New York's Steam System

Via The Dish, Mark Vanhoenacker describes the ConEd steam system under the streets of New York:

Con Edison, New York City’s venerable power company, pipes steam to customers in Manhattan just like any other utility product (such as gas, water, or electricity). The steam—some purposely created, some a ‘waste’ byproduct of electricity generation—comes from power plants.

Commercial, urban steam systems of this size are rare, and New York’s is the world’s largest. (Lockport, N.Y., had the world’s first urban steam system, in 1877, and Denver’s is the world’s oldest in continuous operation.) NYC’s system has 105 miles of main pipes, 3,000 manholes, and reaches around 1,800 buildings—everything from the Empire State Building to United Nations Headquarters. Steam connections run from the southern tip of Manhattan to 96^th Street on the West Side and 89^th Street on the East Side.

What’s the steam used for? A little bit of it is used as, well, steam—to operate laundries and even to sterilize hospital equipment. But a lot of it is used to heat buildings and their water supplies. Surprisingly, given that the steam’s temperature is around 350 degrees Fahrenheit, it’s also used to cool buildings, via the dark magic of absorption refrigerators. According to Michael Clendenin, director of media relations for Con Edison, the use of steam to cool buildings results in a big reduction in summer demand on the electricity grid.

Urban steam systems offer significant advantages, because a large power plant is generally much more efficient than individual boilers in buildings. Measures to reduce air pollution can be centralized, too.  But given the significant cost in infrastructure—a whole set of pipes under a city doesn’t come cheap—urban steam makes most sense in densely populated areas. Manhattan, say.

That is a pretty amazing system.  The company I work at is one of several in our town who used to buy steam from the city's coal-fired power plant.  Once they shut down the turbines, they put in a gas boiler to continue to provide steam to local businesses and at least one school.  Eventually, they shut the gas boiler and got out of the steam business.  It was always cool to see steam rising out of a catch basin at one of the intersections in town in winter time.  We were working on a storm sewer project one time, and you could actually tell where the steam line ran down the street because the rest of the street had some snow on it, and the path of the steam line was clear.  Anyway, the New York system is massive.  This is pretty impressive:




That must be a massive steam main.