It must be one of the worst jobs in utilities. Every day a special squad of “flushers” patrols London’s 109,000km of sewers, hacking at blockages to keep the system flowing.
And most of the 80,000 blockages each year are caused by cooking fats and oils, which congeal in the sewers and clump together, forming “fatbergs”. It costs Thames Water, the utility company in charge of much of London’s sewers, around £1m each month to clear, and it’s a horrible task.
“Trudging through the sewers where people have discarded cooking fat makes the job very messy and unpleasant,” says Martin Wall, a sewer flusher for Thames Water. “The fat mixes with sanitary items and wet wipes that also shouldn’t be down there, and sets hard. Fat is very difficult to remove, and the smell is disgusting.”
Congealed cooking fats and oils
But now Wall and his fellow flushers are due some relief from fatbergs thanks to an innovative scheme to capture London’s grease before it goes down the drain and burn it to generate electricity.
A new “green” utility company, 2OC, has signed a 20-year deal worth more than £200m with Thames Water to provide power and heat from a new combined heat and power plant. Burning fuels derived from fats, oils and greases which would otherwise be tipped down the drain or dumped in landfill, the plant will produce 130GWh of electricity a year, enough to power just under 40,000 average sized homes.
Thames Water will buy 75GWh of that to power its Beckton sewage treatment works, the biggest in the UK, and also a desalination plant. The rest of the power will be sold on to the National Grid.
A 2OC spokesman said that exactly how the fat will be collected from the city’s restaurants and homes is under discussion, and may involve third-party service providers.
Martin Wall is one of 39 “flushers”
Other fuel sources are likely to include oil wastes from food manufacturers, processors and animal fats. There will be no virgin oils from field or plantation grown crops.
A £70m contract to design and construct the new fat-burning plant has been awarded to London headquartered J Murphy & Sons, which will work with Jacobs Engineering. The plant, 2OC’s first power generating plant, is scheduled to start generating power in 2015.
Funding for the project is provided by a consortium of infrastructure investors iCON Infrastructure Partners II, alternative-investment fund managers EEA Holdings, and 2OC.
Commenting on the deals, Andrew Mercer, CEO of 2OC, said: “This is the culmination of many years of hard work from my world class team at 2OC. This is good for us, Thames Water and its customers and the environment. Renewable power and heat sourced in London, generated in London and used in London.”
For more international stories visit the CIOB’s global construction website GCR
