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Rubbish at huge incinerator site in south east London will soon be used to help heat thousands of homes.
Tonnes of waste is sent to the huge plant in Bexley from across London where it is burned and turned into electricity.
The excess heat generated during the process will be diverted to homes and businesses in London.
"This is something that I would argue we should already have been doing," said Ross Brown from waste management services company Cory.
"Leveraging this heat which is produced as a by-product from processing London and the South East's waste, this heat would otherwise have gone out into the air," he added.
The Government is putting £12 million towards the project making it the UK's largest planned heat network. Hot water will be sent by pipes, a process other cities have been doing for a while.
"London is more at the start of its journey but as we've seen from the network we have in Amsterdam which serves 177,000 customers it draws on heat sources from multiple areas," said Bindi Patel from European energy company Vattenfall.
In London the project could eventually be boosted with additional heat from Tube stations and factories to provide fossil fuel free heating in the capital.