In a massive winter power outage, how would Minnesotans heat their homes?

I didn’t really plan to buy a home with an “octopus boiler” — a cast-iron leviathan whose asbestos-encrusted tentacles writhed through my basement. You could open what was once a coal hatch and peer into the belly of the beast, where a gas flame roared.

As hearthy as it was, the octopus was staggeringly inefficient, and I eventually replaced it with an ultra-high-efficiency computer-controlled boiler. Our gas usage plunged 20 percent, and all was well.

Until the power went out. In the dead of winter.

Turns out the octopus-era me had been warmed in a state of blissful ignorance, one of a dwindling number of Americans whose heat is not dependent on the electrical grid. Though my power outage lasted only a few hours, my home’s temperature plunged, and it scared the crap out of me. No one told me that efficiency’s trade-off was hypothermic risk.

According to Standard Heating President Troy Gregory, “For all the old octopus’s shortcomings, one positive was that all it needs is gas to keep operating. Unfortunately, with any system on the market today, you need both gas and electricity.”

In general, gas — which relies on buried lines — is more reliable. For example, in 2011, CenterPoint reported 27 gas service interruptions to state regulators. Xcel? 230.

One need only look at Hurricane Sandy to see risk realized and writ large. Thousands lacked electricity for weeks, frozen out of their homes in the late fall. Minnesota’s hurricane risk is laughable, but as extreme weather events soar, it isn’t hard to imagine a something like a giant ice storm wreaking havoc.

Minnesota’s emergency preparers haven’t thought much about home heating security. Minneapolis Emergency Management Director Barret Lane was “not aware of anything being discussed in the realm of emergency management around changes to boiler technology,” according to a spokesperson. Counterparts at three state agencies concurred.

There’s an objective reason for the complacency: Minnesota’s electrical grid has been pretty reliable despite the interruptions.

Keep in mind that while a house initially cools down fast, it’s a matter of “days, not hours” before you have to worry about pipes freezing, Gregory says. So how many day-plus outages does Xcel have? From 2008 through 2011, precisely 179 — affecting a grand total of 1,789 of its 1.2 million Minnesota customers, the utility says.

Mix in the odds of such outages happening on a frigid day, and you’re forgiven if, like policymakers, you’re unworried about the risk.

Full prepper

But let’s say you’re like me: a guy resigned to being the appetizer course in a zombie apocalypse, but full prepper at the possibility of a black swan freeze-out.

My first solution would likely be yours, if you have gas stove: grab the sleeping bags, manually light the oven, and open the oven door.

Unfortunately, Xcel frowns upon this. “The burning of natural gas produces carbon monoxide even when the over door is closed, and when the door is opened the CO is released into the kitchen and can build up to dangerous levels in the home,” says the company’s “Winter Outage Tips.”

(I suspect desperate, hypothermal homeowners will risk it, but you’ve been warned. Remember, your CO monitors stopped working in the outage.)

CenterPoint’s solution requires foresight and several thousand dollars: “We recommend having a natural gas fireplace for backup heat,” says spokeswoman Rebecca Virden.

A gas company recommending another gas appliance? Might seem self-serving (guess what the propane industry recommends), but there’s some logic and no small amount of irony.

Unlike your gas stove, the fireplace vents, so Mr. Sandman probably won’t provoke a permanent CO snooze. The irony is that the fireplace functions like a modern octopus boiler: some models still have standing pilot lights, which federal law prohibits in new boilers and furnaces.

Becker Fireplace Center owner Jim Eiynck says 90 percent of his sales involve a different, pilot-less technology known as ISI. Basically, a battery backup lights the pilot … if you remembered to stock batteries!

If you want to be off both the gas and electric grids, wood fireplaces are an option (though some kick out less heat) as are wood or pellet stoves. You’re still spending thousands of dollars putting one in, and you’d better stock enough fuel.

Batteries and generators

It’s tempting to think you can keep your heater’s brain running with the sort of cheap battery back-up you might have for your computer.  However, there are all kinds of problems here.

First, unlike your computer, your furnace doesn’t plug in. Unless your electrical skills are sharp, you’ll need a pro to hard-wire your system. Second, your furnace or boiler almost certainly has motors to push the air or water around, and those require more power than your computer.

Bruce Angeloszek, an East Coast installer doing land-office business in Hurricane Sandy’s wake, has put in battery backups charged by the grid (before an outage) or solar power. However, he says they’re far more expensive than fossil fuel alternatives.

“People who buy those from me are usually preppers or survivalists who don’t care financially and don’t want their neighbors to hear a generator and know they have power,” says Angeloszek, who notes Connecticut has suffered three black-swan outages since 2011. “I’ve had people offer to pay me in gold bullion.”

He estimates the cost of a whole-home solar-battery backup at $18,000 to $25,000 — on top of what you pay for a conventional solar install. You can limit the cost by only powering a few things, or hoping non-battery solar provides enough furnace power during the day to get you through the frigid night, but the initial cost is still high compared to anything running on dinosaur juice.

The other issue — which infuses the entire array of electric backups — is producing power that won’t fry computer circuits. “You need a clean sine wave,” Angeloszek explains. “People out here tried inexpensive generators and they didn’t have heat for long. You have to make sure your portable generator has an inverter if you have electronics on your heating system.”

And you still have to get portable power to the heating unit. Angeloszek favors a slick device called the GenerLink, which lets you plug your portable generator into the electrical meter, which already feeds your fuse box. You’d flip the switches to your heating circuits (and whatever else you could power) and be warm as long as the fuel holds out.

Problem is, while many Minnesota electrical co-ops allow the GenerLink, Xcel doesn’t. Curt Van Sickle, who runs the hydronics department for a large Minnesota home-seller, recommends the Interlock Kit, which does nearly the same thing in a few more steps via an exterior plug-in.

Again, you need a pro to do this — not just for your own protection, but to avoid “back feed” that can fry electrical-repair workers. Parts are several hundred dollars, and Angeloszek estimates install at around $1,000, on top of whatever you fork out for the portable generator.

For true paranoids, the crème de la crème is a permanent automatic generator. These natural-gas or propane-powered puppies — long used by businesses — automatically feed your fuse box when the power goes out. Residential models are hard-to-find nationally post-Sandy (Home Depot is back-ordered for weeks on the popular Generac models). Should you snare one, you can expect to pay $10,000 to $15,000 for a whole-home unit plus installation.

If it all sounds depressingly expensive, now you know why we rely on networked grids. For now, I’m pricing winter-camping equipment and figuring how how to drain my home’s pipes.