26.2 Alternative Energy Resources

Pages 690 - 697

Objective 1.0Describe alternative energy

resources

• 1.Solar energy– Advantages

• Freely available• No pollution

– Disadvantages• Nighttime• Cloudy days• Difficult to store solar energy

• Passive solar heating– Building materials store and release heat

• Concrete• Adobe• Brick• Stone• Tile

• Active solar heating– Solar panels

• absorb energy• Heat water• Stores energy as heat in rock or water

tanks

• Solar cookers– Reflective materials concentrate sunlight to

heat pans

• Photovoltaic cells– Convert sunlight energy to electrical energy

• 2. Energy from Water

– Advantages

• Little pollution

• Recreation

• Drinking water

• Irrigation

– Disadvantages

• Sediment accumulation above dam

• Stream bed erosion below dam

• Water quality degrades

• Environmental effects

• Hydroelectric dams– Water moves past turbines– Turbines turn a generator– Generator produces electricity– 20% of world’s electricity– U.S. 10% of electricity– Canada 70% of electricity

Image is PD-gov, by TVA

• Barrier / tidal dams– Use of ocean waves

• Wave action moves a lever arm• Lever arm turns turbines of generator

– Use of tides• Trapped tidal water is released over

turbines

• 3. Geothermal energy

– Advantages

• Abundant and reliable at geothermal sites

– Disadvantages

• Storage of cooled water

• Air and water pollution

• Disrupts ecosystems

• Hard to transport geothermal energy

• Geothermal steam plant– Steam from vents turn turbines

• 4. Wind energy– Advantages

• Readily available at favorable sites• Cheap• Easy to build• Pollution free

– Disadvantages• Steady winds needed

• Wind Farms– Flat, windy areas– Use of wind turbines to generate

electricity

• 5. Nuclear energy– Advantages

• No air pollution

– Disadvantages• Expensive, time consuming to build• Time limits on nuclear plant operation• Radioactive materials • Waste product storage

• Nuclear power plants– Nuclear fission reaction releases heat– Water turns to steam– Steam turns turbines to generate electricity– Water recycled

Boiling Water Reactor

A Typical Power Plant

• 6. Biomass – Advantage

• Renewable– Disadvantages

• Air pollution

• Biogas– Gas + methane mixture– Bacteria in a “digester” container create

methane– Methane piped into home for burning

• Ethanol and Methanol– Grain alcohols from crops– Used in gasoline “gasohol”– Extend gas supplies

• 7. Oil shale and Tar Sand– Advantages

• Supplies petroleum-like substance

– Disadvantages• Processing is expensive• Air and water pollution

• Oil Shale– Kerogen substance found in oil shale– Kerogen vaporized then condensed– Result is “shale oil”

Image: PD-gov

• Tar Sand– “Bitumen” found in tar sand– Bitumen is high- sulfur content oil– Can be refined into a type of crude oil

Image: PD-gov