Environmental Environmental ScienceScience

Chapter 18: Renewable Chapter 18: Renewable EnergyEnergy

Chapter 18 TargetsChapter 18 Targets I can listI can list six forms of six forms of renewablerenewable energy, and compare energy, and compare

their advantages and disadvantages.their advantages and disadvantages.

I can describeI can describe the difference between the difference between passivepassive solar solar heating, heating, activeactive solar heating, and solar heating, and photovoltaicphotovoltaic energy.energy.

I can describeI can describe the current state of the current state of windwind energy energy technology.technology.

I can explainI can explain the differences in biomass fuel use the differences in biomass fuel use between developbetween developeded and develop and developing ing nations.nations.

I can describeI can describe how how hydroelectrichydroelectric energy, geothermal energy, geothermal energyenergy, and geothermal , and geothermal heatheat pumps work. pumps work.

Renewable EnergyRenewable Energy Renewable energyRenewable energy:: energy from energy from

sources that are sources that are constantly being constantly being formed formed

Types of renewable energy:Types of renewable energy:• SolarSolar energy (3 Ways) energy (3 Ways)• WindWind energy energy• KineticKinetic energy of moving energy of moving water water (3 Ways)(3 Ways)• Earth’s Earth’s heat heat

Solar Energy can be usedSolar Energy can be used3 ways:3 ways:

1.1. Solar HeatingSolar Heating

2.2. Solar Heating Solar Heating Electricity Electricity

3.3. Solar Energy Solar Energy Electricity Electricity

Solar Hot Water Solar Hot Water 1890: 1890: solar water heaters solar water heaters used in sunny states used in sunny states

like California, Arizona, and Floridalike California, Arizona, and Florida

1920: 1,000’s of solar water heaters had been sold. 1920: 1,000’s of solar water heaters had been sold. • BUT … large deposits of oil and natural gas were BUT … large deposits of oil and natural gas were

discovered in western United States. These low discovered in western United States. These low cost fuels became available, solar water systems cost fuels became available, solar water systems were replaced with heaters were replaced with heaters burning fossil fuelsburning fossil fuels. .

Solar collector forheating water

A home in California in 1906

• Today, Today, solar water heaters solar water heaters making a comeback (more than making a comeback (more than half a million in California alone!)half a million in California alone!)

• Heat water for Heat water for useuse inside inside homes/businesses and swimming homes/businesses and swimming pools (see picture) pools (see picture)

• Panels on building’s roof contain Panels on building’s roof contain water pipes. Sun hits panels and water pipes. Sun hits panels and pipes. pipes.

• Warmed water Warmed water then used in a then used in a swimming poolswimming pool

Passive Passive vs. vs. ActiveActive Solar Solar HeatingHeating

Active Solar Heating System Video

Solar Thermal Electricity Solar Thermal Electricity Solar energy Solar energy electricity electricity

Some solar power plants Some solar power plants (see picture from California's Mojave (see picture from California's Mojave

Desert)Desert) use curved mirrors use curved mirrors called called parabolic troughs parabolic troughs to to focus sunlight on a pipe focus sunlight on a pipe running down center of mirror.running down center of mirror.

Mirror focuses sunlight on Mirror focuses sunlight on pipe, causing water inside to pipe, causing water inside to boilboil and produce steam. and produce steam. Steam is then used to turn a Steam is then used to turn a turbineturbine to make to make electricityelectricity. .

SOLAR THERMAL ELECTRICITYSOLAR THERMAL ELECTRICITY

Solar Thermal Electricity Solar Thermal Electricity PROBLEM: Works only when sun is PROBLEM: Works only when sun is shiningshining. .

On cloudy days/at night, power plants can't On cloudy days/at night, power plants can't create energy. create energy.

Some solar plants, use "Some solar plants, use "hybridhybrid" " technologytechnology During day they use sun. At During day they use sun. At night/cloudy days they burn night/cloudy days they burn natural gas natural gas to to boil the water to generate electricity.boil the water to generate electricity.

