When beer lovers are asked to name the ingredients that go into making their favorite products, yeast, barely, hops and even water are likely to elicit the most frequent responses. But as many in the industry have found out recently through a shortage, carbon dioxide plays an equally important role in creating the appearance, flavors and mouthfeel consumers look for in their beers.
"Without it, beer is not a palatable, enjoyable beverage," said Chuck Skypeck, technical brewing projects manager with the Brewers Association. "It's truly an ingredient and maybe unsung."
Carbon dioxide is akin to adding salt to items when baking or cooking in that it helps enhance the other flavors prevalent in the beer. The colorless gas also maintains the iconic foam head on a beer after it's poured, and can help brewers alter the pH of the beverage to create just the right flavor — lower pH produces a more acidic profile. There are other advantages, too, as extra CO2 creates a crisper taste and lifts out the aroma of the beer just before it's consumed.
At Harpoon Brewery, a craft operation making beer in Boston since 1986, the brewer goes through as much as 1,000 tons of liquid CO2 each year, or the equivalent of roughly 16 to 20 tons a week.
"It's a large cost throughout the year," according to Al Marzi, Harpoon's chief brewer who estimated the brewer spends more than "six figures" on CO2 each year. "It's not as expensive as glass or cans or malt but it's somewhat significant."
The lion's share of the CO2 used by beer companies doesn't go into the beer itself, but rather to process it. When beer is moved from the tank it is fermented into another where it will be packaged, the tank, lines and other equipment is purged with CO2 to rid it of any oxygen that could cause the beer to go stale faster. Cans and bottles also are doused with CO2 for the same reason.
"Without it, beer is not a palatable, enjoyable beverage. It's truly an ingredient and maybe unsung."
Technical brewing products manager, Brewers Association
Harpoon and other brewers generate their own CO2 naturally during the beer-making process when the yeast and the fermentable sugars from the malt combine together, causing the malty sweetness to be converted into alcohol, heat and the gas. But much of the CO2 ends up being vented out of the tank because it has a lot of volatile aromas, sulfur compounds and aromatic smells that would negatively impact the beer. As a result, CO2 has to be trucked into the facility where it is stored.
CO2 is a popular ingredient in the food and beverage space. In addition to beer, the gas is incorporated into hard ciders, sodas, carbonated water and other drinks. Reed's, a maker of ginger food and beverages and Virgil's root beer, uses CO2 in all of its drinkable offerings. CEO Norman Snyder said the company would have to alter the recipes for some of its products if it no longer had access to CO2. While it hasn't gotten to that point, Snyder said there were times this summer where Reed's was worried about its CO2 supply arriving.
"If something happened and say CO2 stopped or it became illegal to use, I think the ginger beer we'd have more flexibility" in reformulating, Snyder said. "We'd have to pick some of our sodas that we could reformulate, but some of them I don't think we could pull off."
Bill Baker, vice president of business development at Airgas, a U.S. supplier of industrial, medical and specialty gases, estimated about two-thirds of purified CO2 sold in either liquid form or as dry ice in the United States is used for food processing, packaging and transporting items, as well as for beverage carbonation.
"Over time, CO2 demand has grown steadily but modestly, " Baker said in an email. "Since a majority of CO2 is consumed by food and beverage applications, growth rates tend to be influenced largely by those demographics."
While carbon dioxide is sought after in beer, sodas, meats and other products, it's generated as a byproduct in the production of ethanol, oil, fertilizer and ammonia — there are even a handful of pipelines and natural wells where the gas can be recovered. CO2 is transported and stored as a cryogenic liquid, which requires specialized equipment, including trailers and railcars. Longer transport distances add to the cost, Baker said.
Technology to capture CO2 is used by large brewers and a handful of smaller ones — like those in Alaska where it can be expensive to get the gas transported, or larger craft players where size allows them to recover a sufficient amount — but for the most part, manufactures have to purchase it. The dependence on other industries can sometimes create problems.
Earlier this year, ethanol production cratered as the coronavirus curtailed how much consumers were driving. The reduction in miles cut demand for ethanol, which is blended into most gasoline sold around the country. Ethanol alone is responsible for about 40% of CO2 used in the U.S., Skypeck said, meaning with production of the corn-based fuel down roughly 50% from a year ago, the overall supply of the gas is down close to 20%.
CO2 production has improved since then, but those in the industry said supplies remain tight. The challenges have been exacerbated in parts of the country by recent hurricanes in the southeastern U.S. and fires in the West that have either made it harder to move CO2 around, or caused oil refineries that produce the gas to go down.
“This whole shortage has kind of changed my thinking about it,” Skypeck said. “I was in that former class of just not thinking about it as an ingredient but without it, it’s not beer. I’ve really changed my thinking about beer ingredients, and including CO2 in that.”
Marzi agreed, noting that Harpoon and other users of CO2 are paying more attention to how efficiently they use the gas. "Other than testing it to make sure it's pure, we don't pay attention to it, you just expect it to be there, so it doesn't become an issue until suddenly you go, 'Wait a minute, what do you mean I'm not getting a delivery today? ' "
There are a limited number of substitutes that beer makers can use if they can't procure CO2. Nitrogen, for example, can cleanse pipes and equipment of oxygen, but its use in beer itself is limited. Nitrogen causes beer to feel creamy, which works for brews like Guinness but could taste out of place for most IPAs or crisp pilsners.
"In terms of being in the beer, there is not a good substitute for CO2," Skypeck said. "There are alternatives, but you're getting different results."