Here are some links Ms. Sylvia found to help you research different forms of power:
http://www.tvakids.com/index.htm
http://education.nationalgeographic.com/encyclopedia/renewable-energy/
http://www.eia.gov/kids/energy.cfm?page=renewable_home-basics
http://www.fplsafetyworld.com/?ver=kkblue&utilid=fplforkids&id=16182
http://www.sciencekids.co.nz/sciencefacts/energy/nuclearpower.html
Solar advantages and disadvantages
Nuclear power advantages and disadvantages
More nuclear power advantages and disadvantages (easier)
Advantages and disadvantages of wind power
More advantages and disadvantages of wind power
NEW LINKS:
Nuclear Power: CO2 explanation and disposal of nuclear waste:
http://tiki.oneworld.org/energy/energy7.html
A video about disposing of nuclear waste:
https://www.youtube.com/watch?v=GlEtQ2qlxEU
Costs of all types of electricity (Mr. Connelly will help you to interpret this table):
http://www.eia.gov/forecasts/aeo/pdf/electricity_generation.pdf
Pros and Cons of Coal:
http://www.triplepundit.com/special/energy-options-pros-and-cons/clean-coal-pros-cons/