Another form of solar power (heat) to make electricity: (Central Tower Power Plant)

Sunlight is reflected off 1,800 mirrors (heliostats) circling the tall tower.

A fluid (liquid sodium) is heated by the sun's rays. That fluid is used to boil water to make steam to turn a turbine and a generator.

This experimental power plant is called Solar II and was built in the Mojave desert.

Solar Cells or Photovoltaic Solar Cells or Photovoltaic Energy Energy Sunlight converted directly to electricity

using solar cells Solar cells also called photovoltaic cells

(PV cells); can be found on many small appliances, like calculators, and even on spacecraft

First developed in 1950’s for U.S. space satellites; made of silicon, a special type of melted sand

Sunlight strikes solar cells and electrons are knocked loose. They move toward treated front surface. When the two surfaces are joined by a wire, a current of electricity occurs between the negative and positive sides.

Solar cells PV module Array Some arrays are set on special tracking

devices to follow sunlight all day long.

Solar energy is stored in batteries to light roadside billboards at night or for emergency roadside cell phones when no telephone wires are around

Some experimental cars also use PV cells - convert sunlight directly into electricity to power motors on the car

Solar cells are used in satellites in outer space - see the picture of solar panels extending out from a satellite

Biomass EnergyBiomass Energy BiomassBiomass = waste from = waste from

organisms organisms

• Dead trees, branches, Dead trees, branches, yard clippings, left-over yard clippings, left-over crops, wood chips, bark crops, wood chips, bark and sawdust from and sawdust from lumber mills (even lumber mills (even manure)manure)

Trash that can't be Trash that can't be recycled recycled landfilllandfill

Using biomass for Using biomass for fuelfuel cuts down need for cuts down need for "landfills" to hold garbage "landfills" to hold garbage

Energy from Biomass Video

Biomass to ElectricityBiomass to Electricity 60 million tons of biomass 60 million tons of biomass

(amount produced by most (amount produced by most states) states) 2,000 megawatts of 2,000 megawatts of electricity electricity (enough for (enough for 2 million 2 million homes!) homes!)

How biomass worksHow biomass works: :

1.1. Biomass gathered in big Biomass gathered in big truckstrucks

2.2. Waste taken to biomass Waste taken to biomass powerpower plant plant

3.3. Biomass fed into furnace and Biomass fed into furnace and burnedburned

4.4. Heat used to Heat used to boilboil water, and water, and steam turns steam turns turbinesturbines and and generatorsgenerators

Landfill GasLandfill Gas Biomass can also be “Biomass can also be “tappedtapped” at landfills ” at landfills

(LANDFILL GAS)(LANDFILL GAS)1. Garbage decomposes 1. Garbage decomposes methane methane

gas gas 2. Pipelines collect methane gas that is 2. Pipelines collect methane gas that is

used in power plants to make electricityused in power plants to make electricity

Similar thing can be done at animal feed Similar thing can be done at animal feed lots / places where many animals are raised. lots / places where many animals are raised. When manure decomposes When manure decomposes methane gas methane gas burned at burned at the farm to make energy the farm to make energy to run the farmto run the farm. .

Landfill Gas to Electricity Video

The Future of BiomassThe Future of Biomass Biomass is Biomass is renewablerenewable

because plants can be because plants can be grown over and overgrown over and over

Another use of biomass is Another use of biomass is ethanolethanol, a liquid alcohol , a liquid alcohol fuelfuel• Ethanol is used in Ethanol is used in

special cars designed to special cars designed to use alcohol fuel instead use alcohol fuel instead of gasolineof gasoline

• The alcohol can also be The alcohol can also be combined with gasoline combined with gasoline (gasohol) and reduce (gasohol) and reduce our dependence on oilour dependence on oil

Geothermal Energy Geothermal Energy ""Geo" = earth "thermal" = heatGeo" = earth "thermal" = heat

Below earth’s crust, top layer of mantle Below earth’s crust, top layer of mantle is hot liquid rock called magma.is hot liquid rock called magma.

