When Superstorm Sandy shut down the lights over much of New York City in 2012, a number of facilities retained full heat and power. These places weathered the storm because they had cogeneration systems, better known as CHP or Combined Heat and Power Systems.
A CHP plant is an on-site system that combusts fuel (typically natural gas) to generate both heat and electricity. These systems are either “topping systems” or “bottoming systems”. Topping systems primarily use a heat engine to generate electricity but make use of the waste heat for buildings or industrial processes. Bottoming systems primarily produce heat for a facility but utilize wasted heat to generate electricity.
In either case, CHP systems are far more energy efficient than conventional systems that waste lots of energy. When the grid is out of service, CHP systems continue to supply power. There are now nearly 4,000 CHP plants in the US that produce 12% of the country’s electricity.
CHP is practical when the heat they produce can be used on site, as in a hospital, campus, or apartment building. During Sandy, the NYU campus, a 50,000-resident Co-Op City apartment complex in the Bronx, and South Hope Hospital on Long Island were all able to disconnect from the grid and maintain full power and heat for days until the grid was restored.
CHP is an example of a distributed energy resource, where power is generated where it is used rather than at a central plant. Like rooftop solar, CHP adds resilience and diversity to our rapidly evolving electrical grid.
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Web Links
CHP Kept Schools, Hospitals Running Amid Hurricane Sandy
http://www.ase.org/resources/chp-kept-schools-hospitals-running-amid-hurricane-sandy
Photo, taken on September 22, 2010, courtesy of Liberal Democrats via Flickr.
Earth Wise is a production of WAMC Northeast Public Radio. Support for Earth Wise comes from the Cary Institute of Ecosystem Studies in Millbrook, NY.