1. 16.3 – Renewable Energy Sources

2. Objectives Analyze the need for alternative energy sources.
Compare the advantages and disadvantages of various alternate energy sources
Describe alternate methods for generating electricity.

3. Renewable resource Can be replaced almost as quickly as it is used
Example: Because only about one billionth of the Sun’s energy falls on Earth, and because the Sun is expected to continue producing energy for several billion years, solar energy cannot be used up

4. Solar Energy
Converted into electricity by a photovoltaic cell, or solar cell
A solar cell contains one layer of electron-rich semiconductor material and one layer that is electron-poor

5. Solar cells
Energy produced by solar cells is more expensive than energy produced with fossil fuels
Energy from solar cells must be stored in batteries when the sun is not shining

6. Hydroelectricity Produced by moving water
It is about twice as efficient as fossil fuels or nuclear power

7. Tidal energy Uses moving water
As the tide comes in, the moving water spins a turbine that generates electricity
The water is then trapped behind a dam
At low tide the water behind the dam flows back out to the ocean, spinning the turbines and generating electric power

8. Tidal energy
It can only be used in places when high and low tides are different enough

9. Windmills Can be used to generate electricity
Wind spins a propeller that is connected to an electric generator
Only useful when the wind blows consistently

10. Geothermal energy Thermal energy contained in hot magma
Limited to areas where magma is close to the surface

12. Alternative fuels Hydrogen gas
It produces only water vapor when it burns and creates no pollution

13. Alternative fuels Biomass = renewable organic matter
Such as wood, sugarcane fibers, rice hulls, and animal manure
Burned in the presence of oxygen to convert the stored chemical energy to thermal energy

14. In-Class Assignment/Homework
Missed Conception” – students will discuss certain misconceptions that people have about energy and explain why those misconceptions exist
16.3 WKT
Directed Reading WKTs