Not Your Grandma’s Compost In-vessel Composting Offers Great Green Promise

Nicholas J. Smith-Sebasto loves showing off his “silky, gorgeous compost.” Only, Smith-Sebasto isn’t your typical gardener with a bin full of old leaves and watermelon rinds. From 2007 to 2009, the environmental science professor operated one of the country’s few university-based, aerobic, in-vessel composting systems. Since starting a new job as executive director of the School of Environmental and Life Sciences at New Jersey’s Kean University this fall, he’s been developing an even more advanced system.

While Smith-Sebasto was a professor at Montclair State University, he diverted 60,000 pounds of the college’s food waste from landfills. The scraps were mixed with wood chips (to extract moisture and provide carbon) donated from a local cabinetmaker. The unit slowly rotates and heats the material to 135 degrees. It can process about 500 pounds of food residue a day, for less than $2 in electricity.

“Composting food and organic waste really epitomizes recycling,” says Smith-Sebasto. “In a sense, recycling plastic bottles isn’t really recycling, because it can only be done a few times. That’s not the case with organic materials.”

If all of the food waste generated each year in the U.S. were composted instead of landfilled, the resultant reduction in carbon dioxide (CO2) emissions would be equal to taking 6 million cars off the road, he says. Plus, when organic waste is dumped in a landfill, it breaks down slowly through anaerobic decay. That releases methane, which is 25 times more potent than CO2.

“Silky” compost © CUNY Institute for Sustainable Cities

An estimated 40% to 50% of all the edible food we grow is wasted, according to a decade-long study by Timothy Jones of the University of Arizona. At home, the average family throws away 14% of their food purchases, or $590 a year. That’s $43 billion worth of wasted food overall.

New York City’s Lower East Side Ecology Center is doing its part to reverse the trend with educational workshops for do-it-yourselfers and an in-vessel compost system the group has maintained since 1998. According to compost program manager Carey Pulverman, about a thousand city families drop off their table scraps. “But this is a city of eight million,” she says, “and we haven’t come near mainstream penetration.”

Pulverman tries to educate the public with samples of rich compost and a plastic worm. “I show people that it’s not scary or gross,” she says.

Farmers’ markets, she notes, would be natural settings for collecting waste and redistributing compost. Some cities, including San Francisco and Seattle, already have home pick-up of food waste, although the idea is taking time to gain traction. Critics worry about hygiene and the “ick” factor. But these issues have been largely overcome in Europe, where composting is much more common (thanks in part to high landfill fees).

Innovative in-vessel composter. © Nicholas J. Smith-Sebasto

In-vessel composting dispenses with many common problems. The method keeps pests out and smells in. As a result, Smith-Sebasto sees no problem including meat, dairy and oils in the composter. In-vessel systems are also space saving, making them ideal for Manhattan parks or adjacent to university cafeterias. Smith-Sebasto’s first unit is only 30 feet long, and he says his new system will be able to handle nearly twice as much volume at roughly the same size. This means waste can be processed where it is generated, reducing transportation and emissions.

About 70,000 tons of food and 300,000 tons of yard waste is composted for Seattle each year by Cedar Grove Composting. The company’s technology can process 40,000 tons on just 2.5 acres.

There is a drawback to in-vessel composting: Initial costs run to tens of thousands of dollars. The system at Montclair State was set up with a grant. Still, according to BioCycle magazine, large-scale food composting projects nearly doubled between 2000 and 2007, from 138 to 267.

The U.S. already pays $1 billion a year to deal with food waste. What if that revenue could be used for smarter composting, creating green jobs in the process? Once running, Smith-Sebasto’s system processes waste at a rate per ton as low as $1, much lower than even the cheapest landfill tipping fees in the Heartland.

Smith-Sebasto envisions in-vessel composters for schools, industrial parks, hospitals, grocery stores and anywhere else large numbers of people gather. “The fact that we even tolerate the word “waste” as a noun shows how far we are from sustainability,” he says.