Sustainable Sours

Hermit Thrush Brewery in Vermont uses wood pellets to power its beer-making process.
By Patrick C. Miller | October 24, 2018

Combine numerous environmentally sustainable business practices, age-old brewing processes, the sourcing of locally grown ingredients, and unbridled enthusiasm for all of the above, and you have the core values of Brattleboro, Vermont-based Hermit Thrush Brewery.

Launched roughly four years ago as the brainchild of college buddies Christophe Gagné and Avery Schwenk, the goal was not only to produce a unique range of niche beers, but also to do it in an ethical manner. Part of the duo’s plan was to use sustainable, locally sourced wood energy derived from Vermont’s forests, dovetailing with the state’s push for greater use of advanced wood heating. “I believe that everybody needs to start doing everything they possibly can to help get the world off oil,” Gagné says. “But even if you exclude ethics and saving the Earth, oil is not going to go down in price. I don’t think the supply of oil will outstrip demand in the future. Rooting our costs and supply chain in locally sourced, renewable fuels is really a wise, long-term cash position as well. We do think of ethics first.”

Hermit Thrush Brewery purchased two oil-fired, low-pressure boilers for its brewing and clean-in-process operations, but they have never been fueled with oil. Instead, conversion pellet burners made by Pellergy were fitted on the boilers, along with a bin feed that holds about 500 pounds of wood pellets. Once the burner lights, a spring steel auger feeds pellets every 20 seconds through a flex hose, producing heat very similar to an oil-fired boiler. The Vermont-made system includes automated safety controls.

“What’s unique about Hermit Thrush Brewery is that they put in a unit that is a modified oil steam boiler, but added a bolt-on pellet combustor,” says Adam Sherman, consulting manager with the Biomass Energy Resource Center in Burlington, Vermont. “It gives a lot of flexibility to move to pellets without having to throw out your whole heat exchanger. You just take out the oil nozzle and clamp on the pellet combustor—using the heat exchanger of the pre-existing boiler. It’s a really cool option.”

Gagné says running two side-by-side boilers in tandem provides two heat options. “Our granularity of heat applications is not very high at the boilerplate,” he says. “What that means is occasionally, we have a little excess steam. So instead of just running the boiler kettle, we may need to use some of the excess steam to heat water for process cleaning needs in the hot liquor tank. It’s really just a matter of paying attention to your PSI gauges and modulating your steam valve a little bit.”

The brewery’s fuel is supplied by the Vermont Wood Pellet Co., which uses locally sourced wood from within an hour’s radius of Brattleboro. “It’s been consistently available and consistently of high quality,” Gagné says. “We use a standard softwood pellet. We prefer softwood because of the lower ash and we can clean out the boilers a little less frequently.”

The use of wood pellets has resulted in lower utility costs for the Hermit Thrush Brewery. The ability to purchase truckloads of wood pellets has also enabled it to modulate the supply chain at different times of the year. “We certainly haven’t had any large surprise bills coming from oil price fluctuations,” Gagné says. “Maybe the one drawback is that startup and shutdown times are longer when using a solid fuel like wood, as opposed to oil or gas. But with a few changes to our brewhouse methods in the first couple weeks of operations, it’s been pretty easy to manage. It takes a little more skill to brew on our system than it takes to brew on a typical equivalent system, but we’ve found that it’s worth it.”

Gagné says there are several reasons he and Schwenk chose to open a craft brewery in Vermont in general, and Brattleboro in particular. The state has legislation and tax incentives to support sustainable forestry. Plus, Vermont has a reputation as home to some of the nation’s best craft breweries. “There’s certainly a great beer community here,” Gagné notes. “We’re collaborating frequently and we’re sharing ideas. In an industry context where you have kind and fun people who are okay with sharing their best practices, I think you end up with a coalescing of good technicians that’s inspiring to other brewers.

According to the Brewers Association, Vermont’s 55 breweries ranks the state first in the U.S. with the number of breweries per capita. The state also ranks first in the nation with 18.9 gallons of beer brewed per adult over 21. The $309 million economic impact of Vermont’s breweries ranks second nationally on a per capita basis—generating just under $670 per person.

In addition, the association forecasts that the upward trend in U.S. craft breweries is expected to continue. A study by the organization shows another 2,500 to 3,000 new small and independent craft breweries will be added to the nearly 6,700 already in existence. In 2016, the U.S. craft brewing industry had a $67.8 billion economic impact and provided nearly a half million full-time jobs.

