NYC Biogas Innovation Becomes Moneymaker

NYC Biogas Innovation Becomes Moneymaker
The Newtown Creek Wastewater Treatment Plant serving New York City in Brooklyn, produces three million cubic feet of digester biogas a day, but uses only half of it.

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It’s a case of triple serendipity. The Newtown Creek Wastewater Treatment Plant serving New York City in Brooklyn, produces three million cubic feet of digester biogas a day, but uses only half of it. The transmission company National Grid is looking for more natural gas to provide to its customers. The New York City school system produces about 1.5 tons of food scraps each week from its school breakfast and lunch programs, sending the garbage to landfills. 

Like a triple play around the Mets infield, all three issues will be dealt with in an imaginative project that will start up later this year. 

Treatment Plant Superintendent Jim Pynn is ready to describe the project to any audience he can find.

“The Newtown Creek facility is designed for a dry-weather flow of 310 mgd. We have eight egg-shaped digesters, and we produce about 150,000 cubic feet of waste activated sludge a day,” he explains, ticking off the numbers like a statistician. “We get 18 cubic feet of methane per pound of volatile solids destroyed. That’s 500 million cubic feet a year.” 

About half the quantity is used to fuel Cleaver-Brooks boilers that heat the plant’s buildings, power the air conditioning system in the summer, and keep the digesters at 98 degrees Fahrenheit. 

“But now we’re not going to flare the rest of it anymore, we’re going to sell it,” Pynn says. 

That’s because National Grid, which provides natural gas and electricity along the East Coast including the New York area, has formed a partnership with the city’s Department of Environmental Protection. In an agreement facilitated by the city’s Office of Sustainability, the company will purchase the extra biogas, use a refrigeration process to scrub out the CO2, and transmit the remaining high-quality natural gas to customers. The amount will supply the heating needs of about 5,000 homes. 

Not only will National Grid purchase the biogas, the company will also fund the infrastructure necessary to clean up the gas and get it to customers. “We already have a pipeline connecting the plant to National Grid,” Pynn explains. He says the existing pipeline will be equipped with a metering station and used to transmit the biogas to the company. 

“National Grid will build the infrastructure and maintain it. Our operators will be able to monitor the system and will be alerted to any alarms. There will be no disruption to our plant operations at all.” 

While this is a good story so far, there’s more. 

Pynn switches the discussion to New York City’s schools, where most students eat breakfast and lunch and produce a significant amount of food scraps in the process — 1,400 schools, 1 million students. “Hundreds of tons of food waste a day,” he says. 

Working with Waste Management, the city plans to send the garbage to a processing plant in Brooklyn where magnets will remove any metals and macerators will grind up the material so it can be made into a 15 percent solids slurry. Then, tanker trucks will haul the slurry to the Newtown Creek plant where one of the eight digesters will be reserved for the food waste. 

“The stuff is the consistency of oatmeal,” Pynn says. “We’ll start with three 5,500-gallon tankers a week. We’ll get the same gas yield of 18 cubic feet per pound of volatile solids destroyed. 

“This program can produce 250 to 500 tons a day of food waste slurry, enough to blend with the waste activated sludge in all our digesters. That should produce enough gas to serve 50 percent more homes in the area.” 

Pynn expects construction of the new biogas infrastructure to commence late this spring and be ready to roll by late 2014. “We just signed off on the design last December,” he says. 

He points out that the city and National Grid will share in capital costs (about $5 million) and once that is recovered, will also share in the revenue from the sale of the gas. 

Is this a unique project, given that the wastewater industry is returning to biogas as a fuel source around the nation? Pynn says he’s not certain, but he hasn’t heard of any quite like it anywhere. Triple plays don’t happen every day.



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