Chemical engineering

They'd be doing the mechanical design of the turbines, the electrical engineers would rig up all the stuff (sorry for the **** description), but it's chemical engineers that are specialized in energy. Practically all we study is fluid mechanics (air is a fluid, remember, you need to know that really well for wind turbines), thermodynamics (heat transfer is important when generating energy) and all sorts of process design to do with incorporating power and energy inputs and outputs, exactly what you're looking at with any sort of power-generating device.