MTA Hopes to Cool Off Subway Platforms With Thermal Tech

Public officials are looking into whether extreme heat could one day be eliminated from New York City’s subway system, by redirecting it away from station platforms via something known as a thermal energy network.

Specifically, an $800,000 feasibility study is being conducted at the interconnected Chambers Street and Brooklyn-Bridge City Hall stations in Lower Manhattan, with the hope of channeling any captured excess heat upwards towards municipal buildings during the winter. In addition to cooling off passengers at the station, such a system would save energy, according to city officials.

Mayor Zohran Mamdani and NYC Comptroller Mark Levine joined MTA Chairman Janno Lieber to hype the possibility of such an energy system at an Aug. 10 press conference at the subway station in question.

“I don’t have to tell any New Yorker that it is brutal underground in the summertime,” Lieber said, singling out the City Hall subway stop as an “especially” stark example of such temperatures.

“Bringing down temperature is a really complex challenge in a system where the stations are 100 years old and they have open entrances, stairways, vents,” Lieber added. “As I always say, the subway is not a submarine, it is not a closed environment.”

Mayor Mamdani noted that the “thermal network energy feasibility study will explore the possibility” of heating multiple municipal buildings situated above the Brooklyn Bridge-City Hall stop, including the David Dinkins Building and City Hall, during winter months.

“To do so, we would capture heat in boreholes that would run 500 to 600 feet underground,” Mamdani said, which would then be transported through “a system of circulating pumps and pipes...to warm the offices where our municipal workers are hard at work, powering this incredible city.”

“This would be the first thermal energy system of its kind in any American transit system,” he added. Indeed, Mamdani pointed out that old blueprints for the station included cooling fans connected to groundwater pumps, which the newly-proposed thermal energy study—while different in some respects—is taking inspiration from.

Comptroller Levine, who spoke next, compared the hottest temperatures at the station to “an oven.” He also acknowledged certain complications that already face the implementation of such a system, namely the fact that heat trapped in the City Hall station is not “in the same location” as the “place we need to get it to.”

The buildings that would receive the heat are also located in various jurisdictions and belong to various owners, Levine said, adding a further hurdle that the feasibility study will have to address.

Nonetheless, he clarified that the technology that would make up the “underlying mechanics” of the system—heat pumps and thermal transfers–are not as “exotic” as they sound, as they’ve been “used successfully all over the world.”

NY Governor Kathy Hochul, who has state control over the MTA, issued a statement that made clear her excitement over the feasibility project; she did not attend the press conference.

“Working with Mayor Mamdani and the MTA, we are harnessing cutting-edge climate technology for a truly cool purpose: making our subway stations tolerable during the summer and heating critical city buildings during the winter,” she said.