The multi-million pound plant is already at an advanced stage of construction and will be commissioned this year.
BiogenGreenfinch’s Anaerobic Digestion (AD) process uses bacteria in a sealed chamber to break down food waste, producing a methane-rich biogas and a nutrient-rich bio-fertiliser.
The investment from the food retailer is the first step of a planned joint venture between the two companies, which will include a review of other opportunities between them in the UK.
It follows a current initiative run in conjunction with 38 local Sainsbury’s stores linked to its Northampton Distribution Centre.
John Ibbett, chairman BiogenGreenfinch, said: ‘The Westwood site will not only dispose constructively of Sainsbury’s own waste, but will also be available to get rid of that produced by its suppliers, producing electricity for thousands of people and in turn, fertiliser for use on growing crops.’