Consolidated Edison Co. (Con Ed) again warned this week that if the Transcontinental Gas Pipe Line Co. LLC (Transco) Northeast Supply Enhancement project is not approved by New York regulators, it would likely have to suspend new gas service connections in the nation’s largest city.

The utility shares transmission infrastructure with National Grid that allows natural gas to reach customers in all of New York City’s boroughs. In a letter earlier this month to elected officials opposed to Transco’s expansion, Con Ed said “to the extent their project is not approved or built, it would impact our ability to purchase and, thus, deliver natural gas for our customers in New York City.”

The warning comes after Con Ed in January imposed a moratorium on new gas service in Westchester County to the north of the city, citing a lack of supplies to meet demand. National Grid has warned of similar measures in New York City if Northeast Supply isn’t built.

“National Grid has been clear about their potential inability to serve new gas customers absent new interstate pipeline infrastructure, and Con Edison shares those concerns about adequacy of natural gas supply coming into New York City,” wrote Con Ed’s Kyle Kimball, vice president of government affairs, in the letter. “To the extent we are not able to meet the demand needs of our customers for new or expanded natural gas service, we would have to move quickly to declare a moratorium on new gas connections in our New York City service area as well.”

Con Ed provides more than 1,700 new gas connections annually, Kimball said. However, if the utility expects to not be able to meet demand, the focus would shift to serving existing customers, which he said typically use the most gas on the coldest days of the year. Con Ed noted that the city’s energy grid is among the most complex in the world. Peak demand for the fuel was on especially sharp display early last year, when after a bitterly cold stretch of weather and amid blizzard conditions one of the highest spot prices ever recorded by NGI came in at $175/MMBtu in New York City.

While Kimball stressed in the letter that the utility is working to decrease demand for gas throughout its service territories with efficiency programs and new heating technologies, he said “residential and commercial customers will continue to choose natural gas for their heating and cooking needs.” He also said “natural gas has a role in the transition to a clean energy future.”

Another moratorium in the area, Con Ed officials said, would mean that residential and commercial developments, along with oil-to-gas conversions, new restaurants and renovations would have to find alternatives to gas to meet energy needs.

Anxiety at Con Ed about a lack of new pipeline infrastructure in the state, Kimball wrote, has been growing since 2016, when the New York State Department of Environmental Conservation (DEC) denied a water quality certification (WQC) for Constitution Pipeline, which would move additional gas supplies to the Downstate region.

DEC has since rejected the Northern Access expansion project and challenged other pipelines. It is currently reviewing Transco’s WQC application after a public comment period concluded last month. The agency suspended Northeast Supply’s regulatory process last year pending the Federal Energy Regulatory Commission’s environmental review, which was completed last month. DEC has said it expects to issue a decision about the by May 15, which is required before the expansion can move ahead.

What’s more, project opponents have said they would continue to challenge pending pipelines in the state despite recent victories for the projects at FERC and in the courts. The moratorium warnings also come at a time when the state is pursuing aggressive energy policies to curb the impacts of climate change.

At a hearing on Monday in New York City, Mayor Bill de Blasio’s administration reportedly warned that a gas moratorium would likely increase the city’s reliance on No. 4 fuel oil. Northeast Supply was proposed in part to help the city phase out the use of oil as it looks to curb emissions as well.

Northeast Supply would expand Transco to increase deliveries to National Grid, the largest distributor of natural gas in the Northeast. The project is designed to create 400 MMcf/d of incremental firm capacity to Northeast markets, primarily to feed demand for gas in New York City. Opponents have been particularly concerned about the roughly $1 billion project’s crossing of a bay between New Jersey and Queens.

So far, more than 60 federal officials have urged Gov. Andrew Cuomo to reject the pipeline, while a petition with 16,000 signatures and more than 250 groups in the state have emerged in opposition, according to

Con Ed’s gas service area in the New York City region includes parts of the Bronx, Manhattan, the northern half of Queens and Westchester County. It has about 1.1 million residential and commercial gas customers, including 232,000 in Westchester County.