OK remembering that every little bit of knowledge we can have about the basics in creating energy will greatly be valuable. Remember that even one light bulb that can be ran with out light, wind, or fuel may be a very valuable thing.
Basically you fill a bucket with soil, add some water to make mud. Then you but a copper pipe in the mud on one side of the bucket and a zinc (or galvanized) pipe in the other side of the bucket. Add a little salt (will address how to get salt from the sea in another post) and a little vinegar (around a cup each, but it is not needed it just ups the watts) and you get around .20 watts per bucket. The more buckets the more watts. 4 buckets generate as much as a 2 AA batterys. Now I realize big f'n deal. But if there is not power and you can light a bulb with buckets of dirt....That is a big deal.
Here are a few videos
This one is directly in the ground
Ok this is a 7 part one I will just post the first one. Click through to you tube to see the rest of them ok end song for this post is a beatnik type song ....