It's all well and good carrying a rechargeable battery around with you, but they generally have quite limited capacity and can't charge your phone more than a couple of times. Aside from carrying a massive one, batteries really aren't the solution. But one company thinks fuel cells are.There's not much new about fuel cells. The idea has been around for some time, but no one has yet made them commercially available. Now Nectar has a working system that will go on sale this year.The key facts are that you'll get about 10 charges from this device. The fuel cell is replaceable and once it's discharged you recycle it, and buy another one. The device provides up to 2.5 Watts of power output, which means you can charge anything, from an iPad to your Android phone. Obviously, the number of charges will vary wildly.When asked about how safe the device was, we were told that it could survive in a car at temperatures of 60C, so there shouldn't be any cars exploding because someone has left a power cell on the seat. It's also safe enough to have been approved for use on aircraft.And because this is a fuel cell, it doesn't need to be charged first. So no waiting for hours for the battery to fill up, just plonk in a new cell, and away you go. We find this aspect especially pleasing, because we're forever forgetting to charge our external batteries.The good news is, Americans will be able to buy one this year. The bad news is, there are no plans to bring it to the UK until at least next year. The company told us that the main device will cost $299, with the disposable cells costing $10 each. Sharp maths minds will work out that means it's about $1 per charge.