The facility at Cattlegate Farm, Enfield, will generate renewable energy for the grid from the vast amounts of food waste produced daily by London households, restaurants and the food industry.
The nutrients in the waste will then be recycled by the facility to make agricultural fertilizer.
Under the contract, Xergi will build the plant and be responsible for the commissioning and operation for two years.
In order to operate the plant, Xergi will establish a new organization.
In addition to featuring a pre-treatment facility that sorts plastic residues from organic waste, the plant will comprise an engine plant capable of producing 1.5MW of energy, enough to power about 1,750 households.
The plant construction, which commenced in August 2014, is planned for completion in May 2016.
Xergi CEO Jørgen Ballermann said: "We are proud that we now have the opportunity to help make London’s food and energy production greener. Our technology is particularly suited to this task and we therefore look forward both to building the plant and the responsibility for operations."
Willen Biogas is owned by the investment funds Foresight Environmental Fund (FEF) and UK Waste Resources and Energy Investments fund (UKWREI).
