Heating system in New York: The Big Apple has been steaming for 140 years

Steam rising from manhole covers: an image from New York that many people are familiar with. Behind it is a heating system that is now somewhat outdated.

The motif should not be missing in any New York film: Smoke rises in the street canyons of Manhattan – sometimes through orange-colored plastic chimneys, sometimes simply from the manhole cover. Generations of tourists have already racked their brains as to what could be the reason. The answer is simple and, by American standards, ancient: a steam heating system in Manhattan’s underworld.

Steam heating also at the 9/11 Memorial

“The steam system went into operation in March 1882, so we just celebrated our 140th anniversary,” says Frank Cuomo. “A few years earlier, the system was invented in Lockport, New York State. That idea was then implemented on a large scale as New York City expanded north from Battery Park.”

Cuomo is responsible for the steam heating system at the New York energy supplier ConEdison. It is 170 kilometers long and supplies around 1,600 buildings in the city with steam for heating – up to three million people in an area of ​​more than 460,000 square meters from the Empire State Building to the headquarters of the United Nations.

“If a tourist knows the name of a building, then there’s a good chance we’re supplying steam to it, too. Because a lot of these buildings were built around the time the piping system was built,” Cuomo said. A famous exception is the World Trade Center: “The old complex was already supplied with steam, but so was the new complex. From the towers to the water basins. There the water is heated with ConEdison steam so that it does not freeze in winter.”

Only blackout brought system to a standstill

Only once in the 140-year history of New York’s steam heating system did the system come to a standstill throughout the city: in 2003 during the major blackout in the north-east of the USA and Canada, when 55 million people were without electricity, some for days. But almost every day there are minor local failures in the meanwhile somewhat dilapidated line system. And then smoke rises from the New York underground, Cuomo explains.

“There can be two reasons for this: firstly, a leak in the system that then has to be patched, which can be very time-consuming. Or, secondly, if our steam lines come into contact with water.” The steam lines are more than 200 degrees Celsius hot. “Wastewater or rainwater then evaporates immediately and comes out of the street or sidewalk somewhere as a cloud.”

And then the orange plastic chimneys come into play, which – like so much else in the city – are considered “iconic” in marketing-speak. They should only ensure that pedestrians do not scald themselves and that the view of car traffic is not blocked.

Old, but comparatively environmentally friendly

But despite the vulnerability of the system, the New York steam heating system is comparatively environmentally friendly. 60 percent of the required energy is generated with waste heat from local power plants, as with district heating in Germany. Only that steam is produced instead of hot water.

“The advantage is that no additional pump energy is required, as with hot water,” explains Cuomo. “The steam goes straight to the customer’s site because of the pressure.” And that can also be very tall skyscrapers. “The steam reaches the top floors without the need for additional energy.” Why do climate protectors conjure up the renaissance of the system.

Someday hydrogen instead of steam?

But the crux of the matter is: as long as the steam is generated in conventional power plants with fossil fuels – in New York it is 97 percent natural gas – the steam heating system will not really be CO2-neutral either. Water vapor is difficult to generate with solar or wind energy.

And so Vijay Modi from New York’s Columbia University is backing another idea: “Perhaps it will be possible to convert large amounts of electricity from the offshore wind farms off New York into hydrogen. Then we could use the old steam pipelines to supply the buildings with supply hydrogen for heating.” There are still a lot of technical questions unanswered, but: “At least you wouldn’t have to build a new distribution system, you could use the old pipelines.”