This is really a strange thing New Scientist puts. Making electricity from sewage. The waste of our eating is possible to use as power. Truly a new definition of "dirty electricity" (organic fuel as oil and coal is often called it).
Since NS often use a language that goes over my head I can't really explain the technic but it's useful since we all have to go to the loo.
But it won't be in the near future: "One way to think of this technology is that it is currently at the state of development that solar power was 20 to 30 years ago - the principle has been shown, but there is a lot of work to do before this is widely used."´.