Getting Up Close with Glycol | Craft Beer & Brewing

Getting Up Close with Glycol

Glycol systems, and the ways in which breweries control for temperatures in general, have improved quite a bit over the past four decades. Now they’re safer and more efficient than ever.

Brian Yaeger 4 months ago

Getting Up Close with Glycol Primary Image

Photo by Jamie Bogner

His Carolina-style barbecue joint in Seal Beach, California, was a fairly small spot that featured ten constantly rotating taps when it opened in 2006, but when he expanded to twenty-two taps within a year, Beachwood BBQ & Brewing’s Gabe Gordon pulled a MacGyver/Doc Emmett Brown hybrid and invented the mechanism he calls the Flux Capacitor. It’s the manifold that enables adjusting not just the gas pressure but also the specific blend of gases (carbon dioxide and nitrogen) that pushes beer through the tap lines.

“I never want to be the reason that a beer sucks. That’s why I made the Flux. Unless I was going through a keg in 3 or 4 days, when I tapped an IPA, the first day it had nice head retention and plenty of carbonation but by day 6 or 7, it didn’t feel as spritely,” he says. “Plus, when I rotated the lines, if I poured a tripel after that IPA, it poured foamy, or maybe a barleywine would become more carbonated after day 1. So I had to solve a very specific problem that’s intrinsic in long-draw draft systems that require cooling in line because the walk-in is so far from the taps.”

Compared to direct-draw systems, in long-draw draft systems, the source of the beer—typically a keg but sometimes a brite tank—is situated, by necessity, far from the faucet from which your pint of beer flows. In Beachwood’s case, that distance is sometimes as far as ninety feet. Given the quarter-inch trunk lines, that means that up to four pints of beer are chilling in the line between the keg and your glass. And by chilling, I mean hanging out—although, to make sure it’s not spoiling, it had best be chilled, too.

That’s where glycol comes into the frame.

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What’s Cooler Than Being Cool?

Glycol is a refrigerant, an antifreeze. It’s a viscous syrup that can come in ethylene (toxic) or propylene (nontoxic, and then it is generally polymerized into polypropylene). Brewers are, thankfully, prone to choosing the food-grade form in case there’s ever a leak into the fermentation tanks. And because that can and does happen, we’d all prefer glycol derived from, say, fermented beet sugar entering our beer should there be a small leak.

Having said that, fear not since glycol isn’t an ingredient in beer; it’s simply used in the process of producing beer. The chemical companies that manufacture glycol begin with the catalytic process called hydrogenolysis to convert vegetable glycerin (or glycerol) into propylene glycol. At high temperatures and pressures, the reaction between glycerol and hydrogen creates the glycol that enables the desired—and required—endothermic reaction involved in brewing beer efficiently. To think of it in kitchen or culinary terms, Night Lizard Brewing’s Cofounder and Head Brewer Chip Nasser suggests considering it as “the opposite of sous vide, creating a cold-water bath.” Night Lizard, 120 miles up the coast from Beachwood, programs their glycol system to run at about 30°F (-1°C), while some brewers set theirs as low as 25°F (-4°C). What’s more, the temperature of the refrigerant will be at least 10°F (6°C) below the temperature of the glycol solution, meaning that operating at 30°F (-1°C) glycol temperature means the refrigerant is 20°F (-7°C) or lower.

Nasser became a self-taught expert in his glycol system by building Night Lizard’s whole system himself to save tens of thousands of dollars, even if it took him several weeks instead of a day.

Put That in Your Pipe

The heart of Nasser’s system is a million BTU, two-stage, quad compressor American Chiller with a 500-gallon reservoir. That reservoir doesn’t hold 500 gallons of straight glycol, mind you. It’s 55 percent polypropylene glycol (which conveniently comes in 310-gallon totes) and 45 percent water, which sufficiently allows the water to chill down slightly below water’s freezing temperature when needed. While Nasser saved money by doing his own build-out, he didn’t skimp when it came time to purchase header lines, the highways that lead to everywhere chilling is required. “They’ve got the greatest R-value on the market,” crows Nasser.

R-value is the rate of heat dispersion, or for nonbrewers, the spec you look for in a highly rated sleeping bag to keep you from shivering through a cold night in the woods. In this regard, glycol can be viewed as something that helps save on utility bills the way not running your AC on warm days lowers your energy bill.

From the glycol chiller, the solution typically flows through header lines in a loop that leads through a brewery’s heat exchanger that cools the wort as well as the heat exchanger in the walk-in cooler or cold-storage room as well as the jacketed fermentation and conditioning tanks. Wherever there’s brewing equipment, there’s glycol coursing in it or nearby. Night Lizard’s lines happen to measure some 160 feet looping from the supply to the return.

Something Cold Something New

The Flux Capacitor—now installed in roughly a dozen elite beer bars including Jeppe Jarnit-Bjergsø’s Tørst across the country in Brooklyn—largely addresses an issue of gas and pressure since the majority of draft systems are designed to dispense what the majority of beer is: light American lager. But Beachwood Brewing makes a wide array of styles from IPAs to wild ales.

So, while light American lager wants to be served at 34°F (1°C) or as close to freezing as it can get, each beer in the style spectrum should have its own ideal dispensation temperature. Gordon includes temperature as a factor on the dispense side—especially since the colder beer is stored, the more carbonation it can absorb—but keeps the emphasis on gas and pressure, though the three factors work in unison to avoid a beer pouring too warm and foamy. To achieve this, Beachwood employs a power pack—a cheaper mini glycol system—for the service side separate from the larger system for the production side.

At Night Lizard, one glycol reservoir chills everything from the five unitanks (each with three-compartment jackets) and dual-jacketed brite tank to the cold box that’s thirty-three feet from the taps via their long-draw draft system. Many a brewery manager would scoff at this, but Nasser did it both for economic and environmental reasons, as it obviates refrigerant gasses.

Glycol systems, and the ways in which breweries control for temperatures in general, have improved quite a bit. Brewmaster Joe Thorner would know. His career has come full circle having started in 1978 at the former Stroh brewery in Detroit, and he’s now at Brew Detroit, where they contract brew Stroh’s Bohemian-Style Pilsner. During the intervening decades, he worked for Anheuser-Busch in New Jersey, Craft Brew Alliance in Washington and New Hampshire, and Boston Beer Company in Ohio.

Today, he’s the brewmaster and director of operations for Brew Detroit’s 68,000-square-foot facility. Under one roof, 2,500-gallons of 50/50 glycol solution are responsible for maintaining the temperatures of the 100-barrel brewery’s 400-barrel fermentors and double-barrel nano brewery.

“Mechanical refrigeration has progressed over the past 40 years in brewing,” says Thorner. “Back then, all breweries used ammonia for all the cooling out in the brewery with wort coolers and beer chillers being mainly shell-and-tube ammonia heat exchangers where ammonia was the main media for cooling on the shell side of the heat exchanger and wort was on the tube side of the heat exchanger.” These types of exchangers were used to cool propylene glycol for tank cooling and temperature control using ammonia. 

“There were a lot of safety issues with ammonia being out in the brewery, and there were deaths, injuries, and fires associated with accidents,” he says. “Over time, the ability to cool the glycol using electro-mechanical refrigeration has replaced the need for ammonia to cool the glycol down.”

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