For every 328 feet below ground, For every 328 feet below ground, temperature increases 5.4temperature increases 5.4ooF. At 10,000 F. At 10,000 feet below ground, the temperature is feet below ground, the temperature is hot enough to hot enough to boil waterboil water. .

Deeper under the surface, hot water Deeper under the surface, hot water can reach temperatures more than can reach temperatures more than 300300ooF (hotter than boiling water F (hotter than boiling water 212212ooF). It doesn't turn to steam F). It doesn't turn to steam because it is not in contact with because it is not in contact with the airthe air. .

Geysers? (Old Faithful pictured at right)Geysers? (Old Faithful pictured at right)

Geothermal Today Geothermal Today In U.S., we In U.S., we geothermallygeothermally

heat water in swimming heat water in swimming pools and health spas pools and health spas

Hot water from Hot water from below below ground ground can be used to can be used to heat buildings during heat buildings during winter. The hot water runs winter. The hot water runs through insulated pipes to through insulated pipes to public buildings. public buildings.

IcelandIceland has at least 25 has at least 25 active volcanoes and active volcanoes and many hot springs and many hot springs and geysers, this country uses geysers, this country uses the most geothermal the most geothermal energy globallyenergy globally

Geothermal Energy in Iceland Video

Geothermal Electricity Geothermal Electricity Steam from Steam from belowbelow ground ground

electricity in geothermal power electricity in geothermal power plantplant

1.1.Holes Holes drilleddrilled into ground and into ground and pipes lowered into pipes lowered into steamsteam

2.2.Steam comes up through Steam comes up through pipes pipes

3.3.Steam causes Steam causes turbineturbine blades to blades to spin and a generator to make spin and a generator to make electricityelectricity

4.4.Steam is cooled off in Steam is cooled off in cooling cooling towertower and pumped and pumped back below back below ground to be ground to be reheated by the reheated by the earth earth

HydroelectricityHydroelectricity Hydroelectric power kinetic energy of moving

water electricity

Dams built across large rivers

Hydro power today is found in mountainous areas of states where there are lakes and reservoirs and along rivers

Washington state leads nation in hydroelectricity 87% is produced by hydroelectric facilities

Hydroelectricity Video

How a Hydro Dam Works How a Hydro Dam Works 1.1. Water behind dam flows Water behind dam flows

through intake into pipe through intake into pipe called a called a penstock penstock

2.2. Water pushes against Water pushes against blades in a blades in a turbine turbine

3.3. Turbine spins a Turbine spins a generatorgenerator to produce to produce electricityelectricity. The . The electricity travels via electricity travels via electric lines to homes, electric lines to homes, schools, factories and schools, factories and businessesbusinesses

Ocean Energy Ocean Energy

3 basic ways to tap ocean for energy:3 basic ways to tap ocean for energy:

1.1.Waves Waves

2.2.High and low High and low tidestides

3.3.TemperatureTemperature differences in the water differences in the water

Wave Energy Wave Energy Moving waves Moving waves KineticKinetic energy energy

Wave turbine:Wave turbine:1.1. Wave Wave risesrises into a chamber. into a chamber. 2.2. Rising water forces Rising water forces air out air out of chamber. of chamber. 3.3. Moving air spins a Moving air spins a turbineturbine which turns a which turns a

generator. generator. 4.4. When the wave goes down, air flows through When the wave goes down, air flows through

the turbine and back into the chamber the turbine and back into the chamber through doors that are normally closed. through doors that are normally closed.

Most wave-energy systems are very Most wave-energy systems are very smallsmall. . They can be used to power a warning buoy or a They can be used to power a warning buoy or a small light house. small light house.

Wave Energy Animation

Tidal Energy Tidal Energy An increase of at least An increase of at least 16 16

feet feet between low tide to between low tide to high tide is needed for high tide is needed for tidal electricity to be tidal electricity to be generated directly. generated directly.

