If your smartphone dips into the red while you're out of the house, why scrabble for a portable battery when you can recharge with hydrogen? That's the sales pitch being made for the Upp, anyway. Intelligent Energy's first fuel cell charger is now available in Apple Stores across the UK, as well as on the Upp website. It gives power-hungry gadget fans a cleaner way to keep their devices topped up, but inevitably, there are some caveats. For one, the Upp charger will set you back a whopping £149, an amount that far exceeds the asking price for a handful of portable batteries. For another, the device is a little large and cumbersome; this isn't something you can just slide into a handbag or jacket pocket.