Free energy from cars
Remember when you played teeter-totter as a kid? That is a simple machine that you powered with your weight. We can hardness the energy created by the weight of the cars running on a highway by a series of mechanical, hydraulic, or air pressures systems. The individual device would be small enough so the drivers would not feel anything. Then they will be combined into one to run a turbine to produce electricity. Imagine if all the highways were filled with this system! They would produce enormous electricity.
Reward: Name it with my name.