Chapter 12 Renewable Energy and Conservation

Renewable Energy Sources Those that are replenished by natural processes and can be used “indefinitely”. Examples include; Solar energy Wind energy Hydropower Biomass energy Wave Energy and Tidal energy Ocean Thermal energy Geothermal energy

Alternatives to fossil fuels Are currently not utilized to their full potential due to competition with traditional forms of energy ($$$fossil and nuclear $$$)

Hybrid Cars In Italy

Using alternatives to fossil fuels and nuclear power. Hybrid Car In Italy

Solar energy The most attractive renewable energy source. Direct: heats water, buildings, generates electricity. Indirect: wind, biomass, and hydropower.

Solar energy Heating buildings and water tanks. Passive solar heating: uses building designs to heat buildings without fans or pumps. South facing windows in the Northern Hemisphere. Active solar heating: uses collection devices to gather solar energy (Infrared rays).

Solar energy Photovoltaic cells (PV) convert sunlight  electricity. (Silicon or gallium arsenide are used to generate a flow of electrons) flow of electrons = electricity

Solar energy Solar Thermal Electric Generation: This system heats a liquid  steam  spins a turbine  electricity. Use natural gas Back-ups at night or cloudy conditions. Mojave Desert and Whit Cliffs (Australia)

Solar Collector

Wind energy The most competitive renewable energy source. A form of indirect solar energy  becomes mechanical energy (movement of air). Costs have declined from $.40 to $0.05 per kilowatt hour.(kWh) (1999) Wind Farms use wind turbines to to generate electricity. Found in the U.S. (Great Plains), Denmark, India, and Germany. Clean and Ugly (NIMBY). “bird killing has dropped.”

Hydropower Water flows back to the sea (hydrologic cycle) Concentrated flow (Dams convert Potential energy to kinetic (movement) energy. 20% of world’s energy. U.S plants produce 10% of electricity. Change in river flow (reservoirs destroy habitats and property) spawning fish are disrupted (Salmon) Arid regions lose a lot of H 2 O through evaporation.

Wave Energy Winds produce waves in the ocean and have the potential to turn turbines and generate electricity. Air flow from the waves drives the turbine. Osprey plant in Scotland was demolished by a storm one month after it was operational. 

Tidal energy Bay of Fundy in Nova Scotia has huge differences in high and low tides. Dams are constructed to trap high tide water and drain it as the tides recede (turbines produce electricity). Not an option for many areas due to the tide levels.

Biomass energy Oldest human fuel source. Indirect form of solar energy uses wood and fast growing plants to produce energy. Solids –Such as wood, charcoal, dung, buffalo chips, and peat moss. Liquids- Include Methanol (Methyl Alcohol), or Ethanol (Ethyl Alcohol) both inefficient to make. Gases-Methane (Swamp gas)

Ocean Thermal energy Ocean temperature gradients can generate electricity. OTEC or Ocean Thermal Energy Conversion pumps warm surface water into a powerplant  Ammonia is boiled(BP –33°C)  Ammonia steam drives a turbine  electricity is produced. Ammonia is then cooled by the deep cool water and process begins again.

Geothermal energy The most widely used of the non-solar renewable energy sources. GHP’s or Geothermal Pumps take advantage of the temperature gradients in the earths surface. Provide heat in the winter and store heat (heat sink) in the summer. Hydrothermal reservoirs use steam to generate electricty.

Energy Conversation is the key! Moderating or eliminating wasteful energy activities, and demanding government support for alternative fuels.