Remember the opening of the movie Taxi Driver ? In that iconic montage, cabbie Travis Bickle motors through the slick streets of New York City immersed in clouds of swirling steam rising from seemingly nowhere.
In the aftermath of the gigantic steam-pipe blast in midtown Manhattan last month, many have wondered what on earth such pipes are still doing under the streets of the big city. This is the Wireless Age, isn’t it, so why are conduits from the Steam Age still operating underground? Indeed, while most New Yorkers know that the city uses steam for something, they have little idea what that something is. Heating maybe? And visitors to the Big Apple are left in an even greater state of confusion. Locals have often smirked as concerned tourists, who have stopped to sniff the wisps of gas emanating from drain gratings, earnestly proclaimed to their friends, ”It’s okay; it’s only steam.”
If you’re among the many who haven’t a clue what all the buried steam lines are doing down there, you’re hardly alone. Even the editors at IEEE Spectrum have been wondering. So let’s try to get to the bottom of this vaporous mystery.
First, we have to know what to properly call the technology. That would be district heating--and it has been around for a long time. The ancient Romans developed a system of steam pipes to heat their homes and baths. Later, Europeans adopted the technique. And in 1877, inspired by the efforts of modern pioneers in steam power, such as James Watt, a hydraulic engineer named Birdsill Holly created the first commercially successful district-heating system, in the town of Lockport, N.Y. His idea caught on quickly, and soon district-heating schemes began popping up across the United States. The oldest Holly system still operating is in Denver, which started up in November 1880 and has been running ever since.
Holly’s little system became the foundation for the design of a much more ambitious project to supply power to the city of New York, as proposed by Wallace C. Andrews, one of the original directors of the Standard Oil Co. By 1880, Andrews had consolidated his efforts into the New York Steam Co., which mapped out a plan that divided Manhattan into 10 heating districts, each with its own central boiler plant and steam mains. The first of these was completed the following year. During underground construction of the first pipeline, Andrews often met with Thomas Edison, who just happened to be digging an underground network of his own to deliver electricity, according to a historical account published online by Con Edison Inc.
An expert in the field of district heating noted that a competing steam system under construction at the same time, in fact, failed because of technical problems in the design of its pipes. ”While Andrews and his engineer, Charles Emory, were installing their system, their competitor was installing one in the same streets, but it failed due to problems with explosions, one of which showered Tom Edison with debris,” said Morris A. Pierce, an assistant professor of history at the University of Rochester, N.Y., and the college’s energy manager.
By 1882, New York Steam was quite a success story, with 62 commercial customers signed to its service. Within four years, that number jumped to 350 customers, who received district heating from some five miles of mains below the bustling streets. Andrews’s firm expanded its coverage as the city itself grew, from Wall Street to Harlem, making improvements in the design of steam meters, controls, insulation, and even the pipes themselves.
As mentioned, New York Steam was hardly the only early player in the construction of the city’s underground infrastructure. The Edison Electric Illuminating Co. began delivering electrical power to downtown Manhattan the same year as Andrews’s steam operation. The New York Gas Light Co. and the Metropolitan Gas Light Co. had for years buried pipelines to offer gas and, later, electrical lighting. (This is not even mentioning the impact of the subway systems, rail lines, water supply conduits, and traffic tunnels of the 20th century--please see "How to See the Unseen City" for more on this topic.) And while they competed with one another, they also cooperated on many levels to supply energy to the public.
Pierce pointed out that steam systems using the basic Holly design, such as Manhattan’s, were always intended to also run generators to produce electricity locally. ”Indeed, the second Edison plant in New York City used steam from New York Steam,” said Pierce. ”Andrews’s plan included supplying steam to engine generators throughout Manhattan, since at the time steam could be transmitted farther than electricity using direct current. This relationship changed by the early 1890s, and electric power plants started providing exhaust steam and hot water to district-heating networks.”
This was all sorted out by 1954, when the various power companies completed decades of merger activities that saw one firm emerge to command all their interests: Consolidated Edison of New York. Today, Con Ed still boasts the largest district-heating system in North America. It operates seven steam-generation plants pushing some 30 billion pounds of pressurized vapor a year through 105 miles of mains and service pipes, providing heating, hot water, and air-conditioning to approximately 2000 customers in Manhattan and the surrounding boroughs. Many of these are well-known names: United Nations Headquarters, Grand Central Terminal, Pennsylvania Station, Rockefeller Center, and the Empire State and Chrysler Buildings, to name just a few.
The fact that Con Ed still uses steam power to provide air-conditioning to customers is one of the more curious wrinkles in the story of district heating in New York City. Pierce explained that Con Ed actively promotes steam for cooling in the summer, using steam-driven absorption chillers and turbine centrifugal chillers, and that ”many people have installed small steam turbine generators that fit right into Andrews’s original plan.”
This brings us back to our starting point. On the muggy afternoon of July 16, after a day of torrential rain, water had seeped into the underground maze of Manhattan’s infrastructure. A steam main laid in 1923 furiously exploded a block away from Grand Central, causing an eruption that sent rush-hour commuters running for their lives. Early speculation on the cause of the spectacular accident centered around an internal pipe condition called a water hammer, in which cool water mixes with steam and provokes an uncontrollable spike in pressure.
While Con Edison has yet to release a statement on the exact cause of the terrifying blast, it has posted an announcementonline that states the company will ”begin on-site fact-finding efforts to help determine the cause of this event” once repair work gets underway.
The dramatic July explosion has caused many to wonder if the days of district heating using steam are numbered ultimately. Rochester University’s Pierce is one of them. He observed that the largest system of this type in Europe is in Paris, but French authorities are now retooling it to run on hot water rather than steam, partly due to safety issues. ”They are planning to convert to hot water over time, since the losses and maintenance costs of steam systems are very high, and hot water is much more efficient when using cogeneration,” he said.
”The steam system in Manhattan will be around a while, although from an energy and environmental standpoint, it is relatively inefficient, expensive to maintain, and as you have seen, can be dangerous,” Pierce concluded.