We run a dehumidifier every day during winter to take moisture out of the air so we don't encourage mould in the house. I've been thinking about how else that could be powered.
picture from here .
I think it could work if I had a pull cord with a handle at the top of the stairs. As people go down the stairs they could pick up the handle, pull it with their weight as they go down the stairs, and then let it go when they get to the bottom of the stairs. The pull cord could transfer energy to a flywheel which would be used to power the fan or charge a capacitor if the fan is not running.
This would be more sustainable because the energy for running the unit would come from mechanical energy provided by the humans in the house instead of relying on electricity supplied across the grid. Our electricity comes from wind turbines
but we still use too much of it and need to cut down. It's inefficient to move energy across the grid, a lot is lost in transmission so the more we can replace with better more local power sources the better.
Another development to solve the damp problem could be to build a heat exchange ventilation unit
into the wall, and use this pull cord mechanism to power it. I'll save up!