The chain's food waste will be converted into biogas for renewable energy generation at Shanks' 60 ktpa anaerobic digestion plant in Cumbernauld, Glasgow, which it operates as a joint venture with Energen Biogas.
Under the power purchase agreement, M&S will buy around 19,000 MWh of electricity a year from the plant, which is enough to power 33 of its Simply Food stores.
M&S says the deal will help 'close the loop' on its food waste and is an integral part of its Plan A sustainability initiative.
"Having advocated the use of anaerobic digestion technology since the launch of our sustainability programme, Plan A, back in 2007, we're now seeing in practice how the plant at Cumbernauld is helping M&S to maintain two of our targets: to procure 100% renewable electricity and send zero waste to landfill," says Giacinto Patellaro, head of energy supply and risk for the chain.
Shanks already has a similar deal in place with Albert Heijn, the leading supermarket in the Netherlands, treating the chain's organic waste at its Greenmills plant near Amsterdam, which is the largest of its type in Europe.
"M&S is a pioneer in responsible business practices and we are delighted to enter into this agreement with them," says Shanks' UK managing director Ian Goodfellow. "Not only does this reinforce our strategy to make more from waste, it also reflects Shanks' strong and growing presence in organics recycling and recovery."
As well as the Cumbernauld plant, Shanks is also building a 48 ktpa anaerobic digestion plant in Bicester, Oxfordshire and has plans for a larger 90 ktpa plant in Pontypool in South Wales.