The potato chip manufacturer said that the this initiative, coupled with the three wind turbines it installed at the Whittlesey factory in November 2007, will provide up to 70 per cent of the annual energy requirements required to operate its plant. The anaerobic lagoon digests the waste water from manufacturing process to produce a biogas, which is then stored and used to produce electricity through a gas burning generator. McCain said its investment in both projects has meant total annual generation from alternative energy on the site has the potential to reach 32,200MWh - the equivalent to powering over 7,500 domestic houses a year. Unused energy resoldThe processor claims that the wind turbines have reduced the plant's carbon dioxide emissions by 7,500 tonnes in the past six months and when the plant is not operating unused electricity is sold back to the National Grid. "We hope this demonstrates that a large scale manufacturing plant can operate efficiently while significantly reducing its carbon footprint," said CEO of McCain Foods, Nick Vermont. McCain Foods said that it is continuing to innovate and introduce new technology in all its UK facilities in a bid to limit the company's impact on the environment. Other initiatives The company said that, at its Scarborough site, it has invested in a heat recovery system that recovers waste heat from the cooking process and uses it to heat water used in the preparation process. The processor also said that it sources its potatoes as close to the factories as possible and is using solar panels on the refrigeration units of lorries to reduce the amount of fuel used. Food miles Most UK companies are now aware that consumers are increasingly worried about the affect that 'food miles', or the distance products and their ingredients travel before reaching the dinner plate. Increasing environmental awareness as well as growing individual consumer responsibility for taking care of the earth has led consumers to seek local ingredient sourcing. In response, UK manufacturer Boots is now selling a range of four sandwiches made primarily using ingredients from one UK county - Yorkshire. UK crisp manufacturer Walkers claims to now make all of its crisps for the UK market with '100 per cent British potatoes', in an attempt to reduce the carbon footprint of the well-known snacks. Carbon TrustBoth Walkers and Boots are members of the Carbon Trust, a private UK company set up by the government to develop policies addressing climate change such as food miles. The two companies were also the first in the country to sign up to the Carbon Trust's 'carbon reduction label' scheme last year, which requires companies to communicate the embodied emissions of a product on its packaging. For example, Walker's state that 75g of greenhouse gases are given off in the production of a 33.5g pack of cheese and onion crisps. This total takes into account the energy used in the farming, manufacturing and packaging, as well as the petrol needed to distribute the snack across the country. Several other food manufacturers, including Cadbury, Coca-Cola and Muller Dairy, have also promised to measure all the carbon emitted in making some of their key products. Tom Delay, chef executive of the Carbon Trust, said in September that the willingness of UK processors to measure carbon emissions marks "a key stage in the development of a country-wide standard."