Expert: Paul Soderman - 9/30/2008

Question
I am building a solar electric car and want to also attach a wind turbine (obviously I am trying to create a car that uses no fossil fuels). I was told that there is little point because the wind drag created by the wind turbine would neutralize almost all of the electricity created. is this true in your opinion.

Answer
Ben
If you were capturing natural wind you might be able to generate much more electrical energy than you would lose in drag.  But I suspect you are trying to capture the wind energy generated by the car's motion.  In that case the drag on the wind turbine times the car speed would be the power it would take to drive the wind turbine.  It would also be the maximum power that the wind turbine generates.  And with losses, you would actually be losing energy.  So the loss to your car's kinetic energy would be greater than the energy generated by the turbine.  Remember, energy in a system cannot be created or destroyed, it can only be transformed from one type to another.  In your case, you would be transforming the solar energy into kinetic energy of the car, part of which would go into wind energy of the turbine and into electrical energy which, I assume would be stored in a battery. You would be better off going directly from solar energy to the battery.  I hope I understood your plan correctly.
Paul