http://www.eere.energy.gov/kids/
Interesting site looking at ways children can save energy in their own environment. Also includes simple, clear explanations about different types of renewable energy. Dozens of lesson plans for all primary age groups.

http://www.alliantenergykids.com/stellent2/groups/public/documents/
pub/phk_ee_re_index.hcsp
Child-friendly site looking at all forms of energy. It focuses on energy basics, safety and the environment. The site includes fun and games, and resources for teachers and parents.

http://www.solarenergy.org/resources/youngkids.html
All about solar energy.

http://www.eia.doe.gov/kids/energyfacts/index.html