The concept behind it is to make a galvanic cell that works on either a saltbridge or a sourbridge.
In this case it's a saltbridge, but you could try using plants or wine (sourbridge) to create the same effect.
-things you need:
.led lights low voltage (testing)
.6 plastic bottles (1l)
.6 pieces of copper
.6 pieces of zinc
Step 1: Step 1
put the bottles in a wooden frame so you can move them around easier.
(when you have copper and zinc cut them into 6 pieces that you can clamp onto en put through the bottle neck.
Step 2: Step 2
left bottle above: add 20 gr of copper sulphate
left bottle below:add 20 gr of zinc sulphate
center bottle above:add 20 gr of zinc sulphate
center bottle below:add 20 gr of copper sulphate
right bottle above:add 20 gr of copper sulphate
right bottle below:add 20 gr of zinc sulphate
each bottle wil produce around 2 volt.
when you have this prepared, connect the copper to the red wire, with on the other side zinc so u will have a + and - side.
and put zinc to the dark wire and on the other end copper. you start in the first bottle with copper and the end in the next bottle (zinc) in the second bottle you start again with a red wire that wil end in the next bottle and there you start again with a black wire. this wil create a electric circuit.
(make sure the clamp cables do not touch the water)
Step 3: Step 3
make sure you cover the bottle neck with a plastic or rubber so that you minimalise evaporasion
measure the voltage using a voltmeter, you can test it by using a led that is close to the average volt that is produced.
in the picture you see a 12volt led burning