Keeping Cool: As Barrel-Aging Trends Up, Brewers Go Below

June 25, 2018 By Daniel Hartis

Founders Brewing Co. has undergone several expansions in Grand Rapids over the last two decades, both at its original brewery and taproom as well as at a new facility that specializes in barrel-aged beers. The brewery’s progress has been easy to see for locals and tourists visiting the city, but one of its biggest areas of expansion is hidden from public view.

About three miles away from the brewery, and far below the streets of Grand Rapids, 14,000 barrels of beer quietly age.

The barrels are located in former gypsum mines once owned by the Alabastine Mining Company, and now by Michigan Natural Storage. The mines maintain a steady temperature of 50 degrees Fahrenheit or lower, which makes them ideal for storing a number of products—especially beer.

“The level that we’re on, we’re 85 feet below the surface of the earth and it’s about 38 million years old,” says brewery co-founder Dave Engbers. “I asked if they found fossils or stuff like that, and they said where we were predates any living organisms. The ceiling is under an old lake bed.”

The brewery stored its first barrels in the mines around 2004 or 2005, estimates Engbers. Founders had started aging beers in barrels just a few years before, and soon after the barrels were taking up space at the brewery that needed to be used for additional fermentation capacity.

Engbers and co-founder Mike Stevens had a friend at Michigan Natural Storage who proposed aging barrels there, which made a lot of sense given the facility’s proximity to the Grand Rapids brewery. Now, some of the brewery’s most well-known beers—like KBS and Backwoods Bastard—spend time maturing in the mines.

The underground aging program at Founders may be novel, but aging beer underground is nothing new. Whether manmade or natural, more brewers are going underground with their barrel-aging programs.

A Return to Tradition

In the days before refrigeration, brewers—especially those specializing in lagers, which ferment at lower temperatures than ales—sought out underground spaces to age their beers. It was a common practice at breweries across Europe, and when German immigrants built breweries in the United States, many of them looked for underground cellars that could provide the cooler temperatures needed.

August Schell was one such brewer. Schell left Germany for the United States in 1848, and in 1860 built the Schell’s Brewery in New Ulm, Minnesota. Schell had cavernous cellars beneath the brewery dug out, creating a space to store barrels of the brewery’s lager.

Jace Marti remembers cleaning out the caves as a boy—and not fondly.

“I think that was one of those things that my dad did a little as punishment, but also as an initiation thing,” recalls Marti with a laugh. “There was no light down there, it was terrifying as a kid.”

Now, as a sixth-generation brewmaster at August Schell Brewing Co., he uses the caves to age his own beers. In 2015, the brewery reopened the caves, where currently 55-56 bourbon barrels reside.

True to the brewery’s heritage, these barrels almost always contain lagers of some kind—though they are quite different from the styles August Schell brewed so many years before. The base beers, says Marti, sometimes don’t fit neatly into style guidelines, but usually they are a “big, malty lager in the 10 percent range.”

The caves typically stay in the upper 30 degrees in the winter, and can reach 50 degrees in the summer. Marti says that the differences in temperature between the seasons imparts differences in the character of the beers—namely, that in the summer months the warmer temperatures help extract more flavor from the barrels.

“I think what we’re trying to achieve is more than a standard lager beer,” says Marti. “Having some variations in temperature is good for what we’re doing. A lot of the yeast is pretty much gone, and now we’re just trying to pick up residual spirit character and barrel character. It’s very different than what we were trying to accomplish 100 years ago.”

The Challenges of Aging Underground

Having access to a subterranean space, while rare, is just the beginning for breweries wishing to age underground. The unpaved floors, jagged walls and inconsistent dimensions of these spaces often necessitate a more labor-intensive process than simply storing barrels in a warehouse.

Michigan Natural Storage renovated its gypsum mines with elevators and concrete floors, but getting barrels to the facility still requires a lot of work from Founders.

“The barrels are on racks so they get unloaded from our facility, then brought over to their facility,” says Engbers. “And then they’ve got two industrial elevators. All of that adds to the cost and the labor.”

But at least Engbers has forklifts, and racks on which to store the barrels. The caves at August Schell Brewing Co. aren’t as accommodating.

“It’s a monumental pain,” says Marti. “We have to use different sections of the cave. We take half of the barrels in from one entrance, and the other half through another.”

Laborious though that that process is, work was much harder for the generations of brewers that came before Marti. In the late 19th century, teams would cut ice blocks from the nearby Cottonwood River and pull them by horse up the hill and into the cellars, where the ice would help maintain the necessary temperatures to lager the beers through warmer months.

Marti’s brother tried to replicate the experience once, pulling the old ice tong’s right off the wall of the brewery’s museum. He went down to the river with a chainsaw and lugged a block into the cellars, only to see it melt in a matter of days.

“We won’t be doing that again,” says Marti.

And, of course, another challenge when it comes to aging underground is having the space in the first place. Not every brewery is located miles away from mines that go far below the Earth’s surface, or above cavernous cellars.

At Santa Fe Brewing Co., founder Brian Lock decided to make his own underground cellars, though “underground” here is used a little more loosely.

“They’re not very far underground, they’re inside a bermed hill that they’re put up against,” says Lock. “But they do get a lot of the thermal consistency from being underground. The temperatures are pretty stable, which is great for barrel aging beer.”

Lock had six shipping containers leftover after building his taproom in Albuquerque, and wanted to put them to good use at the Santa Fe location. So they dug out the hill and placed the containers on concrete footings, then sprayed insulation and backfilled around the containers.

The brewery is located in the high desert, notes Lock, but with an elevation of 7,000 feet it’s cooler than many people realize. The six 40-feet-long containers stay at a pretty consistent 60-65 degrees Fahrenheit in the summer. In the winter, the brewery uses space heaters to ensure the containers don’t get too cold.

The underground portion is used to age the brewery’s sour beers, and there’s a small tasting room for sampling. In the future, says Lock, there will be a cave bar that the brewery will open up for special occasions.

The Future is Dark

Despite the challenges that come with aging beers underground, there are breweries eager to carry on the tradition. Earthbound Beer opened last year in St. Louis, Missouri, a city that is no stranger to underground cellars; Anheuser-Busch and Lemp Brewery both were built above the tunnels of a natural cave system. Earthbound inherited cellars of its own, as it now occupies the former Cherokee Brewery space. While the nascent brewery has but a few barrels stowed away at the moment, the owners do have plans to expand their cellars (with the possibility of bringing a foeder and coolship below as well).

Even breweries that don’t have natural caves running below the property are experimenting with underground aging. Brewery Ommegang of Cooperstown, New York, once stowed away Hennepin and other beers in Howe Caverns of upstate New York. Though the brewery no longer ages beer at the caverns, the partnership could serve to inspire other breweries.

Wabasha Brewing Co. is located less than half a mile from the Wabasha Street Caves in St. Paul, Minnesota, and actually produces a beer by the name of Cave Stout, with imperial and bourbon-barrel-aged variants. The plan has always been to age that beer in the nearby the caves, says co-founder and head brewer Brett Erickson. While he has received permission to do so from the caves, Erickson wants to wait until the brewery’s barrel-aging program has grown before moving any production.

And even though Founders has an astonishing 14,000 barrels of beer aging in the former gypsum mines, there may even be room there for a few more players.

“This was kind of our little secret after a while,” says Engbers. “Then the word got out and next thing you know there’s a couple other breweries that store stuff down here.”

For Engbers, it might be easy enough to store thousands of barrels beneath the streets of Grand Rapids. Hiding them is another thing altogether.

Daniel Hartis is the editor of All About Beer Magazine.