When tides come into When tides come into shore, they may be shore, they may be trappedtrapped in reservoirs in reservoirs behind dams. When the behind dams. When the tide drops, water behind tide drops, water behind the dam can be let out the dam can be let out just like a just like a hydroelectrichydroelectric power plant. power plant.

Tidal Power Video

Ocean Thermal Energy Ocean Thermal Energy Conversion (OTEC) Conversion (OTEC)

Uses Uses temperaturetemperature differences in the ocean. differences in the ocean. SunSun warms surface water more than deep ocean water. warms surface water more than deep ocean water. OTEC plant produces energy using the following steps:OTEC plant produces energy using the following steps:

• Warm surface water is Warm surface water is boiledboiled in a vacuum chamber. in a vacuum chamber.• This produces a steam that drives a This produces a steam that drives a turbineturbine to to

generate electricity.generate electricity.• Cold deep-ocean water will Cold deep-ocean water will

condensecondense the steam. the steam.• The steam turns into The steam turns into waterwater that can that can

be used again. be used again.

OTEC Video

Renewable Energy Renewable Energy Pro’sPro’s1.1. No shortage of renewable energy from the No shortage of renewable energy from the sunsun, , windwind

and and waterwater and even stuff usually thought of as garbage and even stuff usually thought of as garbage ((biomassbiomass). ).

• Sunlight falling on U.S. in one day contains more than Sunlight falling on U.S. in one day contains more than 2X energy we consume in an entire year. California has 2X energy we consume in an entire year. California has enough wind gusts to produce 11% of enough wind gusts to produce 11% of world'sworld's wind electricity) wind electricity)

2.2. Less Less pollution pollution

3.3. Renewable energy resource development Renewable energy resource development new new jobsjobs for people and less oil we must buy from foreign for people and less oil we must buy from foreign countries countries

4.4. Continued research has made renewable energy Continued research has made renewable energy more affordablemore affordable than 25 years ago. than 25 years ago.

• Cost of wind energy has dropped from 40¢ per kilowatt-hour to Cost of wind energy has dropped from 40¢ per kilowatt-hour to less than 5¢. Cost of solar electricity, through photovoltaics has less than 5¢. Cost of solar electricity, through photovoltaics has dropped from more than $1/kilowatt-hour in 1980 to dropped from more than $1/kilowatt-hour in 1980 to 20¢/kilowatt-hour today.20¢/kilowatt-hour today.

Renewable Energy Renewable Energy Con’sCon’s1.1. Takes up a Takes up a lot of landlot of land::

• Solar thermal energy (huge mirrors) needs large tracts of land Solar thermal energy (huge mirrors) needs large tracts of land as a collection site. as a collection site.

• Average wind farm requires 17 acres of land to produce one Average wind farm requires 17 acres of land to produce one megawatt of electricity, enough electricity for 750 to 1,000 megawatt of electricity, enough electricity for 750 to 1,000 homes. However, farms and cattle grazing can use the same homes. However, farms and cattle grazing can use the same land under the wind turbines. land under the wind turbines.

• The environment is also impacted when the buildings, roads, The environment is also impacted when the buildings, roads, transmission lines and transformers are built. transmission lines and transformers are built.

2.2. A renewable power plant doesn’t release air pollution or use A renewable power plant doesn’t release air pollution or use fossil fuels, it fossil fuels, it cancan still have a still have a negative impact on the negative impact on the environmentenvironment::

• Making PV cells uses toxic chemicalsMaking PV cells uses toxic chemicals• Wind farms cause erosion in desert areas and affect natural Wind farms cause erosion in desert areas and affect natural

views because they tend to be located on or just below views because they tend to be located on or just below ridgelines. Bird deaths also occur due to collisions with wind ridgelines. Bird deaths also occur due to collisions with wind turbines and wires.turbines and wires.

• Dams used in hydroelectric power cause farmland and Dams used in hydroelectric power cause farmland and forests to flood. Downstream, dams change the chemical, forests to flood. Downstream, dams change the chemical, physical and biological characteristics of the river and land. physical and biological characteristics of the river and land.