“new” alternative energy sources

How do energy conscious people feel

about wind power?

They were blown away

SOLAR - from sun’s radiationWIND - from wind

GEOTHERMAL - from heat & heated water below groundOCEAN - from tides & waves

HYDROGEN FUEL CELLS - from hydrogen

Most of the renewable generated electricity is

from hydropower.

SOLAR - if all of sun’s energy that reaches

earth could be captured, we could

meet current humans demands at

a rate of 27 years/day of

sunlight.History: First known thermal solar

collector: 1767First commercial solar water heaters:

1890

Sun-tracking mirrors (heliostats) reflect sunlight to a receiver that heats to the

tower & heats salt to a liquid. Hot salt is pumped to a steam generating system

which turns the turbine . . .

Photovoltaic cells (PV cells)

Convert solar energy into electrical energy using the

photoelectric effect.

Photons (units of light) strike a metal (such as selenium) causing an

electron to be emitted. P-type is positive, N-

type is negative. Electrodes attached

allow electricity to flow.

PASSIVE SOLAR•Windows, walls and floors are made to

collect, store & distribute solar energy.

•Does NOT use mechanical or electrical devices

PROSRenewable if sun is shiningAbundantAllows for local control over powerSolar cookers lessen work loads in developing nationsNo direct greenhouse gas emissions

CONSNot everywhere is

sunnyInitial investment is

high.Takes several years

to pay for itself.

wind power Converts kinetic energy to electrical

energyFastest growing power source today

Wind turbine blades spin a generator

generatordisc brake .

Mostly used in Germany, then the U.S. and Spain.

PROSPROS CONSCONS

Renewable if wind blows

Windy sites need to be near population

centersNo emissions after

installedAesthetics and noise

More local controlBlades may kill birds,

batsCosts low and

dropping after initial investment

High start up cost

GEOTHERMAL ENERGYRadioactive decay of

elements in core creates heat that rises toward

the surface

magma

geyser

Geothermal power plants

Maintains pressure

geothermal pros

RenewableLower greenhouse emissions than

fossil fuelsInexpensive in some areas (Iceland)

ConsHot spots of heated water migrate

Aquifer pressure dropsSalts in water corrode equipment

Limited to geographic regions where heating naturally occurs

Energy from Oceans

Tidal Power: twice-daily tides create water movement that can be used to turn turbines . . . (similar to hydroelectric dam)

Wave Power: Motion at ocean shores can be used to turn turbines . . .

Tidal power plant, estuary of Rance

River, Bretagne, France

water movement

4 times daily

Oahu, Hawaii

OCEAN POWER

PROS: RenewableNo greenhouse gas emissions

CONS: Development takes up coast line that is valuable for other

uses.Could interfere with ecology of estuaries

and intertidal shorelines

How many APES students does it take

to change a light bulb?

None! They’re smart enough to use energy-

efficient compact fluorescent bulbs,

which rarely need to be replaced.