Bubbling black liquid churns inside 145-foot-high tanks at the Newtown Creek sewage-treatment plant in Brooklyn. Like robotic stomachs, they burp methane, a byproduct of processed organic waste.
New York Mayor Bill de Blasio says gas produced at the facility could heat more than 5,200 homes. To achieve that goal, he’s asking 100,000 households to separate food scraps from other garbage and leave them in city-issued plastic bins for curbside pickup. The food would be hauled to Newtown Creek’s egg-shaped tanks and mixed with sewage to create natural gas.
“We are trying to figure out how to market our waste as a resource,” said Sanitation Commissioner Kathryn Garcia, whom de Blasio appointed in March to run the 9,500-employee department. “If we are successful here, nationally and internationally you will see this program implemented.”
New York is trying to reduce the $350 million it spends each year -- and the environmental impact of -- hauling trash to landfills as far away as South Carolina. Discarded food makes up about 18 percent of its 10,800-ton-a-day residential trash, and city officials say the organic waste can be converted into fuel and compost. If the voluntary system works, it will be rolled out to cover all 8.3 million residents and may become mandatory.
Such lofty goals won’t be easy to achieve in the most populous U.S. city, which issued more than 51,000 violations in fiscal year 2013 for its mandatory metal, glass, plastic and paper program. Most apartment buildings were built before architects designed space for recycled refuse, Garcia said.
The city’s recycling participation rate has been stuck at 43 percent or less for years. Only about 15 percent of its trash gets diverted from landfills, well below a goal of 75 percent by 2030. A ban on throwing away electronic devices takes effect next year, and a city law requires the diversion rate to reach 25 percent by 2020.
In San Francisco, a private trash-hauling utility charges residents and businesses by how much landfill-destined refuse they generate. The city boasts a diversion rate of 80 percent, though it uses a different calculation than New York. Seattle reports a 60 percent rate. In Boston, it’s 20 percent.
New York’s food-scrap experiment started under former Mayor Michael Bloomberg in 2012 with 30,000 homes and 15 schools. This year, it will cover 240,000 residents and more than 400 schools. Bloomberg, appointed in January as United Nations special envoy for cities and climate change by Secretary-General Ban Ki-moon, is the founder and majority owner of Bloomberg News parent Bloomberg LP.
Engineers have discovered that methane production is enhanced when food is mixed with sewage and bacteria in egg-shaped, oxygen-deprived tanks at the human-body temperature of 98 degrees Fahrenheit (36.7 degrees Celsius). New York’s pilot project, which began with about two tons of processed scraps a day, now will ramp up to 50 tons, escalating to 250 tons by the end of 2015.
Newtown Creek’s eight 44-meter-high tanks have the potential to hold 500 tons of food for the 15-day process. Thirteen other city plants could be upgraded to handle an additional 500 tons, said Vincent Sapienza, deputy commissioner for waste water at the city Environmental Protection Department, which operates the Newtown Creek plant.
“We have to be careful to not to overfeed our anaerobic digesters because, just like a human stomach, they can get upset and the sludge can turn acidic,” Sapienza said. “But we have the capacity to take about 30 percent of the food scraps now destined for landfills and turn it into natural gas to heat homes.”
The methane will be pumped into pipelines connecting the city’s plant with a new refinery being built next door by London-based National Grid Plc, which supplies Brooklyn with natural gas to heat homes and businesses. The city will donate the methane to National Grid, which will pay for refining and distribution. If the market price of the gas ever exceeds National Grid’s cost to process and deliver it, the company will compensate the city for the methane it uses, Sapienza said.
Officials say the expense of diverting garbage from landfills will be less than the average $93 a ton it now pays to dump. The city spends $74 a ton to send its recycled metal, glass and plastic to a Sunset Park, Brooklyn, processing plant operated by a U.S. unit of Sims Metal Management Ltd., an Australian-based company with 270 facilities on five continents.
Recycled paper nets the city about $3.3 million a year, or about $10 a ton, and the Sanitation Department receives about $10 per cubic yard when it sells compost to landscapers.
“The good news is there’s a lot more to be captured, a huge potential for growth,” said Tom Outerbridge, a spokesman for Sims. “The bad news is the city has had mandatory curbside recycling in place since 1989, and that capture rate has been stubbornly stuck,” so “the challenge is whether it’s education or enforcement to get this material out of the garbage stream and into recycling.”
Worldwide, the market for municipal waste, from collection to recycling, is valued at an estimated $410 billion a year, yet only about a quarter of the 4 billion tons of garbage in cities is recycled or recovered, the UN reported in October.
Paris Mayor Anne Hidalgo, on a May 30 visit to New York’s City Hall, described garbage disposal as a “difficult problem affecting all large cities.” The French capital is experimenting with 80 restaurants that have volunteered to separate food scraps from trash to be fed into methane-creating treatment tanks, she said.
“We are constantly looking to our peers across the country and around the world,” Garcia said.
One New Yorker who wants the plan to succeed stood outside his home on 13th Street in Park Slope, Brooklyn, last month, near the bin where he stows his food waste. Pete Herman, a 49-year-old independent rock musician, said the city made it easy for him “to assume responsibility and recycle food scraps instead of just putting it in my garbage.” The brown plastic bin seals tightly, keeping rodents out and odors in, he said.
“I never realized how much food I threw away,” he said. “For the last two weeks I haven’t needed to set out my regular trash can for collection by the garbage truck.”