Science fair projects are meant to solve problems, not to show how something works. I'd like to do a science fair project in the category of engineering using my LEGO Mindstorms robotics kit. The judges at the science fair especially like environmental projects, so I want to do an environmental engineering project. An example would be "What alternative energy source is the most efficient: water, wind, or geothermal?" Something like that would be good. If you have any ideas, I would greatly appreciate to see them.