On the Mountain Men show and also one of those alaska shows they generate small amounts of electricity from streams. They funnel it through pipes and use the water to power a generator. Of course this requires a fast moving source of water but its an option.
After decades of cogitation on the subject, the only way I can see to get off of the grid is to burn alcohol that you produced yourself in a regular internal combustion engine powered generator. You would need a large distillery that produced 100 gallons a day(that’s a lot of alchohol) and it would not be a small operation but it would be doable. You could sell electricity to your neighbors to offset costs. Drinking the fuel is not advised.