26.2 Alternative Energy Resources Pages

Objective 1.0 Describe 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