The boiler will run on wheat feed, a by-product of flour production, and will ensure 70% of the energy used at the site is from renewable sources.

Tate & Lyle said its new energy source would be running at its east London refinery in two years.

The site is already a net exporter of energy to the grid, the company said, and the scheme will ensure it is green.

Ian Bacon, chief executive of Tate & Lyle Sugars, said: "We believe the boiler being constructed at our Thames site is not only the largest of its kind for London, but also a first for the UK food and drink industry."

The boiler, which will run 24 hours a day, seven days a week, will have a 65MW capacity and will cut the carbon footprint of sugar to 0.32 tonnes of CO2 per one tonne of sugar, Tate & Lyle said.

It will power the combined heat and power plant for the factory, which is one of the largest cane refineries in the world, processing 1.1m tonnes of sugar a year.