On Thursday morning, just before the height of the morning rush hour, an 83-year-old steam pipe exploded underneath 5th Avenue in the Flat Iron neighborhood of Manhattan. The force from the ruptured pipe broke through the street, launching concrete and debris into the air, and injuring five people. As morning commuters filed into the area, they were faced with a white pillar of steam extending hundreds of feet towards the skyline. Several of the buildings in the immediate vicinity were evacuated, but it was not until later in the morning when reports of possible asbestos contamination demanded the further evacuation of 49 buildings in the surrounding downtown area. After confirming the presence of asbestos in the insulation around the pipe, the City of New York is undertaking ongoing efforts to assess indoor and outdoor air quality, and the facade and ventilation systems of surrounding buildings will need to be tested for the presence of asbestos fibers.1 All told, recovery from this accident will likely cost millions.
The ruptured pipe is part of Con Edison’s district steam heating system, the largest of its kind in the country. Using over 100 miles of underground pipes, the utility distributes high temperature steam to more than 2,000 buildings in Lower Manhattan, providing them with space and water heating and cooling. The steam is generated at seven regional power plants, where it is first used to turn a turbine to generate electricity before being distributed throughout the district heating pipeline network. By harnessing the thermal energy from the power plants, district heating removes most demand for distributed boilers and space-heaters, improving indoor air quality and significantly reducing regional carbon emissions. This method of using steam for both electricity generation and heat is call cogeneration, and in cities all over the country it is being used to save millions of metric tons of carbon dioxide from entering the atmosphere every year. These steam networks are extremely valuable assets in urban efforts to reduce locally produced greenhouse gas emissions; however, as exemplified by Thursday’s explosion, these systems are vulnerable to failure, despite ongoing maintenance efforts.
Construction of New York’s steam system began in 1882 and in recent years it has started showing its age. Clogged pipes are leading to the inefficient distribution of heat, and between 1986 and 1997, at least a dozen pipes ruptured, killing several people and injuring many more. In most of these explosions, asbestos contamination was recorded in the area. A decade later, a steam explosion near Grand Central Station killed one person and injured more than 30. A decade since then, Thursday’s explosion should alert us to the fact that deferred maintenance is endangering both civilians and the long-term economic viability of the systems as a whole. Con Edison’s steam system may be one of the oldest and largest district heating systems in the country, but many other cities have significant steam networks that are not much younger. Veolia’s steam loop in Philadelphia, for example, was built in the 1920’s and serves over four square miles in the city center.
The story of these utility cogeneration systems is all too familiar when it comes to discussing urban infrastructure. District heating networks are assets that cities could utilize to further improve their efficiency, sustainability, and livability; however, doing so will require a major investment to repair and replace aging systems. Unless public and private investment significantly outpaces attrition, customers and utilities will eventually abandon these systems in favor of distributed gas, oil, or electric heating capacity, sacrificing one of our greatest assets in the fight against climate change and urban air pollution.
- Asbestos is a classification of fibrous silicate mineral that has been used extensively as insulation because of its excellent heat resistance. Despite early 20th-century reports of asbestos inhalation causing pulmonary disease and cancer, the United States government did not severely limit its use in buildings and infrastructure until the 1970’s. Therefore, asbestos exposure continues to be a serious public health concern in older cities today.