Clean Connection Generators Help Improve City Air Quality

The Vernon Boulevard Power Now! site in Queens (foreground)

Forecasts of tight electricity supplies in New York City this summer underscore the continued importance of small, clean power plants that the Power Authority installed in 2001 at six locations in the city to help meet that summer's peak power demand.

Since then, the new generating facilities, fueled by natural gas, have proved to be indispensable for keeping the lights on, and air-conditioners humming, in heavy-use periods. While the plants, which together can generate about 400,000 kilowatts, have played a critical role in maintaining the reliability of the city's electricity system, an important bonus has been their impact in protecting the environment. (NYPA also installed a similar facility in Suffolk County to help provide clean power for Long Island.)

How can power plants, no matter how clean and efficient, be an environmental boon? As with real estate, it all comes down to location.

Because transmission constraints severely limit New York City's ability to import power, reliability rules call for enough in-city generating capacity to meet at least 80 percent of peak requirements.

Older plants, which burn oil and natural gas, are not as clean as the new NYPA generators. The new plants permit operators to reduce the output from the older facilities, thus improving air quality.

The NYPA plants' environmental benefits were highlighted in the Power Alert III report, issued in May by the New York Independent System Operator (NYISO), which operates the state's transmission system and wholesale electric markets. "The siting of new electric generation, as is proposed in this report, will improve New York's air quality," the NYISO said. "This has been demonstrated by the small, clean power plants that the New York Power Authority installed in six locations in New York City in 2001."

The Power Authority has dubbed the small plants its Clean Connection, because they're located in areas of the city where transmission congestion makes local power production essential.

"New York City is considered a 'load pocket,' which means it can't receive enough power from sources outside the city for its full electric requirements," said President and Chief Executive Officer Gene Zeltmann. "Since the overwhelming percentage of its power has to be provided from within its own borders, the small, clean generating plants have had a marked impact in improving air quality."

He noted that the Power Authority spent nearly $77 million to equip the New York City plants with the most advanced technologies for limiting emissions. But to truly grasp their environmental benefits, it is necessary to compare their emissions rate with those of the older plants-large and small-that operate in the city.

According to federal data, during 2002 the new NYPA plants emitted less than one-tenth of a pound of nitrogen oxide (NOx), a major source of smog and a greenhouse gas, for every megawatt-hour (mwh) of electricity they produced. In contrast, federal and state figures show that older, inefficient plants of comparable size in the city put out an average of 8.6 pounds of NOx per mwh. That meant nearly a 99 percent cut in emissions per mwh from operation of the Power Authority facilities.

Federal records show that even relatively efficient larger power plants in the city produced an average of about 1.8 pounds of NOx per mwh. That translated into a 94 percent reduction in emissions per mwh.

For sulfur dioxide (SO2), the impact of the small NYPA plants has been even greater. Fueled solely by natural gas, they give off virtually no SO2, a pollutant that contributes to acid rain. By contrast, power plants in the city that burn oil at least some of the time release SO2 to the air.

The improvements in air quality from NYPA's new plants promise to be further enhanced by the Authority's efforts to offset even their limited emissions. These measures include installation of eight fuel cells, soon to go in service, that will harness waste gas from sewage treatment facilities to produce clean electricity; plans to retrofit 1,000 diesel school buses in the city with the latest pollution controls; and various other efforts, from helping to put zero-emission electric vehicles on the road to installing high-efficiency lighting.

These initiatives will build on NYPA's extensive programs to save energy and protect the environment in New York City and throughout the state.

The NYISO has predicted that the city's power supply will be stretched to the limits this summer. So it's likely that NYPA's small plants will be called on again to help stave off shortages. And—as they do throughout the year—they'll continue to pay big environmental dividends as well.

By Mike Saltzman
July 2003