Alternative Energy Sources

 Solar  Geothermal  Hydroelectric  Wind

Solar Power-15 minutes of sun could power the world for 1year

Types of Solar Power  Active –Involves the use of solar collector –photovoltaics  Passive –No working parts –Uses sunlight directly –When sun shines in the window it warms the room

Active Solar Power  Solar Collector  Heats water as it passes through tubes.  Water is used to heat buildings or preheat water heaters

Active Solar Power  Photovoltaics  Sunlight collected by panels is converted to electricity  Electricity can be sold back to the utility company

Large-scale Solar Electric Site

Solar Power  Benefits –Abundant –No greenhouse gases, few other pollutants –Simple, minimal repair needed –Cheap over the long term  Detriments –Retrofitting needed if structure is not already designed as passive solar –Has limitations, night, some locations better such as south rather than north facing slopes –Initial investment cost can be a lot.

Solar Video Clip

Geothermal Energy

Geothermal - How does it work?  Drill to deep, hot rock –Either wet system heated water below ground is used –Dry system sends above ground water belowground to get heated  Resulting steam can be used for a number of purposes

Geothermal Energy  Steam can be used as heat  Steam can drove turbines to generate electricity  Used by –San Francisco –Iceland –Italy –Japan

Geothermal Video Clip

Hydroelectric  Energy produced by running water  11% of power in US  Dam holds back water  When released it produces energy

How hydropower works

New Melones Powerplant

Negative effects of Hydropower  Flooding the land  Loss of species (aquatic & terrestrial)  Loss of normal nutrient flow down river  Changes temperature of water, too

Tidal Power  Dams are built to trap water at high tide and release at low tide. Tidal dam

Positive Effects of Hydropower  Can generate electricity  No greenhouse gases  Initial construction provides jobs

Hydropower Video Clip

Wind power  Can be used for mechanical tasks, e.g. pumping water  Can be used for generation of electricity for direct use or storage in batteries  Cannot depend on wind energy alone

Electrical Power Windmills  High speed, low torque machines  Will turn themselves off if wind speed exceeds their limits

Altamont Pass Wind Farm  Between Livermore and Tracy  4800 small wind turbines  One of the oldest in US

Effects of windpower  No greenhouse gases  Few other pollutants  Cheap  Abundant  Simple  Some noise pollution  Metal blades interfere with TV & radio reception  Aesthetic pollution  No evidence for bird death, but can kill bats Positive Negative

Wind Video Clip