Jet Engine Energy Recycle
The basic idea is to harness the energy created from the thrust of a commercial jet engine. You would place another turbine behind the main turbine that is propelling the jet forward, except this turbine will not be pushing it forward, instead it will be harnessing the energy created from the thrust of the main engine. As the main turbine is powered by the engine and is running, it creates a powerful stream of air that will turn the second turbine and still let the air flow through. It may lose a minuscule amount of thrust, so it will not make much of a difference in regards to power. Thus, as the second turbine turns, it will create energy that could be fed back into the plane to power anything, like possibly the electronics in the plane(A/C, lights, t.v., etc.).
Reward: Free travel on whatever airline uses this idea.