Technology producing more efficient Technology producing more efficient

wind turbineswind turbines

Biofuels and Human HistoryBiofuels and Human History

Energy from biomass is the oldest Energy from biomass is the oldest fuel used by humans.fuel used by humans. Until end of 19Until end of 19thth century major fuel century major fuel

source in the USsource in the US 1 billion people in the world still use 1 billion people in the world still use

wood as primary source of energy for wood as primary source of energy for heat and cookingheat and cooking

Includes: firewood, cattle dung, peat Includes: firewood, cattle dung, peat

BiofuelsBiofuels

Energy recovered from biomass-Energy recovered from biomass-organic matterorganic matter

Three groupsThree groups FirewoodFirewood Organic wastesOrganic wastes Crops grown to be converted into liquid Crops grown to be converted into liquid

fuelsfuels

Biofuels and the Biofuels and the EnvironmentEnvironment Can pollute the air and degrade the Can pollute the air and degrade the

landland World’s forests will decrease if our need World’s forests will decrease if our need

for forest products and forest biomass for forest products and forest biomass fuel exceeds the productivity of the fuel exceeds the productivity of the forestsforests

Combustion of biomass-derived fuel Combustion of biomass-derived fuel generally release fewer pollutants then generally release fewer pollutants then combustion of coal/gasolinecombustion of coal/gasoline

But burning urban waste can release heavy But burning urban waste can release heavy metalsmetals

Geothermal EnergyGeothermal Energy

Deep earth - high densityDeep earth - high density Energy from interior of earthEnergy from interior of earth Mined and used to heat buildings and generate Mined and used to heat buildings and generate

electricityelectricity May be considered nonrenewable when rates May be considered nonrenewable when rates

of extraction are greater than rates of natural of extraction are greater than rates of natural replenishmentreplenishment

Shallow earth - low densityShallow earth - low density Solar energy that has traveled to shallow Solar energy that has traveled to shallow

depthsdepths

Geothermal SystemsGeothermal Systems

Areas of high heat flow occur at plate Areas of high heat flow occur at plate boundariesboundaries Divergent and convergent plate Divergent and convergent plate

boundariesboundaries Hydrothermal convection- transfers Hydrothermal convection- transfers

heat from depths to surfaceheat from depths to surface Using steam or hot waterUsing steam or hot water

GeothermalGeothermal

Most groundwater can be considered Most groundwater can be considered a source of geothermal energya source of geothermal energy Groundwater at a depth of 100m is 13Groundwater at a depth of 100m is 13ooC C

or 55or 55ooFF In summer heat can be transferred to In summer heat can be transferred to

the cool waterthe cool water In winter heat can be transferred from In winter heat can be transferred from

the water to the airthe water to the air

Geothermal Energy and the Geothermal Energy and the EnvironmentEnvironment

Problems:Problems: Considerable thermal pollution from hot Considerable thermal pollution from hot

wastewaterswastewaters Water may be saline or highly corrosiveWater may be saline or highly corrosive On-site noiseOn-site noise Emissions of gasEmissions of gas Disturbance of landDisturbance of land

Future of Geothermal Future of Geothermal EnergyEnergy GeothermalGeothermal

Could produce 10% of the electricity Could produce 10% of the electricity needed for the western USneeded for the western US

Geohydrothermal Geohydrothermal Could potentially provide four times that Could potentially provide four times that

(10% of US total)(10% of US total)