|Will it really look like this?|
There has to be a catch, of course: if you're hiking along the Leeds-Liverpool canal and fancy a beer, the only source of water would be the canal itself, in which case I suggest you either carry a stomach pump or take a supply of fresh water with you, which rather negates the selling point of the product. And if you're hiking nowhere near water? Wait for rain, I suppose.
So what we are talking about is a sludge that resembles Marmite to which you add water, assuming you can find any, and then use a device to carbonate it and thus make it into beer; it sounds delicious. British microbreweries will be quaking in their boots.