This device can power your phone in a blackout or when you are camping: ‘When the power is cut, modern life is thrown into disarray. But thanks to a new project you may not have to worry about your smartphone dying. The Candle Charger is described as an “indoor power plant for smartphones,” providing USB charging capabilities with just a candle and five ounces of water.’ http://www.gizmag.com/candle-charger/38461/ Also see: http://www.gizmag.com/flamestower-fire-charger/29290/
Update: Now available from here: http://stowerenergy.com/product/candle-charger/ for US$89.99.
The Candle Charger
I had long ago seen that you could buy the Peltiers here: Peltier + circuit http://www.customthermoelectric.com/powergen.html?gclid=CLTl4JPpxrMCFchbpQodszYAow plus the circuits to stabilise output voltage and provide USB power. I was speculating about simply attaching one to a platypus bottle (of cold water) and sitting it near the fire so that its two sides had different temperatures. Some current must be created. I can see that a metal tongue which will get one side hotter without warming the other side is an improvement on this, but at 198 grams! My simple set-up would weigh perhaps 50 grams. Still on my To-Do list. If there are others out there with a little more electronic nous than me who want to get into this, please message me.