What’s the difference between an outdoor skating rink and an outdoor pool?

Technology |  2 min. read

On New Year’s Day, the Boston Bruins and the Chicago Blackhawks play the NHL’s first outdoor game of the season (in the legendary football stadium at Notre Dame).

If it weren’t for petrochemicals though, the players might need hip waders instead of skates.

The Midwest can be mighty cold in winter, but if January 1st turns out to be that one winter’s day when it’s sunny and in the mid-fifties – now Notre Dame Stadium is looking more like a backyard pool than an ice rink.

To the rescue – glycol, or more precisely in this case, ethylene glycol.  Glycol is what the NHL uses to make the ice, and to keep it ice.

And glycol, ethylene glycol, is made from ethylene – one of the basic petrochemicals produced from either petroleum or natural gas.

Now, if glycol sounds familiar (and it might), that’s because it’s also the stuff antifreeze is made of.  So now you might be thinking, “Wait a minute.  Antifreeze PREVENTS water from freezing, so how does that also turn water into ice?”

Here’s how:

  • In your car, the glycol goes INTO the water – and because glycol has a very low freezing point, it keeps the water in your radiator from freezing.
  • In a hockey rink, the glycol goes UNDER the water – and because glycol has a very low freezing point, it can keep the water frozen, and still keep circulating underneath.

The NHL brings a mobile refrigeration unit, aka a truck with a freezer, to the outdoor games.  Then the glycol moves through pipes under the ice, through the chiller in the truck, and back under the ice – over and over during the game to keep the ice frozen.

It can take up to three days ahead of time to make the two inches of ice needed for a game.  To make that ice, the water is poured over those pipes filled with VERY cold glycol.  And to keep yesterday’s ice from thawing today – the NHL puts a big plastic (also petrochemical-derived) blanket over the ice when they are not working on it.

And that’s just the tip of the ice(berg).  Petrochemicals are a part of hockey from the puck to the pads (sticks too).  You can find out all about that in Lord Stanley’s Cup.

By the way, the other outdoor game this season comes in February, when the Pens and the Flyers play for Pennsylvania bragging rights in Philadelphia.  And when the puck drops, yep, glycol will be there – keeping it chill.