Fat, oil and build-ups in drains will soon be powering what will be the world's biggest fat-fuelled power station in Britain.
The grease will be fed into the power station at Beckton in East London, and is set to produce 130 Gigawatt hours (GWh) a year of renewable electricity - enough to run 39,000 average-sized homes, according to Thames Water.
The water company has agreed to buy 75 GWh of this output to run Beckton sewage works, which serves 3.5 million people, and the nearby desalination plant, which is operated in times of drought or other emergencies.
The remaining power will be sold on to the national energy supply grid.
The plant is developed and run by 2OC and financed by a consortium led by iCON Infrastructure.
Thames Water has also committed to provide at least half of the fuel the generator requires to run - in the form of 30 tonnes a day of fat, oil and grease - enough to fill a six metre-long shipping container - that would otherwise clog up London's sewers.
Leftover, low-grade cooking oil and food fat will be collected from food outlets and manufacturers.
Solidified grease, such as from lamb and chicken, will be harvested from 'fat traps' in restaurant kitchens and from pinch-points around the capital's sewer network.
The rest of the power plant's fuel will come from waste vegetable oils and tallow (animal fat).
Andrew Mercer, chief executive of 2OC, said: "This is good for us, the environment, Thames Water and its customers.
"Our renewable power and heat from waste oils and fats is fully sustainable. When Thames doesn't need our output, it will be made available to the grid meaning that power will be sourced, generated and used in London by Londoners."
Piers Clark, commercial director for Thames Water, said: "This project is a win-win: renewable power, hedged from the price fluctuations of the non-renewable mainstream power markets, and helping tackle the ongoing operational problem of 'fatbergs' in sewers."
London-based J Murphy and Sons have won the contract to build the plant, which is due to be operational in the first quarter of 2015.
Every year across its 109,000km of sewers, Thames Water removes 80,000 blockages, half of which are caused by fat wrongly poured down drains.
Clearing these blockages costs the firm £1 million a month.
The power the water company has committed to buy accounts for 6 per cent of the 1.2 Terrawatt hours of power a year it requires to run its water and waste water networks serving 14 million people across London and the Thames Valley.