San Francisco Beer Week, a celebration of the latest and greatest in Bay Area beer, is set to star an ancient ingredient rather than an experimental new one. Or really, kveik might be both: A traditional Norwegian yeast, it’s centuries old — but brand new to American brewers like Almanac owner Damian Fagan, who just learned about kveik last year.

“It’s too early to say this for sure, but this could have pretty significant impacts — not just for Almanac, but for the whole industry,” Fagan says.

In that case, better learn how to say it. Kveik is pronounced “kwike” (it rhymes with bike). It’s a hardy yeast that rural Norwegians have used for generations to make their own farmhouse beers, sometimes storing the dried out, dormant yeast on a wooden kveik ring that resembles a blocky necklace. When it’s time to make more beer, they dunk the ring into malty water to reanimate the yeast.

“Orange-y is the main flavor I get from it” says advanced cicerone and kveik booster Chris Cohen. “You can do an IPA and make choices that accentuate that [flavor] or do a winter warmer where that character doesn’t make too much of an appearance, it’s just in the background.”

This could have pretty significant impacts — not just for Almanac, but for the whole industry

The appeal of kveik to modern brewers — who definitely won’t be be using wooden rings except for show — is speed and efficiency. But drinkers, who are newly wild about “expressive” yeasts and their origins (think Vermont) might like the flavor and novelty, too.

They’ll soon find out: This year, one of the five official Brewer’s Guild collaboration beers is fermented with kveik, and the yeast is the star of its own party at Bernal Heights beer bar Old Devil Moon.

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Working with Cohen and Henhouse Brewing, Almanac just brewed its second-ever beer with kviek, a double IPA called Oslo Hot Chicken. With typical brewer’s yeast, which operates at temperatures of 55 to 70 degrees, it would have taken weeks to ferment the new beer. But with kveik yeast, Oslo Hot Chicken fermented at 100 degrees. And since hotter means faster, the team, which brewed their beer on Thursday, was drinking it on Sunday night. By Monday it was in kegs and on tap in bars.

“That’s pretty profound,” says Fagan.

Fermenting beer at hotter temperatures is easier — no need to waste energy cooling it all the way down from the boil — and more energy efficient. Brewers would do it more often if typical yeast could handle it.

And brewing beer twice as fast could also mean brewing twice as much. For small craft brewers maxing out their current capacity, using kveik might suddenly double their output.

“You can literally churn out twice as much beer with the same equipment [using kveik],” says Lance Shaner, co-owner of Chicago’s Omega yeast labs, which sold its yeast to Almanac.

In Norway, kveik strains vary from house to house and village to village, as farmhouse beer expert Lars Garshol explains on his popular website Larsblog. In the past few years, he’s tracked down generations-old kveik strains in areas like Voss, Norway, sending them back to labs like Omega.

Omega’s three kveik strains, HotHead Ale, Voss Kveik, and Hornindal Kveik — refined kveik strains derived from Norwegian originals — have grown increasingly popular, Shaner says. Collectively, they’re the third-best seller out of Omega’s 80 yeast strains.

“Revolution might be taking it a bit far,” says Shaner, “but they’re going to have their place for sure.”

Chris Cohen, who co-owns Old Devil Moon and organized the bar’s kveik-focused event, is less cautious in his predictions.

“This is coming like a tidal wave,” he says. “It’s going to change the whole industry.”

Cohen’s “Norweigan kveiking raid” will feature about 14 kveik beers, including ones Cohen sampled at a farmhouse beer festival he visited in Norway this summer, plus several he’s brewed since then in collaboration with locals like Almanac and Freewheel.

This is coming like a tidal wave

While they’re all made with kveik, that doesn’t mean they’ll taste the same. And beers like “Valley of the Dragons,” a double IPA made with kveik that’s the official Silicon Valley beer week brew, “would be unrecognizable,” to a Norwegian, says brewer Ryan Bridge, who fermented his beer at 100 degrees at Strike Brewing Co. in San Jose.

“The traditional [Norwegian farmhouse brews], those drinks are like 12 percent, and you drink them out of a wooden bowl,” says Bridge.

Those beers, like one made with juniper called maltøl, probably wouldn’t be a hit with his drinkers, either. “I think I’d have trouble selling [what tastes like] a bowl of banana juice,” Bridge jokes.

In that regard, he might be underestimating the curiosity of beer drinkers, who are liable to try anything once. But kveik doesn’t have to be a fad.

“We’ve seen everything from soup to nuts in craft beer,” says Almanac’s Fagan. “A lot of it’s been stunts, but here’s something that’s a useful, beneficial, productive resource. I can’t imagine we won’t see it grow into the broader beer market.”