Aluminum Can, Saltwater and Charcoal Battery

http://www.instructables.com/id/Aluminum-Can-Saltwater-and-Charcoal-Battery/

This instructable shows how to create a simple aluminum air battery from a soda can and a piece of charcoal from the backyard BBQ. This instructable is being published early but I hope to combine this device with a joule thief and an LED to provide a rechargeable backyard lighting system that can be emptied and refilled.

I believe that well burned campfire charcoal could also be used. Backpackers could have an extremely lightweight, wholly renewable and non CO2 generating light source.

From Wikipedia:Aluminum Air Battery
Aluminium batteries or aluminum batteries are commonly known as aluminium-air batteries or Al-air batteries, since they produce electricity from the reaction of oxygen in the air with aluminium. They have one of the highest energy densities of all batteries, but they are not widely used because of previous problems with cost, shelf-life, start-up time and byproduct removal, which have restricted their use to mainly military applications. An electric vehicle with aluminium batteries could have potentially ten to fifteen times the range of lead-acid batteries with a far smaller total weightt

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