Fluctuation Powered Engine

The FPE is a human-powered engine. A person pushes the two pistons so that the flywheel rotates. The flywheel makes the output shaft smooth and free of fluctuation.

You can use this to save electricity, especially from 12pm to 6pm, when electricity comes from burning fossil fuels and gasses. You save electricity because it is entirely human powered and the fluctuation motion increases torque on the output.