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A Nobler Gas: Reducing CO2 use at craft breweries

by | Jun 8, 2022

Joel Mahaffey of Foundation Brewing. photo/courtesy Foundation Brewing

The rising price of gas has us all nervous, right? But I’m not talking about gasoline. The cost of carbon dioxide is going up, as well, and not just the environmental cost, but the price per pound of CO2 delivered to your local brewery.  

Carbon dioxide? you ask. The greenhouse gas that yeast releases during fermentation? Why would a brewery need to buy CO2 if the yeast are happily burping it for free as they transform malt sugar into alcohol? Every brewery tour guide loves to show the blow-off hose venting CO2 from the fermenter into a five-gallon bucket of sanitized water. That CO2 just escapes into the brewery, where it’s eventually vented and contributes ever so slightly to the climate crisis. Why don’t brewers just capture and compress that CO2 to use at other stages of production?

Joel Mahaffey, the co-founder and head brewer at Foundation Brewing in Portland, explained that it’s not that simple. “There are some companies working to scale that [carbon-recapture technology] down to breweries of our size,” he told me. “Previously that has only been available to 100,000-barrel breweries and larger.”  

There’s only one company in Maine that brews 100,000 barrels a year, and if you think they aren’t trying everything they can to reduce their carbon emissions, then you don’t know Allagash Brewing. Recapture may not be feasible at Allagash just yet, but some interim steps are significantly reducing both carbon consumption and emissions.  

Mahaffey joined his wife, Dr. Christie Mahaffey, to present Foundation’s carbon-abatement work to the New England Beer Summit last March.  Christie’s doctorate is in mechanical engineering, so as her husband and brewers at Allagash got to work reducing carbon, she handled the science-related tasks.  

Brewers use CO2 in five ways while making beer. First, the gas propels beer through hoses without oxygenating it as it moves from one vessel to another. Second, CO2 fills the headspace in brewing vessels so the beer doesn’t oxidize as it’s fermenting. Third, the gas is added back to beer after fermentation to give it the proper fizz — a process called conditioning, which occurs in a brite tank. Fourth, cans are purged with CO2 before being filled with beer (again, to protect against oxidation). And finally, CO2 propels the beer from the kegs through the taps in the tasting room. 

That’s a lot of carbon consumption, but Foundation has reduced the stages in which it’s used from five to three, and has implemented a way to reduce both consumption and emissions in a fourth. By substituting nitrogen for CO2 in the hoses and vessel headspace, the brewery is utilizing a lower-impact gas and saving money. “Nitrogen has a significantly lower impact on the environment, and is also about a quarter to one-fifth the cost of CO2,” Joel Mahaffey said. “There was some plumbing to run, but that cost was nominal.”  

As for the CO2 that the yeast burp while they make our alcohol, Foundation has begun recapturing and reusing some of that. By installing a device called a spunding valve, they’re able to channel some of that CO2 back into the beer, thus requiring less carbonation in the brite tank. “We still top up the carbonation on our beer,” said Joel. “We are able to capture about 70 percent of the needed carbonation in our beer when everything goes according to plan. If we had fermenters that were rated for higher pressure we would be able to capture more.”  

Spunding is not new technology — the brewers at Jack’s Abby Craft Lagers studied it in Germany before adopting it in 2015 — but Foundation is apparently the first brewery in Maine to use it. The brewers at Jack’s Abby say spunding gives their beer a brighter flavor and more consistent mouthfeel, claims that Joel Mahaffey confirms. “For lager beers, [spunding] will reduce ester production,” he said. “We began by using it for lagers, but expanded to other styles after finding secondary benefits…. I believe that capturing CO2 after dry-hopping (or coffee/chocolate/fruit additions) keeps aromatics in the beer that would otherwise be lost.”

In addition to working with their Industrial Way neighbors at Allagash, the Mahaffeys are eager to share what they know with other breweries — yet another example of the famously collaborative spirit that defines the craft brew industry. “I have told many folks about it,” Joel Mahaffey said. “Using nitrogen also is much safer with regard to chemical interactions. I would encourage anyone looking to reduce their CO2 costs or reduce their carbon footprint to pursue conversion, as it really was very easy to do.” 


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