Every year, Thames Water gets in touch about the giant fatbergs beneath Leicester Square. These are not pleasant. A fatberg is a sizeable accretion of congealed fat and cooking oil, liberally encrusted with human shit and anything else passing through the sewers.
These feculent mounds form all throughout the sewers, but are particularly common beneath the West End, with its high concentration of restaurants. The fatbergs are regularly chipped away by Thames Water flushers, lest the network become blocked. That's £1 million a month, literally down the drain.
But where there's muck there's brass. These noisome deposits will soon be put to better use, in a fat-fuelled power station at Beckton. The facility will, according to Thames Water, produce 130 Gigawatt hours a year of renewable electricity — enough to run 39,000 average-sized homes — though more than half the power will be channeled into running the Beckton sewerage works.
The plant will also take in oil from London's commercial kitchens and other sources of waste fat. It should be up and running by 2015. The Guardian goes into more depth.