PurposeEnergy is eyeing the brewery industry for its novel AD cogen system.
By Lisa Gibson | September 20, 2011

PurposeEnergy Inc.’s Biphase Orbicular Biodigester, or BOB for short, is ideally suited to process waste streams with more solids than traditional anaerobic digesters. With that capability in mind, the company is focusing on the brewery market, and its waste streams such as spent grains.

“The system we’ve developed is specifically designed for high-solids waste,” says Eric Fitch, PurposeEnergy founder. The novel system combines three types of digesters into one process, Fitch says, declining to divulge details of those three components.

The first digester breaks down the waste stream into soluble elements, which then are sent through the second two reactors. The first commercial system is currently operating at Magic Hat Brewery in Burlington, Vt., processing 500,000 gallons, Fitch says. It began in July of 2010, shutdown when the brewery shut down over the holiday season, and started up again in June.  During that shut-down period, PurposeEnergy made upgrades to BOB from what operators had learned, including replacing a pump that would frequently get plugged up from the spent grains, according to Fitch. He adds that the cleaning process was time consuming and messy.

“These things happen when you build a plant like this,” he says. “There’s probably a million pieces involved. You kind of throw things at the wall and see what sticks.”

The system produces 330 kilowatts of power for the brewery, as well as steam for its boilers, or to control the temperature of the bioreactor during cold Vermont winters, Fitch says. “The brewery process is very steam-intensive,” he says, adding that the biogas replaces the need to purchase natural gas.
BOB was designed with breweries in mind and Fitch says PurposeEnergy has a few projects in the pipeline, declining to release a timeline or location for startup of the next installation. “We have a competitive advantage when it comes to solids, and breweries have the same solids problem around the world.” He adds, though, that a number of other industries have inquired about BOB, presenting additional interesting applications.

—Lisa Gibson