Sustainable Energy: Drink to That
The mash filter at Alaska Brewing Co. reduces the moisture content of spent grain, enabling the waste to be burned as fuel.
Alaska Brewing Co.
Of all the mystic powers that its drinkers have ascribed to beer, few would claim that it cleans the environment. Fewer would count three different ways of cleaning the environment. Geoff Larson, president of Alaskan Brewing Company, is one of those few.
More Bang for the Brew
Larson’s brewery in Juneau is already demonstrating the first way by burning spent grain in its boiler. “We all create waste,” Larson said at the Alaska Sustainable Energy Conference in Anchorage, “but how do you look at it differently?”
Larson, a chemical engineer by training, figured the economics of transporting fuel and ingredients to Juneau, as well as the scale of his operation, could make waste-to-energy pencil out. He notes that Heineken and its subsidiary, Scottish & Newcastle UK, had invested heavily in burning spent grain, but those projects didn’t pay off.
Alaskan Brewing, though, has made it work since 2012, fueling its steam boiler entirely with spent grain, reducing the company’s overall fossil fuel consumption by half. “We still have some fossil fuel use,” Larson says, “but we used the spent grain to augment, and we did it profitably.” That’s a net positive for greenhouse gas emissions, since living biomass would’ve released carbon dioxide as it decayed anyway, whereas fossil fuels sequestered underground for eons release new carbon into the atmosphere when burned.
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Alaskan Brewing used to send its used-up grain to a farm in Washington as fodder for dairy cows. “Sometimes what has always been done by others—agricultural use—is so easy that you ignore a better solution,” Larson says.
Further experimentation on waste-to-energy at the brewery has resulted in four patents, with three more pending. The latest patent points to the way to a new application—a second way to clean the environment.
Larson says the US Patent and Trademark Office notified him two weeks before the conference that one of his patents could be used to destroy PFAS, a class of chemicals also known as per- and polyfluoroalkyl substances.
As useful as PFAS can be for a wide variety of applications, their residues have been associated with toxic effects and, what’s worse, the molecules are very stable. PFAS don’t naturally degrade and can accumulate in the food chain. One way to destroy PFAS is to burn them at 2,500°F, which requires a large energy input and is near the melting point of stainless steel.
While adjusting various factors in its waste-to-energy process, Larson says Alaskan Brewing found a way to mimic the atmosphere of 2,500°F combustion at 1,600°F to 1,800°F, thus making PFAS destruction more practical and efficient. “To what degree? We don’t know, but we know the chemistry is there to do it,” Larson says.
A Bonus Pollution Solution
Mechanical screens at Juneau’s wastewater treatment plants filter out non-biodegradable debris, resulting in smoother biosolids entering the dryer.
City and Borough of Juneau
In addition to being a chemical engineer and beer magnate, Larson also serves on Juneau’s municipal Utilities Advisory Board. In that role, he’s been keeping an eye on a problem with the city’s wastewater.
The problem is that treated sewage leaves behind biosolids, and Juneau has nowhere to put them. The incinerator that used to reduce biosolids to ash was retired in 2010 due to age. A local landfill stopped accepting the smelly, black sludge due to its odor. Since 2012, the city has filled shipping containers and had the waste barged to a landfill in Oregon.
The removal option costs the City and Borough of Juneau about $1.4 million each year. While Larson was in Anchorage for the conference, the Assembly was considering whether to spend $2.5 million on crushing equipment to squeeze the biosolids, packing more mass into the fleet of forty-five watertight shipping containers.
In 2016, Juneau spent $16 million on different equipment to treat the biosolids: a dryer. That facility went online in 2019, and city officials hoped the dried material could stay in town as a soil amendment—that is, fertilizer. However, PFAS prevented that. The chemicals pass through human waste and accumulate in the biosolids, so environmental regulators do not allow contaminated biosolids to be returned to the soil.
Now Larson sees the accumulation of PFAS in biosolids as an advantage. “The PFAS that we have a hold of is ours to deal with,” he says. With his newly patented combustion process, Juneau might have a way to decontaminate its waste, generate energy, and avoid the expense of transporting sewage south.
Like spent grain, Larson says, biosolids are about 30 percent protein and have an energy content of 9,000 British thermal units per dry pound. He suggests that Juneau launch a pilot project to burn the dried biosolids as fuel. “This is a bit of a miracle,” he says, “to think that in our backyard we’re able to capture PFAS, and we can take a waste stream that’s high protein and deal with it. We can disrupt the ecosystem of PFAS.”
Thus, the third way the brewery can clean the environment is to solve Juneau’s biosolids problem and, as a bonus, secure a cheap, inexhaustible fuel supply.
As he wrapped up his presentation to the conference panel, Larson shared a bit of Alaskan Brewing Company’s philosophy: “Kudos to people that try because that’s what’s going to advance our abilities to be nurturing in our place in the world.”
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