This document discusses various alternative energy sources including hydroelectric power which uses falling water, geothermal energy which extracts heat from the Earth, and how nuclear power plants use nuclear fission to produce energy by splitting uranium atoms. It also addresses the advantages of solar energy in being free and non-polluting as well as wind power's potential to meet 5-10% of a country's electricity demand over the next 50-60 years. Finally, it summarizes how hydroelectric, geothermal, and tidal power contribute energy through releasing water, using hot water, and generating energy from tidal flows.

1. Alternate Energy Sources 4.2

2. Hydroelectric PowerThe power generated by falling water.

3. Geothermal Energy Energy that can be extracted from Earth’s internal heat, for example, natural steam used for power generation.

4. Key ConceptWhat are the advantages of using solar energy?Solar energy has two advantages: the fuel is free, and it’s non-polution.

5. Key ConceptHow do nuclear power plants use nuclear fission to produce energy?In nuclear fission, the nuclei of heavy atoms such as uranium-235 are bombarded with neutrons. The uranium nuclei then split into smaller nuclei and emit neutrons and heat energy.

6. Key ConceptWhat is wind power’s potential for providing energy in the future? Some experts estimate that in the next 50 to 60 years, wind power could meet between 5 to 10 percent of the country’s demand for electricity.

7. Key ConceptHow do hydroelectric power, geothermal energy, and tidal power contribute to our energy resources?Hydroelectric power contributes by releasing water through a dam, Geothermal power contributes by using hot water to turn turbines, Tidal power contributes by generating energy from a bay’s water flow.