Barrels of Biogas
There has never been a prohibition against innovation. Breweries, distilleries and related industries are using biomass and waste to produce renewable energy.
Founded in 1986, Abita Brewing says it is the 30th largest commercial brewer in the nation. In 2008, the company expected to exceed 85,000 barrels of production and $16.5 million in revenue.
Beer is brewed by first milling malted barley into grist to expose starches in the grain. The grist is then mixed with warm water to make mash. Enzymes in the mash convert starches to sugars. Sugary wort is then drained and the leftover mash is sprayed with hot water to sparge the remaining wort from the mash. The wort is then boiled with hops and run through a whirlpool to remove solid proteins and hops fibers. The wort is then cooled and fermented into beer using yeast. As the beer ages, the yeast settles and is drained off. Finally, the beer is filtered to produce a finished product.
During the brewing process, anything that isn't put into a keg or bottled is considered waste, including spent grain, spent hops, sugars, proteins and yeast. "We have a lot of yeast because we make a lot more yeast than we can use," Blossman says. Specialty brews that rely on raspberry puree or strawberry juice for flavor also produce waste from those ingredients. "And when we're filtering and filling, we lose actual beer, too," he says. But one man's trash is another man's treasure, which is why Abita Brewing is turning waste into energy.
A portion of the waste Abita Brewing produces is turned into energy in the form of animal feed. Proteins from the brewery waste are mixed with spent grains and sold to a local dairy farmer. The rest "goes down the drain," Blossman says, but not into a sewer. Instead, the waste is fed to a 570,000-gallon Siemens Water Technologies anaerobic digester, which can convert 75,000 gallons of brewery waste per day into biogas. The methane-rich gas is then fed to the brewery's boiler, displacing the need for fossil fuel natural gas. Installed in April 2008, the system currently processes 45,000 gallons of brewery waste per day and produces 490 million cubic feet of biogas each month.
Blossman says he is pleased with how well the digester works. "So far, we have been very successful in the quality of the gas," he says. "We have tested it three or four times and every time it shows us that we have about 92 percent methane, which is incredible. We have a very clean gas." Blossman notes that biogas can be very corrosive. "Ours isn't, but we still go through the steps of drying it and putting it through an iron sponge, which is designed to take out any of the natural acids that are in the gas, which keeps it from pitting the steel of our boilers," he says.
Prior to installing the digester, Abita Brewing used an aerobic system to treat wastewater, Blossman says. "It was a good system and it worked," he says, "but we were outgrowing the system pretty quickly, and so we needed to add capacity. And when we decided to add capacity, we decided to change technologies and go to an anaerobic system."
Besides being able to capture and use biogas, moving to an anaerobic digester has provided Abita Brewing with additional benefits: the system requires less manpower, less energy and it smells better, too.
"In an aerobic system, you have a population of bugs that actually grow a lot more," Blossman says. "It's like yeast, it keeps growing and growing and you have to constantly take solids out of the system and dewater them, whereas in the anaerobic system, you don't have nearly the growth of the bugs.
"The other thing is that it requires a lot less energy," he says. "The aerobic system had these huge air blowers to stimulate the aerobic bacteria and that required energy.
"And I like the fact that it is totally sealed and we have an odor recovery system, and so we're better neighbors now," he says. "When an aerobic system is operating perfectly, you won't have much of a smell, but inevitably you do-I know from experience that you do-whereas with this system, we haven't had one complaint from a neighbor. You just don't smell it, because everything is enclosed. Anything that you're losing, you don't want to lose, because that's gas and you want to keep it."
Switching from an aerobic to an anaerobic treatment system wasn't cheap. Blossman says the anaerobic digester cost Abita approximately $1.5 million, whereas a similar-sized aerobic system would have been $900,000 or less. "But in the long run, we thought it was a better fit for us," Blossman says. "We liked the idea of using our own gas. We try to be as green as we can around here and we have had the luxury of being in business for 23 years and so we can do these kinds of things. If we had tried to do it 15 or 20 years ago, we wouldn't have had the resources to do it. But now, we don't have to be as picky about our payback."
Breweries aren't the only ones recycling waste for energy. Distilleries, too, are producing energy along with spirits. Bacardi Limited, which has 31 plants around the world, makes Bacardi rum, Grey Goose vodka, Dewar's blended scotch whiskey, Bombay Sapphire gin, Cazadores tequila and more. The company also produces energy. According to Stephen Harvey, global environment, health and safety director for Bacardi, the company has patented its own technology for using anaerobic digestion to treat rum distillery wastewater and to produce energy from biogas. The company has licensed its technology to several other companies, including Cervecería India Inc. in Puerto Rico and Brugal & Co., C. por A. in Santo Domingo.
Harvey says the company's first anaerobic digester was commissioned in 1982 at Bacardi's largest distillery in Cataño, Puerto Rico, with additional digesters built in 1992, 2000 and 2003. The system, engineered by Black & Veatch Holding Co., treats 1.2 million gallons of still bottoms, unfermented molasses and water from the distillery each day and has the capacity to treat 2 million. The 7 million cubic meters of biogas produced annually is fed to boilers to make steam, which is used in the distillery to make rum.
"Last year, the Cataño plant derived more than 30 percent of its energy requirements from naturally created biogas," Harvey says. "[We] avoided consuming more than 5 million liters of nonrenewable fuel oil, which would have generated more than 16,000 metric tons of CO2. The distillery is currently investing nearly $7 million to build a cogeneration facility, which will produce electricity from the biogas, to further enhance the site's energy efficiency and lower its carbon footprint."
Another Bacardi facility that uses anaerobic digestion is the Martini & Rossi plant in Pessione, Italy, near Turin, which produces 12 million cases per year and is Bacardi's largest bottling operation. Harvey says the system, which was engineered by Biotechnical Processes International Ltd., was commissioned in 1998 to treat wastewater produced during blending, filtration, clarification and bottling operations, mostly from washing equipment. The wastewater contains sugars, vermouth, alcohol and other dissolved organics. The system treats 200,000 gallons per day at capacity. The 180,000 cubic meters of biogas produced annually is fed to a cogeneration facility that produces electricity and hot water.
The electricity powers the wastewater treatment system and also the production area. The hot water supplies 50 percent of the heat for the treatment system.
Overall, the Martini & Rossi operation is renewable intensive, where "92.5 percent of operational waste is recycled," Harvey says, "including solids such as paper, wood, glass, cartons, metal and plastic."
A third Bacardi facility with an anaerobic digester is Gemini Distillers, a Bacardi partner, in Nanjangud, India. Gemini supplies alcohol to Bacardi, and Bacardi owns and operates a distillation unit there to produce rum. The anaerobic digester was commissioned in 1990 to treat 110,000 gallons of still bottoms per day, with capacity to treat 130,000. The 3 million cubic meters of biogas produced annually is burned to generate high-pressure steam to power a turbine to generate 90 percent of the distillery's electricity. Exhaust steam is used to distill rum. The system originally was a fixed-film, random media technology built by Shakthi Sugars Ltd., later changed to an arranged media technology built by Lars Enviro Pvt. Ltd.
"All three sites benefit from deriving a stable source of energy from what would otherwise be a waste stream," Harvey says. "Biogas is a sustainable form of renewable energy that helps Bacardi reduce its carbon footprint with the added benefit of providing the sites cost stability at a time when fossil fuel prices have seen considerable fluctuation."
Ryan C. Christiansen is a Biomass Magazine staff writer. Reach him at firstname.lastname@example.org or (701) 373-8042.