You can now use your laptop for an unlimited amount of time, even if you’re miles away from an electricity plug. According to this article from Nature, a Californian start-up company, UltraCell Corporation, has developed a new fuel cell system for portable devices.

This device, which is about the size of a paperback novel, delivers 25 watts of continuous power and weighs only 40 ounces — about one kilogram. The only drawback is its price, currently in the tens of thousands of dollars. But this system was designed according to specifications from the U.S. Army, which might remain the only customer until prices get down to a few hundred bucks in about two years. Read more for other details about this attractive new device.