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A candle and some water could keep your phone charged in an emergency

A candle and some water could keep your phone charged in an emergency

During a disaster, there are few options for charging the electronic devices that are so important to our modern lives. But now there's one more, courtesy of a company called Stower, and this one depends on very basic elements.

It's kickstarting a 'Candle Charger' that exploits a nifty physics trick to charge any USB-powered device using just fire and water. That trick is the thermoelectric effect - a property of certain semiconductors.

The effect turns a thermal gradient - when one part of the material is hot and the other is cold - into electricity. It's simple, safe, and has been used widely for more than twenty years in cars, fridges and more.

Smart circuit

The tricky bit comes in converting that electricity into a form your smartphone can handle without blowing it up. That's where Stower's innovation comes - creating a "smart circuit" that matches the requirements of whatever's plugged in.

At the time of writing, the company has raised almost $12,000 of a $30,000 goal with 41 days still to go.

If you'd like to get hold of one (bundled with a six-hour candle), you'll need to pledge at least $65. Delivery is due in December.

Duncan Geere is TechRadar's science writer. Every day he finds the most interesting science news and explains why you should care. You can read more of his stories here, and you can find him on Twitter under the handle @duncangeere.