The Hermit Thrush Brewery specializes in barrel-aged beer, which Gagné says appeals to “beer nerds” and wine drinkers. This beer is aged for a year in oak barrels that have been previously used by local wine and spirt producers, adding a greater depth of flavor. The brewery also has a selection of kettle sour beers with broader appeal. “Those tend to be a little hoppier or lighter, depending on the beer,” he explains. “Because they’re not aged for a year, they’re at a little lower price point. Those are beers for the larger market rather than the niche barrel-aged sours.”

Because water is one of the main ingredients in beer, it was also a factor in the decision to locate Hermit Thrush Brewery in Vermont. “The water here is phenomenal and tastes great,” Gagné says. “Our water supplies are largely unpolluted mountain lakes and streams. It has a lovely, light mineral profile.”

And then there’s the wild yeast of Brattleboro, which corresponds with what Gagné calls his yeast-driven approach to brewing beer. He and Schwenk tested yeast at locations across Vermont before deciding they liked Brattleboro’s wild yeast best. “Yeast is a lovely fungus that’s carried by the wind,” he relates. “We are east of some very nice natural wilderness and the health of the native yeast is good here. Yeast feed on fruit and other sugar sources and sometimes grains. It helps to be in an area that has a significant wilderness component because you have more stuff in the wind.”

Most brewers formulate recipes aimed at reaching a certain flavor profile, but Gagné comes at it from a different direction. “I really love watching what wild yeast will do or wants to do and how it will behave in the end,” he explains. “And then I sort of backtrack and design a beer around that. Rather than saying the hops we use are the best hops you can find, it’s really more that we know how our yeast in this area behaves and ferments and how it tastes. We’re trying to make a beer that takes care of our yeast to taste the best and support the yeast-driven flavors as best it can.”

The beer from Hermit Thrush Brewery is distributed in Vermont, Massachusetts, Connecticut, New York and New Jersey. Another ethical decision of the brewery is to ship its beer in cans only. “We don’t do any bottles,” Gagné stresses. “We’re really trying to prioritize the environment. Cans are much more recyclable than glass. They are much lighter weight to ship. At every turn, we’re trying to minimize our fossil fuel footprint.”

 For now, Gagné and Schwenk are satisfied with Hermit Thrush Brewery’s beer remaining a regional product of New England. But if they decide to expand, Gagné says wood-fired boilers will be part of their future.

Author: Patrick C. Miller
Staff Writer, Biomass Magazine
[email protected]


Clearing the Air for More Biomass-Fired Breweries
   As a result of a Vermont clean air regulation, the environmental and economic benefits Hermit Thrush Brewery has achieved by using wood pellet-fired boilers is currently impractical for other breweries and commercial applications. “Boilers for breweries seems to be a perfect fit,” explains Pat Haller, an energy consultant with Efficiency  Vermont. “We’re kind of in a quandary right now. As a consequence of a state regulation, it has stopped the ability for other brewers that might be interested to put these retrofit burners on and have a pellet boiler system.”

    The problem stems from a regulation implemented by the Vermont Department of Environmental Conservation Air Quality Division, which unintentionally boxed out the option while attempting to close a loophole that enabled outdoor commercial wood pellet systems to be installed for residential use. Hermit Thrush Brewery installed its system before the regulation took effect.

       “Currently, the impractical part is that each boiler outfitted with a pellet burner would have to go through EPA air quality testing and that—for a one-off system—is too expensive,” Haller says. The cost of testing boilers that sell for around $20,000 would be in the tens of thousands of dollars, he says.
     Haller wasn’t aware the regulation existed until he began working with other craft brewers who were interested in using advanced wood heating. Their boilers would be in the 30 to 60 horsepower range, but the Vermont regulation applies to all boilers under 95 horsepower. “This 95 horsepower and lower regulation is preventing Vermonters—as well as a lot of people in the New England area—from being able to get an advanced wood heat boiler,” he adds.

      However, a fix is in the works that could be in place sometime in 2019. Haller says Vermont’s Air Quality Division has been provided data from testing conducted by Pellergy, which demonstrated that the amount of particulate emitted from its engineered systems was very low, and on par with a conventional boiler.

    “It was very promising from the state’s standpoint,” Haller says. “They could adopt some sort of standard that would be practical for companies to put in a boiler with a pellet conversion burner. They might be able to include in the rules a class of allowed systems because they’ve been tested and proven to have low emissions.”

   Another unintended victim of the regulation are Vermont’s maple sugar producers, who are interested in converting from oil-fired evaporators to wood-fired systems. “The Department of Environmental Quality didn’t even realize that their rules were boxing out evaporators in the state as well,” Haller says. “They’re very interested in trying to come up with a logical way of allowing them, but not diluting their intent on having high air quality in Vermont.”

     After all, what could be better for the state of Vermont than clean air, good beer and delicious maple sugar? “That’s the ideal, isn’t it?” Haller agrees.