Instructables user scraptopower designed a thermoelectric lamp that can convert heat into small amounts of electricity. One of the best uses for this is building an LED lamp that runs from tea candles.
Yes, candles generate usable light, but if you've ever tried reading by one of them you might appreciate a more powerful light source during a blackout or camping trip without having to worry about batteries.
The thermoelectric lamp is an LED light powered by two individual devices, a Peltier cooler and a joule thief. A 100-watt peltier thermoelectric cooler is normally used to cool down computer processors, but in this application it is used with a copper/aluminum heatsink to generate electricity from the temperature difference between the heat generated by the candle and the cool surface of the heatsink. A joule thief is a circuit that boosts voltage from the power source—they are most popularly used in battery-operated cell phone boosters. The Peltier cooler generates small amounts electricity and the joule thief pulls a little more voltage than what would normally be supplied from the cooler to power the LED lamp.
Following the guidelines on Instructables you'll spend around $60 in source materials for this project, which was wired so that it can also power other small items such as radios. The only actual electronics work is attaching your LED lights and joule thief to the Peltier cooler and this can be done without a soldering iron in a pinch. If you love the idea but have no desire to build one for yourself you can purchase a premade unit from Ubertechnics.
How to build a thermoelectric lamp [Instructables]