The system, built by Exeter-based Agri-Energy, turns manure and food waste into heat and electricity and organic products. It also accepts grease waste, which it says is unique compared with other farm digestion systems in northern New England. The system could accept food waste from restaurants, hospitals and colleges. The farm is selling electricity generated to the grid and using excess heat for its buildings. It produces enough electricity to power 800 homes. There are only about a dozen large-scale digestion systems in the country.