It turns out that Con Ed has been piping steam–which is a by-product of power generation, naturally–to buildings throughout lower Manhattan since 1882. (The pipe that blew up dates to 1924.) Incredibly, the system, which includes 7 plants, one with a boiler 8 stories tall, produces an average of one million pounds of steam per hour.

The reason that’s interesting, at least to me, is that this is a prime example of what’s known as combined heat and power generation. It’s an old idea, but one that’s making a resurgence as bills for all our petroleum-dependent energy sources–heating oil, natural gas and electricity–continue to climb. As we all know, the easiest way to “generate” more energy per dollar spent is simply to conserve.

You might also wonder, as I did, why the heck these pipes are pressurized even in the middle of July–clearly the steam isn’t being piped into radiators. Here it turns out that an additional cleverness has been introduced into the system: buildings in the financial district use the steam to power the compressors that run their massive air conditioning units.

The whole thing is rather brilliant–a model of re-use and smart urban planning–that is until disaster strikes. Apparently there have been lethal steam pipe explosions before, the most recent in 1989 in Gramercy Park. There’s a movement to bring these kinds of combined heat and power systems to cities small and large throughout the U.S., since it’s more efficient to combine the two functions and reuse the “waste” products of the power generation process.