VI. Tidal Power

A. Definition 1. Can use rising and falling tides to create electricity 2. Build dams across narrow inlets a. As tide comes in, spins turbine b. Some are now capable of spinning in both directions 3. Floating turbines are use to harness wave energy a. Nearer to shore, become stationary

B. Problems 1. Main criticisms are harm to wildlife and spoiling of scenery 2. Large dams block access to bays by animals and humans 3. Other turbines are eyesores to tourists

C. Thermal Energy of Oceans 1. Called Ocean Thermal Energy Conversion (OTEC) 2. Take solar energy absorbed by ocean, pumps water into facilities that use heat to evaporate ammonia a. Steam  turbine  generator  electricity 3. In an open cycle, water itself is evaporated to create steam a. This desalinates water

VII. Geothermal Power

A. Description 1. One of only energy sources not from sun 2. Radioactive elements decay generating heat which melts rock that rises to the surface 3. In some places, heat boils water, which rises to the surface as geysers 4. Geothermal plants use steam to turn turbines a. Produces clean energy

5. Can also pump steam to surface using radiant energy to heat homes a. Water is piped into ground where it is heated and cycled up to go through floors of homes b. Also acts to cool homes in summer 6. Not used much but growing

B. Disadvantages 1. As Earth shifts and water supplies dwindle, may not be sustainable 2. By accessing, can release toxins 3. Limited places can use 4. Hard to repair- can’t throw a switch to shut it down