Why I might not want an electric blanket that cools me

Matt: Even here in America’s Finest (Weather) City, most every household undoubtedly contains at least one electric blanket. But why aren’t electric blankets to provide cooling available in stores, too? Since electricity is used in the creation of refrigeration and air conditioning could it not also be made to cool a blanket? —A the Z, University Heights

It could and it is, A, but if you want one, you’ll have to throw out your spouse or a nightstand or something to make room for the compressor and related machinery. A cooling blanket is a common piece of hospital gear that chills patients with circulating water. Cooling vests for combat helicopter pilots work on somewhat the same principle; and a decade ago, a Japanese company marketed (unsuccessfully) an electric pillow to cool your hot head.

But even now I hear you saying, “Matt, you pea brain, I mean a regulation household electric blanket, not some piece of industrial gear.” And I hear me saying, “Well, let’s ask the thermoelectrics experts." They don’t come any expert-er than Dr. Mathiprakasam of Midwest Research Institute, Kansas City, Moe, the think tank that developed those pilots’ vests. So, Dr. M., what’s the deal? The deal is that it’s more complicated to cool something than to heat it. There’s a reason why a space heater is simpler than an air conditioner.

Let’s take the common household six-pack, f'rinstance. Put it in the sun, and the heat energy is transferred efficiently into the cans. End of story. But when you pitch the cans into the refrigerator, the cold air has to suck the heat back out of the beer to cool it. Cooling is heat moving out of something, not cold going into it.

But now you have this big gob of sucked-out beer-can heat You can’t leave it in the fridge, or everything would turn all tepid and droopy. So the heat’s taken up by coolant coils, and the coils release it into the room. When you cool something, you produce waste heat — about two units of heat for each unit of cooling, according to Dr. M., a problem they’d love to solve.

Which brings us to your bed chiller. Suppose we could devise a nice plug-in, solid-state blanket filled with thermocouples that pull the heat away from your sweaty body. As Dr. M. envisions it, you’ll be cool under the blanket, but given today’s technology, you’ll be able to melt cheese on the top. I suppose we might turn this into a marketing plus — fix breakfast while you sleep.... But practically speaking, the cooler you get, the warmer your room will get, so you’ll probably have to turn on the A/C anyway, thus solving your original problem without inventing a cooling blanket. It’s theoretically possible but won’t show up under your Christmas tree any day soon if we don’t hang up the phone now and let Dr. Mathiprakasam get back to work.

A friendly, lavender-scented note to you e-mailers from Grandma Alice, doyenne of the Matthew Alice Communication Center and Oatmeal Cookie Institute. The normally sweet lady is a guerrilla-warfare spam fighter, hammering the delete button with gusto — we might even say relish (Spam and relish being an old Alice family favorite). In her fervor, she admits, she refuses to read the stuff so might occasionally delete a legitimate query not adequately identified in the subject line. We trust the recent “Turn Your Washing Machine into a Cash Cow!” was spam, not a question, but it’s not always so clear. Please, Grandma asks, make your intentions obvious in the subject line, even if your question is, “Matt, how can I turn my washing machine into a cash cow?”