1. Chapter 11 Section 2: Renewable sources of energy
Key Concepts:
What forms of energy does the sun provide?
What are some renewable sources of energy?
Key terms:
Solar energy, hydroelectric power, biomass fuel, gasohol, geothermal energy

2. Renewable sources
Solar
Water
Wind
Biomass
Geothermal
Hydrogen

3. Sun’s energy Solar energy – energy from the sun
The sun constantly gives off energy in the forms of heat and light
It’s hard to use the sun’s energy because:
Only useful when it’s shining
Widespread, so hard to harness a lot of it within a small area

4. Solar stuff
Solar Power Plants – use giant mirrors to heat water to steam
Solar cells – like a battery. Light hits it and electric current is produced. Takes a lot of them.
Passive Solar Heating – converts sunlight into thermal energy
Active Solar Heating – captures energy on a dark metal surface of a solar collector, converts it to thermal energy

5. Hydroelectric power
Hydroelectric power is electricity produced by flowing water
Flowing water can move turbines, just like steam or wind, and create an electric current
Hydroelectric is the most widely used form of renewable energy
Requires a dam, which can affect ecosystems
Inexpensive and no air pollution, once dam is built

6. Capturing Wind Wind energy is an indirect form of solar energy
Wind is caused by uneven heating of the earth by the sun
Wind can be used to turn a turbine
Does not cause air pollution, but can be noisy and ineffective. AND the metal to make the turbine has to be mined and then processed into steel. Very few people mention that the MAKING of “green energy” materials are very un-green.

8. Biomass fuels Biomass fuels are made from living things
The best example is wood
Leaves, food wastes, manure
Can be burned or converted to other fuels
For example, corn, sugar cane, and other crops can be used to make alcohol
Adding alcohol to gasoline makes gasohol, which can be used as car fuel
Bacteria produce methane when they decompose biomass, and the methane can also be captured and used as fuel
Biodiesel fuel – oil produced by some crops
Drawbacks: takes time, expensive

9. Tapping Earth’s Energy
Intense heat from Earth’s interior is called geothermal energy
In CERTAIN (not everywhere!) areas, like Iceland and New Zealand, magma heats underground water to boiling. Hot water and steam can be valuable energy sources.
Disadvantages: doesn’t work everywhere, requires deep drilling

10. Promise of hydrogen power
Pure hydrogen can be obtained by passing electricity through water
Takes more energy to obtain the hydrogen than it produces