Mass General Composting Program Turns Food Waste into Energy

Ever wonder what happens to food remnants once a dining tray is placed on the conveyor belt and disappears into the kitchen at Massachusetts General Hospital's Eat Street Café? Those leftovers become fertilizer, electricity and heat thanks to a partnership with Agri-Cycle Energy, a Maine-based company that helps turn these scraps into clean, green energy.

In 2020, Mass General composted 523 tons of organic waste from its cafeterias, bringing its total to 2,836 tons since it first partnered with Agri-Cycle Energy in 2014. Last year’s amount alone is estimated to have reduced greenhouse gas emissions equal to 787 barrels of oil—or the electricity used to power 50 residential homes for one year. And, from Mass General's total waste mixture over six years, the farm has been able to offset more than 10,000 vehicles, create 71,600 gallons of natural liquid fertilizer and produce 180 yards of compost.

“We are very proud of this initiative,” says Latoya Brewster, director of Mass General's Environmental Services. “As a health care organization dedicated to being as sustainable as possible, we are thrilled that we can make sure our food waste is put to better use.”

Six days a week, Agri-Cycle picks up the remains from Mass General and brings them to be mixed in a local anaerobic digester. The system converts this food waste into an organic slurry product that is used to generate renewable green energy.

“According to the National Institutes of Health, up to 40% of food produced in the U.S. is wasted each year, and the majority winds up in landfills,” says Greg Williams, director of Waste Solutions at Agri-Cycle. “When food decomposes in a landfill it produces methane, which is approximately 20 times more potent in trapping heat than carbon dioxide.”

At Mass General, staff and visitors sometimes ask why there are no trash and recycle bins available in the Eat Street Café. Brewster says, “The work is all done behind-the-scenes. Staff sort the compostable food and separate out the recycling to make sure the hospital is most effectively disposing of the waste to ensure we are being as sustainable as possible.”

What happens to the waste? View this Agri-Cycle PDF to learn more about anaerobic digestion.