Surprisingly enough, no. You need to have power in your mobile telephone in order for it to work. Of course, given that my iPhone 5 barely survives an 8 hour day at work, that poses a problem (although, of course, the iPhone 5 does not support Apple Pay). This will, of course, be a particular issue on the tube. You swipe in, your battery dies, you can't swipe out. Could you use the original card to swipe out if you've got it on you, or do you just have to make do with a penalty fare? What about if you get checked on a bus- you'd normally tap your card on a reader, but if your phone's dead you could very well have paid but would appear to be a fare evader to the inspector?