The Epiphany One Puck may well be the world's most awesome coaster. It may also be the most useful. The One Puck doesn't just protect your coffee table from drink sweat, it also charges up your smartphone.
You don't have to plug the Puck into an outlet. It uses a small Stirling engine to provide the power. The device has two sides, one red and one blue. Place a hot drink on the red side, or a cold drink on the blue side.
Stirling engines have been around since the 1800s. They work by turning heat disparities into energy. Epiphany Labs has built a working prototype of its One Puck, though the company is still vague on just how long it takes for the device to charge up a phone. There are a lot of variables at play, including how hot or cold the source is.
Any source of heat that can fit on the Puck will work, though I don't know how much energy a warm cat would produce. It works best with something that's very warm (like a steaming cup of tea) or very cold (like a frosty brewski).
Epiphany is aiming to raise $100,000 on Kickstarter to turn the prototype into a gadget that can be mass-manufactured. As development continues, hopefully we'll get more details on how the Stirling engine technology has been adapted and how long it will take to charge devices. The expected delivery date for the pledge Pucks isn't until March of 2014.
Early birds can still get in on a $99 pledge price. The regular pledge for a Puck is $115. It's not as slim as most phone chargers, but it is portable enough to throw into a purse or briefcase for those times when an electrical outlet isn't convenient, but an ice cold lager is.