News Feature | November 16, 2015

New York City Strives For Net-Zero Energy At 14 WWTPs

By Laura Martin

“Net-zero energy” may sound like nothing more than an idealist turn of phrase, but one city has a plan to make it a reality at its 14 wastewater treatment plants.

As part of a sustainability initiative known as OneNYC, the city of New York is undergoing and planning extensive upgrades to achieve net-zero energy at its wastewater treatment plants by 2050, reports TriplePundit, a media platform focused on sustainability in business.

The city wastewater system currently treats 1.3 billion gallons of wastewater daily, accounting for a large amount of energy consumption.

On New York’s city government website, the plan for achieving net-zero in described in detail:

“Improving the efficiency of wastewater treatment, increasing the production of biogas, and capturing and beneficially using all biogas as a renewable energy source will significantly reduce carbon emissions associated with flaring, as well as offset emissions from energy generated from traditional fossil-fuel sources. Over the next decade, the City will achieve further reductions in energy consumption across all of the wastewater treatment plants by decreasing demand, increasing on-site power generation, recovering and reusing biogas, and undertaking co-digestion of organic wastes.”

As part of this initiative, the city recently announced a $30 million investment for upgrades of the Port Richmond Wastewater Treatment Plant on Staten Island.

The upgrades will include three new boilers, a new exhaust capture system and one of the largest rooftop solar arrays in the city, which will generate approximately 1.6 million kilowatt hours and will supply as much as 10 percent of the plant’s power needs, according to a press release released by the city. All together the upgrades will reduce greenhouse gas emissions from plant operations by more than 28,000 metric tons.

The new boilers use a combination of biogas and natural gas and replace equipment dating to the 1970’s that ran on heating oil alone.

“Using the byproducts of wastewater treatment to provide energy to fuel the same plant, and shave off even more of the energy load with a sizable solar array, makes a significant contribution to NYC's air quality as well as reduces energy and cost over the long run, while bringing down greenhouse gas emissions,” said Nilda Mesa, Director of the Mayor’s Office of Sustainability, according to the release.

Cogeneration is also be utilized to improve energy efficacy at several New York City wastewater plants.

A 12-megawatt cogeneration system at is being installed at the North River Wastewater Treatment Plant, according to an outline on the New York City’s government website.  This system will use digester gas, produced on site, as well as supplemental natural gas to generate electricity that will meet the plant’s base electrical demand and recover enough heat for the plant’s heating needs. This project will offset the use of 90 percent of utility electricity and over 1.7 million gallons of fuel oil and double the amount of digester gas used.  Similar systems are being considered at the Wards Island Wastewater Treatment Plant and the Hunts Point Wastewater Treatment Plant in the city.