When the Audet family turns on the lights at Blue Farm, they are using electricity that comes from cows-cow manure (粪肥), to be specific.
Cows produce a lot of wastes. One cow can create 30 gallons of wastes each day. Now imagine the output of over 1,000 cows at Blue Farm. That's really a big amount.
When farmers clean their barns, they put the wastes in a big heap, and spread some of them on their fields for fertilizer(肥料). But now places like Blue Spruce Farm have a new way of using cow wastes. They use them to produce electricity.