As part of its pledge to go green, Marks & Spencer (M&S) are using food waste to power some of its stores. The announcement comes when the retail giant has just declared that it will be charging 5 pence for its plastic bags. Two anaerobic digesters will be providing renewable electricity to M&S stores. One is located in Shropshire and takes municipal food waste and the other will be located in Somerset and will take cow flurry and grass cuttings. An M&S spokeswoman said: The anaerobic digesters produce gas that is converted into electricity. The energy is then fed into the national grid and in total we have enough energy from these plants to power six M&S simply food stores. Once the renewable electricity goes to the national grid, the store then buys the amount of green energy that it has contracted with its supplier. Chief executive Stuart Rose said: Plan A is driving change and innovation right across M&S. We are the first retailer to use food waste to power some of our stores. We know there is still much to do and have complicated issues to tackle, but we are continuing to make strong progress. M&S are working closely with two anaerobic digestion companies in Shropshire; Greenfinch and Biocycle. The anaerobic digester based in Somerset will open in spring 2008. This is all part of the plan A and we are working with other food suppliers and M&S suppliers encouraging them to look at anaerobic digestion and to diversify their businesses. It is a good way of reducing our environmental impact through managing waste, said the spokeswoman.