stores have sent this facility all the food they can’t sell or donate. © FEED Resource Recovery, Inc.

I n 2010 an estimated 31 % of the food in U.S. stores and homes went uneaten, and Americans shipped approximately 34 million tons of food waste to landfills.1 When food decomposes under anaerobic conditions—for instance, buried beneath other waste in a landfill—it produces methane, a highly potent greenhouse gas.1 According to the U.S. Environmental Protection Agency, landfills are the third largest producer of methane in the United States, accounting for about 18 % of methane emissions in 2013.2 In recent years U.S. policy makers have begun to take action to reduce the flow of food into landfills, in part to stem greenhouse gas emissions but also to save businesses the cost of disposal. In 2011 Connecticut became the first state to initiate such action, prohibiting the landfilling of food waste by entities that generate at least two tons per week and are located within 20 miles of a food-recycling facility.3 In 2012 Vermont initiated a ban similar to Connecticut’s but included a phase-in schedule in which smaller waste generators will face bans in coming years.3 In October 2014 Massachusetts launched the toughest, most ambitious such plan in the country by banning the landfilling of food waste by all entities that produce at least one ton of food waste per week.4 And as of 1 January 2015, Seattle requires that food waste make up no more than 10 % by volume of any resident’s or business’s trash.5 But if food is banned from landfills, where can it go? The primary options have been to give unsold food to food pantries or ship it to composting facilities. But recently anaerobic digestion has been drawing attention as a method that can not only accomplish greenhouse gas reduction but also use the food waste as an energy source