Proving the Biobrewery Concept

Two European companies have an anaerobic digestion process they say works perfectly for brewery residues, but convincing a centuries-old industry to change its operations poses a problem in marketing and widely implementing the practice.
By Lisa Gibson
The Bavarian State Brewery Weihenstephan is renowned in the beer industry, making its Freising, Germany, location perfect for demonstrating an anaerobic digestion (AD) process for spent grains and yeast waste streams. "Everybody who works in this field knows Weihenstephan," says Markus Grasmug, chief technology officer for Austria-based enbasys gmbh, developer of the biogas process employed at the facility.

Indeed the location did help draw attention from all over the world including the United States. Enbasys' multifeedstock Enbaferm process was coupled with a hydrolysis system developed together with ATRES engineering biogas, a German company. The demonstration was not an attempt to prove the technologies, as they have already been deemed successful, but instead to show breweries that their waste streams can be used to produce energy for their own processes. "We know that with our technology, we can produce biogas, but to convince them, to see with their own eyes that, yes, I can produce biogas from my feedstock, is why we installed the demonstration plant," Grasmug says.

"The idea from this demonstration plant was to show that our concept for using the spent grains from breweries for anaerobic digestion is a feasible project or a feasible idea," says ATRES Owner Gunther Pesta, who has been working on the concept for more than 10 years.

The Technology

The patented Enbaferm system consists of two phases: hydrolysis and methane, according to Grasmug. The process is being used at several locations with multiple feedstocks including organic portions of municipal solid waste. The only difference is the pretreatment for the different feedstocks. Enbaferm has a higher loading rate than conventional AD systems, making only two fermentors necessary, regardless of the volume of feedstock. "That means we can load three times more organics into the system with the same efficiency," Grasmug explains.

Enbasys engineers were able to design the system to eliminate the problem of foaming in the fermentors, along with sediment settlement. Sediment accumulation means money and time spent on discharging, cleaning, refilling and restarting the fermentors, Grasmug says. Enbaferm also saves its owners and operators money because it requires no chemical additives. "A lot of systems need to blend the feedstock with other substrates to stabilize the process or for pH regulation," he says, adding that the cost of transporting those chemicals to the plant can be burdensome.

On the other hand, the hydrolyser is a simple and ordinary process, Pesta says. "It's just less or more a simple hydrolyser similar to other biogas processes," he says. The system is smaller than others, however, has an optimized retention time and special procedural methods.

When integrated at the 1,000-year-old Weihenstephan brewery, the two processes were just as efficient as their developers had hoped. "It was very successful," Grasmug says of the demonstration. "We had a lot of voices, even from the United States." The demonstration was installed and operating for nine months, ending in late March/early April of this year and producing small amounts of biogas. "We didn't heat the whole city with the energy," Grasmug jokes, adding that the demonstration biogas, as it was in such small quantities, was not used for energy.

"If you install this system at a commercial scale at a brewery, you can use this energy, this biogas, for your own process," he says. Between 4 and 5 liters of heating oil is required to produce 100 liters of beer. "If you use that residue coming from your process, you can substitute about 50 percent of this fossil energy," he says. The system is applicable at any brewery in the world, both companies say, but as with any new process there are barriers to its widespread implementation.

Starting the First One

"The main challenge is to convince the brewery to install biogas," Grasmug says. "In their minds, anaerobic digestion is always linked to agriculture." The beer production industry is old and in many cases conservative, he says, so it is difficult to persuade companies to make such a big change.

"The thing is, one brewery has to start, just like in any business," Grasmug says. That first brewery installation might be just around the corner at Heineken's Gösser Brewery in Austria. If all goes well, the system could be operational next year, although Grasmug says 1,000 things could hinder development. "They should become the showcase plant to install such a process," he says.

But even after convincing breweries of the system's effectiveness, there's another obstacle. Spent grains can be sold to the agriculture industry as animal feed for anywhere from €7 to €15 ($9 to $18) per metric ton, creating Enbaferm's only competitor. Installing a biogas process does not always represent monetary gains for breweries as it might for other types of clients, but does help to build their reputations as green companies, Grasmug says. "It's more for marketing," he says. "A sign that they are doing something for environmental prevention; that they don't use fossil energy."

Several breweries have approached enbasys and ATRES with interest in Enbaferm, albeit with reservations. "They do come to us," Grasmug says. "They're interested in the technology, but they have a lot of fear because no plant worldwide is installed for that kind of feedstock."

Breweries have three main feedstock streams: spent grains, the water used for cleaning in the process and yeast, according to Grasmug. About 70 percent of breweries around the globe have AD systems for the wastewater. "But worldwide, there are no plants producing biogas from the other two streams: spent grain and yeast," Grasmug explains. "Our technology fits perfect for these two streams."

Weihenstephan was satisfied with the outcome of the demonstration, and in fact, it's still installed there, Grasmug says, but site restraints pose a problem for commercial installation. The plant has expressed no interest in scaling up for that reason, along with the fact that it's government-owned and therefore is not suffering from financial stress, he says. In addition, the brewery is a relatively small operation.

Focus on Feasibility

Enbaferm represents significant benefits to any brewery, Pesta says, ensuring stable treatment of residues and the possibility of producing energy for a cost savings, not to mention the benefit of using less fossil fuels. By digesting the residues, breweries are not at the mercy of volatile market prices for spent grains.

The companies have done between 10 and 15 feasibility studies, Pesta says, which evaluate each individual site, wastewater treatment and chemical oxygen demand. They also conduct a review of the infrastructure and income from spent grain sales, along with payments for wastewater. The return on investment for a biogas process depends partially on what the company pays for energy, he adds. "To see the feasibility or find out if it's an economically reliable system, you need to have already looked at the internities," Pesta says, listing biogas use, what kind of treatment the process will need at the back end and whether the operation would be cheaper with biogas. That framework makes up about 60 percent of the economic feasibility study and Pesta cautions that it's crucial to evaluate before installation. "It's really necessary to have a really great effort on the basic engineering and basic calculating," he says. "It takes a little bit more time and is a little more expensive than doing it the easy way, but at least you're saving a lot of money because when later you find out that it's not feasible or have a change in the facility, the more expensive it gets after."

"The most important thing is to provide them with the best conditions," Grasmug says. "What they need to be very effective."

The next demonstration of Enbaferm will be at a slaughterhouse, Grasmug says, and he expects positive results there, too. "The biogas facility as it was demonstrated in Weihenstephan is certainly a special technology and very interesting, but you can build this biogas plant anywhere," Pesta says.

A brewery in Korea is contemplating installation of the process, according to Grasmug, and several others could be on the verge after seeing the Weihenstephan demonstration. "The idea of Weihenstephan was just to say, ‘OK, we have the technology and we can show feasible results with that kind of substrate,'" Pesta says.

Lisa Gibson is a Biomass Magazine associate editor. Reach her at or (701) 738-4952.