Ch. 18.2 Alternative Energy & Conservation

A. Alternative Energy Energy sources that are still in development. They require further research to see if they are cost-effective and non-polluting.

B. Tidal Power Tides – movement of water in the oceans and seas caused by the gravitational attraction between the sun, Earth, and moon.

B. Tidal Power Tides change twice each day, and this energy can be used to turn turbines. Similar to a hydroelectric dam

B. Tidal Power Used nearly a thousand years ago to power mills in France and Britain Currently used in France, Russia, and Canada to generate electricity.

B. Tidal Power Disadvantages: Expensive to build and maintain Few suitable locations available

C. Ocean Thermal Energy Conversion (OTEC) Natural temperature differences occur in the tropics, with warm surface waters and cold deep waters. Warm surface water is used to create steam Cooled off by cold deep waters

C. Ocean Thermal Energy Conversion (OTEC) The steam turns a turbine to generate electricity. Currently being experimented with in Japan.

C. Ocean Thermal Energy Conversion (OTEC) Disadvantages: Not cost-effective The power needed to pump cold water up from the deep ocean used one-third of the electricity the plant produces Possible environmental consequences

D. Hydrogen The most abundant element in the universe When burned, it forms water vapor. Possible fuel cells used in cars

D. Hydrogen Disadvantages: Water vapor is a major greenhouse gas Requires much energy to produce

E. Energy Efficiency (EE) The percentage of energy put into a system that does useful work EE (%) = energy out x 100 energy in

E. Energy Efficiency (EE) Most energy that is lost is in the form of heat. Most inefficient machines: internal combustion engines Hybrid cars are much more efficient

F. Energy Conservation Saving energy Everyone’s responsibility By turning off lights, unplugging appliances, and carpooling, bicycling, or walking, you can save a lot of energy!