Here is a cool kit that gets your children familiar with green energy options. The Snap Circuits Alternative Energy Kit lets you try 125+ projects investigating alternative energy strategies. The kit includes over 40 pieces. You get snap wires, slide switchers, wind fan, rechargeable battery, and other parts to get started.
The kit comes with a manual with over 100 pages. It is designed for kids 8 years old and up. Costs under $50.