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Downtown Chicago Is One Giant Ice Bear

By JoshMogerman in News on Dec 23, 2012 5:00PM

Thermal Chicago - P2 Plant [SolarWind]

Despite the overhyped winter storm predictions this week, we have not seen much ice in Chicagoland this year. That’s why a Trib article trumpeting the arrival of an “ice bear” in St. Charles caught our eye. No, it's not a new denizen added to a far-flung suburban zoo, this is basically a giant air conditioner with a built-in tank for freezing water overnight when electricity rates are at rock bottom. The unit saves its building boatloads of cash by using that cheaply made ice to cool the building throughout the day when electricity rates skyrocket.

Here’s the thing. Downtown Chicago is really one giant ice bear.

Ever notice the weird looking building on the River just east of where I-290 crosses through the old Post Office? It is run by Thermal Chicago and goes by the decidedly unflashy moniker of P2. The building anchors Chicago's "district cooling system" that employs a 14-mile maze of pipes to chill 45 million square feet of space in 100 downtown and River North buildings. The concept is not unique, you can find a similar scheme in plenty of cities, but Chicago may very well boast the biggest cooling network on the planet. And as downtown hosts more and more IT infrastructure and data centers, delivering chilled water is big business year-round even as the mercury plunges outside.

P2 is basically the world’s biggest icemaker--a giant freezer built around a 40-foot deep, two-million gallon water tank with hundreds of miles of cooling coils wound up in the middle. Like the Ice Bear, it is busy freezing the tank at night when electric costs are minimal. During the day, that ice feeds chilled water to vast chunks of the Loop and cools warm water that returns from the buildings on its thermal network. There are chilled water plants elsewhere on the network in the Merchandise Mart, the former IBM Building on Wabash and the Blue Cross/Blue Shield building on Randolph. They use an array of condensers, heat exchangers and other technologies. The Mart and IBM locations use water sucked out of the Chicago River, which must be treated with ultraviolet light to kill off some of the funk before being used to cool the system.

If you are feeling cold while walking down LaSalle or Dearborn, just know it could be a lot chillier underfoot, where near-freezing water courses mere inches below your feet all day long. For a closer look at this complicated, nearly invisible system, check out these videos:

The…umm…perky folks on WCIU’s “You and Me This Morning” paid a visit to P2 over the summer:

For a more technical look at Chicago's district cooling system, check this out: