Hydroelectric power project

[HopePressler1]

My daughter wants to use hydroelectric power in her next science fair project. She thought about using a dam that beavers built near our house or the flow of a stream near our house as the source of water. She isn't sure whether this project would be better as an engineering design project or a traditional scientific method project. Do you have a suggestion?

If it is a traditional scientific method project would a legitimate question be which type of water turbine would create the most electricity? She thought possibly of using a pelton wheel type turbine or an Archimedes screw type turbine. I was concerned there would be a lot of variables changing if entirely different turbines are used unless the entire turbine could be seen as a single variable.

Any suggestions are appreciated.

Thank you,
Hope

[bfinio]

Hi - there are a few different ways you can compare different types of generators, but you can't just look at the total electrical output since, as you pointed out, that wouldn't really be an apples-to-apples comparison. One method is to look at the efficiency of each generator - what percentage of the total input mechanical energy (in this case, flowing water) is converted to electrical energy? Another method is to look at the cost of the resulting electricity, just like you would with a real electrical bill. If you look at your electric bill you will probably see a price in $/kWh - dollars per kilowatt-hour. While this includes a bunch of other factors (like transmission charges - the cost for actually getting the electricity from the power plant to your house), for a science project you could do it based on the cost of the materials to build each type of generator. It would probably be harder to do for the time scale of a science project, but you could also look at maintenance/durability - is one type more likely to break, get clogged, additional cost for replacement parts, etc? These are the same metrics we can use to compare different power sources (wind, solar, fossil fuels, etc).

Hope that helps, please write back if you have more questions!