CAMBRIDGE — Beneath a hot sun on a recent morning, a large garbage truck inched down Putnam Avenue, leaving a stench in its wake that lingered long after the orange compactor had disappeared down another street.
The pungent aroma came less from the truck than from the row of newly issued green bins lining the sidewalk, many of them containing a soupy residue of moldering food scraps.
“The heat isn’t helping the smell,” said Mia Counts, 26, a graduate student who winced as she walked past the open bins.
Still, Counts and many of her neighbors insist they’re willing to put up with the reek, for the good of the environment.
Last spring, Cambridge launched the state’s largest test of a citywide composting program, in which 25,000 households were provided kits to divert their food waste from the usual trash pickup headed for incinerators or landfills.
The program, which has already led to a sharp drop in the city’s waste stream, could be replicated in cities and towns across Massachusetts as the state reviews how it disposes of its waste, about a quarter of which is estimated to come from food scraps. The rotting remains, long a bane to landfills, also produce a significant amount of the state’s greenhouse gas emissions.
As scraps such as watermelon rinds and apple cores decay, they release methane, a potent greenhouse gas that traps at least 25 percent more heat in the atmosphere than carbon dioxide. Methane is responsible for about one-10th of all greenhouse gases produced in the United States, and about 14 percent of those emissions come from landfills, according to the Environmental Protection Agency. Composting food scraps allows the methane to be contained and used for heat and power.
Food waste also takes up precious landfill space, which has dwindled in recent years. In 2012, the state’s landfills had about 2.1 million tons of capacity; in 2022, environmental officials expect to have less than 700,000 tons of capacity, according to the state Department of Environmental Protection. Most of the rest of the waste is either burned in incinerators or exported to other states.
To prolong the life of landfills and reduce waste, the state has launched its own composting program. Large institutions such as universities, hospitals, and hotels that produce more than a ton of organic waste a week are now required to dispose of it by composting, donating what is edible to food pantries, or sending it to special plants that capture methane and convert the gas into energy, heat, or fertilizer.
But the state may not meet its goals.
In 2014, when the Patrick administration launched the program, environmental officials told the Globe they expected that year to divert 450,000 of the state’s 1.4 million tons of organic waste from landfills. But two years later, Massachusetts diverted only 260,000 tons, according to the most recent state figures from the Department of Environmental Protection.
The state has also fallen behind on efforts to reduce overall waste. In 2010, it set a goal of reducing the state’s total trash stream to 4.5 million tons a year by 2020. But the most recent figures from the state show that Massachusetts produced 5.6 million tons in 2016 — about 200,000 tons more than it disposed of in 2010.
Environmental officials nonetheless insist that the state remains on track to make substantial reductions to the waste stream. Since 2008, they noted, Massachusetts has eliminated nearly a million tons of waste, a 14 percent decline at the same time that the economy has grown by 14 percent. They also said they expect to achieve their goals of diverting 450,000 tons of food waste by the end of the decade.
“We look forward to working with local and legislative leaders to continue this progress,” said Joe Ferson, a spokesman for the Department of Environmental Protection.
Environmental advocates now are urging the state to commit to a new plan for the coming decade that would eliminate nearly all waste sent to landfills and incinerators, requiring a massive overhaul in the way the state manages its waste.
“We cannot recycle our way out of the disposal problems in Massachusetts,” said Janet Domenitz, executive director of the Massachusetts Public Interest Research Group, an advocacy group in Boston. “We need to turn the garbage truck around and commit to a goal of zero waste.”
Far from being eradicated, the state’s waste problems could worsen in the coming years as many municipal recycling programs are struggling.
This year, China and other countries began refusing to accept a large amount of recycled materials from the United States, saying that much of it is contaminated and creates pollution. As a result, recycling plants in Massachusetts and other states have been unable to sell much of the material they collect, hiking the costs of municipal recycling programs. Towns that used to earn money from their programs now pay as much as $70 a ton to have it hauled to landfills or incinerators.
Domenitz and others have called on officials to do more to curb the vast amount of trash that gets improperly disposed, such as batteries and tires; expand the state’s bottle law, so that millions of containers for noncarbonated beverages are eligible to be redeemed for a nickel; and impose a statewide ban on plastic bags, which often gum up the works at recycling plants.
They have also called on more municipalities to take the politically dicey step of requiring residents to pay fees based on the amount of trash they throw away. Fall River and Worcester have taken that step and have reduced their waste costs by millions of dollars over the years. In addition, advocates have urged the state to hire dedicated inspectors to monitor landfills, where an estimated 40 percent of the waste could be recycled.
“The state’s solid waste plan has been an absolute failure,” said Kirstie Pecci, director of the zero waste project at the Conservation Law Foundation in Boston.
One bright spot is that an increasing number of communities in Massachusetts have turned to composting. At least 27 municipalities now have drop-off programs; 10 have some kind of curbside collection program for food waste, state officials said.
In Manchester-by-the-Sea, which has been collecting food waste since 2014, town officials noted that food scraps are often the heaviest component of their trash, because of all the moisture. About a quarter of the residents take part in the town’s free composting program.
In Cambridge, the city this year spent $1 million to provide half of all households access to curbside composting. Each household received a small bin to collect food scraps in their kitchen, biodegradable bags to hold the waste, and special outdoor bins that lock to keep out rodents.
About 50 percent of those residents have been participating in the free program since it began in April, city officials said.
While they’re hoping more will start composting in the coming months, city officials say the program already has succeeded in diverting more than a million pounds of garbage from landfills or incinerators, reducing the city’s overall waste stream by 9 percent.
“That’s a huge reduction in our trash,” said Michael Orr, recycling director of Cambridge. “We haven’t seen anything like this before in our history.”
He estimates about 40 percent of the city’s trash can be composted. Some larger residential buildings still lack access to the program, but officials plan to extend it to those residents in the coming years.
The food waste is collected by city contractors at the same time as the trash and then taken to a plant in Charlestown, where it’s ground into slurry. From there, it’s shipped to a plant in North Andover, where it’s mixed with sewage and entered into special machines called anaerobic digesters, which convert the slurry into biogas and pellets for fertilizer. The biogas is used to generate heat, hot water, and electricity.
Some have criticized Cambridge for sending its material to a plant that mixes the food scraps with sewage, raising concerns that the fertilizer it produces could be contaminated with toxic chemicals.
Orr defended the city’s relationship with the plant, saying the pellets are safe and comply with state regulations.
Officials at the plant also defended their system. “The overall research suggests it’s a safe way of processing food waste,” said Cheri Cousens, executive director of the plant, run by the Greater Lawrence Sanitary District.
The more common concern about composting is the reek from the curbside bins, and their appeal to everything from rats to raccoons.
But Orr insisted the odor won’t be much of a problem after the summer, when cooler temperatures tamp down the stink that is a siren call to urban wildlife seeking a snack.
All in all, Orr said, the program is working as he had hoped. It’s just not big enough yet.
“We really just need more people to be participating,” he said. “Everybody should be doing this.”