When beer enthusiasts are prompted to list the key ingredients in their favorite brews, they typically mention yeast, barley, hops, and even water. However, recent shortages have revealed that carbon dioxide is just as crucial for creating the appearance, flavors, and mouthfeel that consumers expect in their beers. “Without it, beer is not a palatable, enjoyable beverage,” stated Chuck Skypeck, technical brewing projects manager at the Brewers Association. “It’s truly an ingredient, perhaps an unsung hero.”
Carbon dioxide functions similarly to how salt enhances flavors in cooking or baking. This colorless gas not only sustains the characteristic foam head on a poured beer but also allows brewers to adjust the beverage’s pH to achieve the desired flavor—lower pH results in a more acidic profile. Additionally, CO2 contributes to a crisper taste and intensifies the beer’s aroma right before consumption. At Harpoon Brewery, a craft brewery based in Boston since 1986, the brewer utilizes approximately 1,000 tons of liquid CO2 annually, which amounts to around 16 to 20 tons each week. “It’s a significant expense throughout the year,” said Al Marzi, Harpoon’s chief brewer, estimating that the brewery spends over “six figures” on CO2 each year. “While it’s not as costly as glass, cans, or malt, it is still quite significant.”
Most of the CO2 used by breweries doesn’t go directly into the beer; instead, it is employed in the processing stages. When transferring beer from fermentation tanks to packaging tanks, CO2 is used to purge the tanks, lines, and equipment of any oxygen that could spoil the beer. Cans and bottles are also treated with CO2 for the same purpose. Harpoon and other breweries generate CO2 naturally during the brewing process when yeast interacts with fermentable sugars from the malt, converting malty sweetness into alcohol, heat, and gas. However, a considerable portion of this CO2 is vented out due to the presence of volatile aromas and sulfur compounds that could adversely affect the beer’s quality. Consequently, CO2 must be delivered to the brewery, where it is stored.
CO2 is a popular ingredient in the food and beverage industry. Beyond beer, it is also used in hard ciders, sodas, carbonated water, and other beverages. Reed’s, known for its ginger products and Virgil’s root beer, incorporates CO2 in all its drink offerings. CEO Norman Snyder indicated that the company would need to adjust its recipes for some products if CO2 became unavailable. Although this situation hasn’t arisen yet, he mentioned that there were moments during the summer when Reed’s was concerned about its CO2 supply. “If something happened and CO2 were to stop or become illegal, I believe we’d have more flexibility with ginger beer in reformulating,” Snyder remarked. “However, for some of our sodas, I doubt we could manage it.”
Bill Baker, Airgas’s vice president of business development, estimated that about two-thirds of the purified CO2 sold in the U.S., whether in liquid form or as dry ice, is utilized for food processing, packaging, and beverage carbonation. “Over time, the demand for CO2 has steadily but modestly increased,” Baker noted in an email, adding that most CO2 consumption is driven by food and beverage applications.
While carbon dioxide is in demand for beer, sodas, meats, and other products, it is also produced as a byproduct in the manufacture of ethanol, oil, fertilizer, and ammonia. There are even pipelines and natural wells where CO2 can be extracted. The gas is transported and stored as a cryogenic liquid, necessitating specialized equipment such as trailers and railcars, with longer transport distances increasing costs.
Large breweries and a few smaller ones use technology to capture CO2—particularly in Alaska, where transportation costs can be high, or among larger craft breweries that can recover enough gas. However, most manufacturers still rely on purchasing CO2. This dependency on other industries can create challenges. Earlier this year, ethanol production plummeted due to reduced consumer driving amid the coronavirus pandemic, leading to a significant decline in CO2 supply. Skypeck noted that ethanol accounts for about 40% of the CO2 used in the U.S. With ethanol production down nearly 50% from the previous year, the overall CO2 supply decreased by approximately 20%. Although CO2 production has improved since then, industry insiders report that supplies remain tight. Recent hurricanes in the southeastern U.S. and wildfires in the West have further complicated the situation by disrupting CO2 transportation and affecting oil refineries that produce the gas.
“This shortage has shifted my perspective on CO2,” Skypeck admitted. “I used to overlook it as an ingredient, but without it, it’s not beer. My views on beer ingredients, including CO2, have truly evolved.” Marzi concurred, acknowledging that Harpoon and other CO2 users are now more mindful of their gas consumption. “Aside from testing to ensure its purity, we didn’t pay much attention to CO2; we simply expected it to be available until suddenly faced with a delivery issue.”
Beer makers have limited alternatives if they cannot acquire CO2. Nitrogen, for instance, can be used to purge oxygen from pipes and equipment, but its application in beer itself is restricted. Nitrogen creates a creamy mouthfeel, which suits drinks like Guinness but may not be appropriate for most IPAs or crisp pilsners. “In terms of beer, there isn’t a suitable substitute for CO2,” Skypeck emphasized. “There are alternatives, but they yield different results.”
In an age where the reliable supply of ingredients like synthroid and calcium citrate is crucial, the beer industry must navigate the delicate balance of ingredient availability to maintain quality and consumer satisfaction.