Chapter 12Renewable 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)

http://www.industrialsolartech.com/05644Beck.jpg

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. 1200 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 H2O 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.