Environmental ScienceEnvironmental Science

Renewable/Alternative Renewable/Alternative Energy SourcesEnergy SourcesLecture NotesLecture Notes

Biomass EnergyBiomass Energy Biomass = garbage from Biomass = garbage from

organisms organisms Dead trees, branches, yard Dead trees, branches, yard

clippings, left-over crops, wood clippings, left-over crops, wood chips, bark and sawdust from chips, bark and sawdust from lumber mills (even manure)lumber mills (even manure)

Trash that can't be recycled Trash that can't be recycled landfill landfill using biomass for fuel using biomass for fuel cuts down landfill spacecuts down landfill space

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

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

How biomass works: How biomass works:

1. Biomass collected in trucks 1. Biomass collected in trucks taken to biomass power plant taken to biomass power plant

2. Biomass burned 2. Biomass burned boils water boils water steam turns turbogeneratorssteam turns turbogenerators

Landfill GasLandfill Gas Biomass also “tapped” at landfills Biomass also “tapped” at landfills

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

gas gas 2. Pipelines collect methane gas 2. Pipelines collect methane gas

burned burned in power plants to make in power plants to make electricityelectricity

Also done on animal farms: Manure Also done on animal farms: Manure decomposes decomposes methane gas methane gas burned at burned at farm to make energyfarm to make energy

Using biomass does NOT add to global Using biomass does NOT add to global warming (unlike fossil fuels). WHY NOT?? warming (unlike fossil fuels). WHY NOT?? Turning Landfill Gas into Energy (4")

The Future of BiomassThe Future of Biomass

Biomass is Biomass is renewable renewable because because plant biomass can be regrownplant biomass can be regrown

Another use of biomass is ethanol, Another use of biomass is ethanol, a liquid alcohol fuel a liquid alcohol fuel – Ethanol used in cars designed to use Ethanol used in cars designed to use

alcohol fuel instead of gasoline alcohol fuel instead of gasoline – Alcohol can also be mixed with Alcohol can also be mixed with

gasoline to reduce dependence on oilgasoline to reduce dependence on oil

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

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

• For every 328 feet below ground, temperature ↑5.4oF. At 10,000 feet below ground, the temperature is hot enough to boil water.

• Deep under the surface, hot water can reach temperatures more than 300oF (water boils at 212oF). It doesn't turn to steam because it is not in contact with the air.

• What are geysers? (Old Faithful pictured on the right)

Geothermal Today Geothermal Today In U.S., geothermally heated water is used in

swimming pools and health spas In Southern California, hot water from

underground is used to heat buildings during winter. Hot water runs through miles of insulated pipes to public buildings.

In Iceland, many buildings/swimming pools are heated with geothermal hot water. The country has at least 25 active volcanoes and many hot springs and geysers.

Geothermal Heating (1")

Geothermal Electricity Geothermal Electricity Underground steam Underground steam electricity in electricity in

geothermal power plantgeothermal power plant1. Holes drilled in ground & pipes 1. Holes drilled in ground & pipes lowered into steamlowered into steam2. Steam comes up pipes 2. Steam comes up pipes 3. Steam spins turbine blades 3. Steam spins turbine blades

and and generator to make electricitygenerator to make electricity4. Steam cooled off in cooling 4. Steam cooled off in cooling tower and pumped back tower and pumped back

underground to be reheated by underground to be reheated by earthearth

California's geothermal power plants California's geothermal power plants produce about 1/2 of produce about 1/2 of world'sworld's geothermally generated electricity geothermally generated electricity (enough for 2 million homes) (enough for 2 million homes)

Geothermal Electric Power Plant (4.5")

Hydro Power Hydro Power Moving water kinetic energy electricity

First used to turn wooden wheels First used to turn wooden wheels attached to grinding wheels to grind (or attached to grinding wheels to grind (or mill) flour or cornmill) flour or corn

Water can either Water can either go over the top of the go over the top of the wheelwheel (see photograph at right), or (see photograph at right), or the the wheel can be placed in the moving wheel can be placed in the moving riverriver. The flow of the river turns the . The flow of the river turns the wheel at the bottom (see moving wheel at the bottom (see moving graphic in the upper right) graphic in the upper right)

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 or reservoirs and along rivers

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

How a Hydro Dam WorksHow a Hydro Dam Works 1. Water behind dam flows 1. Water behind dam flows

through intake pipe called through intake pipe called penstock. penstock.

2. Water pushes against 2. Water pushes against blades in a turbine. blades in a turbine.

3. Turbine spins generator 3. Turbine spins generator to produce electricity. to produce electricity. Electricity travels via Electricity travels via electric lines to homes, electric lines to homes, schools, factories and schools, factories and businesses.businesses.

Hydroelectricity (2")

Ocean Energy

3 basic ways to tap the ocean for its energy:

1. ocean's waves

2. ocean's high and low tides

3. temperature differences in the water

Wave Energy

Moving waves Kinetic energy Wave turbine:

1. Wave rises into chamber2. Rising water forces air out of chamber3. Moving air spins turbine to turn a generator4. When wave goes down, air flows through turbine and back into chamber through doors

that are normally closed Most wave-energy systems are very small and can be

used to power a warning buoy or small light house

Wave Energy Video

Tidal Energy

Tides come into shore and are trapped in reservoirs behind dams. When tide drops, water behind dam is let out just like a hydroelectric power plant

An increase of at least 16 feet between low to high tide is needed for tidal energy to work

Only a few places where this tide change occurs around the earth. One plant in France makes enough energy from tides (240 megawatts) to power 240,000 homes.

Tidal Electricity Generation Animation (1")

Ocean Thermal Energy Conversion (OTEC)

Uses temperature differences in ocean Sun warms surface water more than deep

water Ocean's warm surface water is used to heat a

fluid with a low-boiling point, such as ammonia

Steam turns turbine activates generator to produce electricity

OTEC Video (4")

Renewable Energy Pro’s

1. No shortage of renewable energy from the sun, wind and water and even stuff usually thought of as garbage (biomass). (Sunlight falling on the United States in one day contains more than twice the energy we consume in an entire year. California has enough wind gusts to produce 11 percent of the world's wind electricity.)

2. Less pollution

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

4. Continued research has made renewable energy more affordable than 25 years ago. (The cost of wind energy has dropped from 40¢ per kilowatt-hour to less than 5¢. The cost of solar electricity, through photovoltaics has dropped from more than $1/kilowatt-hour in 1980 to 20¢/kilowatt-hour today.)

Renewable Energy Con’s

TAKES UP A LOT OF LAND:1. Solar thermal energy (often huge mirrors) needs large tracts of land as a collection

site. 2. Average wind farm requires 17 acres of

land to produce one megawatt of electricity, enough electricity for 750 - 1,000 homes. However, farms and cattle grazing can use the same land under the wind turbines.

3. Environment also impacted when constructing power plants, roads, transmission lines and transformers.

EVEN THOUGH A RENEWABLE POWER PLANT DOESN’T RELEASE AIR POLLUTION OR USE FOSSIL FUELS, IT CAN STILL HAVE A NEGATIVE IMPACT ON THE ENVIRONMENT:

1. Making PV cells uses toxic chemicals.

2. Wind farms could cause erosion in desert areas. Most often, winds farms affect the natural view because they

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

3. Dams used in hydroelectric power cause farmland and forests to flood. Downstream, dams change the

chemical, physical and biological characteristics of the river and land.