1. Solar Wind Hydro electric Biomass

2. Solar Power

3. 48) The sun is the major source of energy for phenomena on the Earth's surface, including winds, ocean currents, and waves.

4. 49) Solar electricity can be produced in photovoltaic cells that can be placed on rooftops and other sunny places.

5. 50) A photovoltaic cell makes energy by changing solar radiation into electricity.

6. 51) The cost of photo voltaics continues to drop dramatically, but they are still several times as expensive as the cheapest electricity.

7. 52) The sun's energy can be used economically without conversion to electricity. Some uses are to heat water for home use, and to heat and light buildings designed to take advantage of the sun's path through the sky

8. 53) Solar energy does not require the use of turbines.

9. 54) Solar energy produces less pollution than any other method of energy production.

10. 55) The biggest problem with solar energy is the cost of storing the energy.

11. Wind Energy

12. 56) Wind electricity is produced by turbines which can be grouped together on a "wind farm."

13. 57) Wind electricity is cost-competitive with other forms of electricity.

14. 58) Only certain parts of the country such as the Great Plains states have enough strong, steady wind for widespread wind power development.

15. 59) The lack of locations of sufficient winds for wind turbines is the biggest problem wind energy.

16. Hydro Electric Power

17. 60) Hydroelectricity is produced by turbines below dams
60) Hydroelectricity is produced by turbines below dams. The turbines are moved by moving water.

18. 61) Hydroelectricity is inexpensive.

19. 62) Hydroelectricity is the most widely used form of renewable energy.

21. 63) The best sites for hydroelectricity in the U. S
63) The best sites for hydroelectricity in the U.S. have already been dammed, and further dams would have to displace valuable urban and farm land.

22. 64) New hydroelectric power plants in the United States are unlikely to occur because there is a lack of locations where the construction of dams is feasible.

23. 65) Dams can cause damage to the environment by ruining ecosystems for plants and animals by flooding.

24. Biomass and Other Energy Resources

25. 66) Biomass is the energy production that comes from burning organic material that were recently harvested.

26. 67) Ethanol is a combustible liquid made from plants that can be burned to make energy.

27. 68) Two problems with biomass are air pollution and use of too much land.

28. 69) Heating water from magma intrusions to make electricity is called Geothermal.

29. 70) Geothermal energy is heat energy that originates from within Earth and drives the movement of Earth’s tectonics’ plates.