Part of the solution

Brewing beer is a science that Ken Grossman, founder of Sierra Nevada Brewing Co., has perfected over the past 35 years. The craft beer pioneer has not only built a legacy that he plans to pass on to his children, he is also leaving a legacy of environmental stewardship which has much further reaching implications.

While consumers of Sierra Nevada’s various varieties are hopefully drinking responsibly, by producing energy from brewery wastewater, reclaiming heat, refining used cooking oil into biodiesel and composting organic waste, there is no doubt the company is brewing responsibly.

Mandi McKay, sustainability coordinator at Sierra Nevada, explains that since Sierra Nevada is a family oriented company, “We are able to do a lot of things that other companies might not be willing to consider.”
 

Biogas benefits

Sierra Nevada operates breweries in Chico, California, and in Mills River, North Carolina. While the Chico facility has been in operation since 1980, the Mills River brewery didn’t break ground until 2012. Both facilities operate anaerobic digesters for treating brewery effluent water. Each facility uses the biogas produced from the digesters a little bit differently. In Chico, the biogas is used to offset natural gas production for use in its boilers. The Mills River digester is also used in the boilers but is also being fed into two 200-kilowatt microturbines from Capstone of Chatsworth, California, which will generate electricity to power the operation.

McKay says the first anaerobic digester was installed in Chico in 2002, well before the technology had gained traction in the United States. The digester, manufactured by Veolia Water Technologies subsidiary Biothane, Pennsauken, New Jersey, is an upflow anaerobic sludge bed. The biogas produced from the digestion process is cleaned and treated by a biogas skid designed by Fuel Cell Energy, Danbury, Connecticut, before it is used in the boilers. When the digester was initially installed, Sierra Nevada had planned on using the biogas in its fuel cells, but the inconsistent flow of biogas from the digester was problematic for the fuel cells without a buffer zone.

“We just decided we would send the biogas all to the boilers because the boilers could definitely use it,” says McKay.

The fuel cells were installed in Chico in 2005 and are considered “old technology” by today’s standards, according to McKay. The company is currently deciding on a replacement for the fuel cells which is planned to be completed by the end of the year. Fuel cells, microturbines and other engine technologies have all been considered as potential replacements.

“Ideally we would like to produce electricity from any biogas we are producing at the wastewater treatment plant,” McKay says, adding, “It is fine to use in the boiler, but we would prefer to make electricity because it would be closing the loop a little bit better.”

Sierra Nevada put in a second digester in Chico, which was identical to the existing one about a year and a half ago. The digester in Mills River is from a different supplier. It was built by Symbiont, based in Milwaukee, and generates more biogas than the digesters in Chico because it can handle a higher solid content.

“We are able to send our spent yeast through the digester as well as our wastewater. That is providing more food for the digester and therefore producing more biogas,” McKay explains. “That is why we can power the boiler and microturbines in North Carolina. We are getting more bang for our buck in terms of digestion there.”

McKay says the Chico digester treats approximately 190,000 gallons per day of brewing wastewater and generates 1.5 million standard cubic feet per minute (SCFM) of biogas. McKay doesn’t have the exact numbers from the Mills River facility yet because the brewery is still in the commissioning stage. Currently, the new facility is brewing about a third of the beer that the Chico facility produces, and the restaurant is expected to open in March 2015.

According to McKay, Sierra Nevada benefits in several ways by treating wastewater on site. Not only does the company produce biogas, which has many uses, but it also has a cost savings. “For most brewing operations, if they are anywhere near our size, it makes economic sense to have a wastewater treatment plant on site,” she says. “Once you hit a certain number of barrels per year, you are generating so much wastewater that it puts a high demand on the local municipal treatment plant.”

Municipal wastewater treatment plants charge higher “brewery rates” to treat the water because it still has a lot of biological activity in it and places a burden on the plant. “It makes sense for breweries to pretreat their water because they don’t get charged those brewery effluent rates and they can benefit from it like we are. They get free fuel to power their brewing process,” says McKay.
 

Taking some heat

Sierra Nevada tries to capture and recover heat wherever possible. “Pretty much any time we have heat leaving a process, whether it is from the kettles or from a boiler or cooling down wort, we are capturing that waste heat,” McKay says.

The company uses heat exchangers, condensers and steam boilers to capture heat. “Heat is a resource to breweries. We need a lot of heat energy to do what we do to make beer,” McKay notes. “Any time we have waste heat coming off of anything, we try to recycle it.”

One of the ways the company recycles heat is from the fuel cells. “We have hydrogen fuel cells on site that are generating electricity by using natural gas, but they operate at a really high temperature so we are able to capture that exhaust heat that is leaving those fuel cells, turn that into steam and send that steam into the brewing process,” explains McKay. She adds that heat loops like this are widespread throughout both breweries.
 

Going further

Sierra Nevada does not stop its closed-loop processes at just heat and water. It actually produces biodiesel from the used cooking oil generated at its on-site restaurant in Chico. The oil is collected and then converted into biodiesel using an on-site processor from Springboard Biodiesel also based in Chico. McKay estimates the company produces about 300 gallons of biodiesel per month which is used in the company’s long-haul and route trucks to offset diesel consumption. At a production price of about $1.70 per gallon, McKay says it saves the company on fuel costs as well as the cost of oil disposing.

In addition to producing heat, electricity and fuel from waste generated at its breweries, the company began composting about four years ago. All pre- and post-consumer food, spent hops and grains, used paper towels and grass clippings go into a fully enclosed composting machine. The HotRot composting system, designed and built by HotRot Composting Solutions based in New Zealand, is one of only two systems in the U.S. The organic material is enclosed in the vessel for about 10 to 12 days. When the compost comes out of the vessel, it is placed in a field for about a month before it is ready for use. Sierra Nevada uses the compost in its restaurant garden and in its barley and hops fields.

“I feel like composting gets overlooked in the world of greenhouse gas mitigation,” McKay says. “Composting is one of the most effective ways we can mitigate climate change because we are keeping organics out of the landfill where they would otherwise generate methane.”

McKay says the company does its own composting in Chico because there was not a nearby facility for the material. “It is something we decided to do despite the payback being about 15 years. It still made sense for us to do it because otherwise we would be sending waste to the landfill and we just didn’t want to do that,” she says. The company produces about 75 yards of compost per month in Chico. In Mills River, rather than make compost and biodiesel on site, the brewery has partnered with local companies to process its organics and used cooking oil.

According to McKay, Sierra Nevada has an overall solid waste diversion rate of 99.8 percent.

McKay, who has worked as sustainability coordinator at Sierra Nevada for six and a half years, knows there is something special about Sierra Nevada that goes beyond the beer selection. “I feel very fortunate to work for a company that truly understands these issues and understands that businesses can be part of the solution to a lot of the environmental issues we face,” she says. “Ken and Sierra Nevada have definitely been a leader in this industry in both ways. They’ve been a craft beer pioneer and a sustainability pioneer.”

The author is managing editor of Renewable Energy from Waste and can be reached at ksmith@gie.net.

Mandi McKay, sustainability coordinator for Chico, California-based Sierra Nevada Brewing Co., talks to Renewable Energy from Waste Managing Editor Kristin Smith about the processes the company employs in its operations to use waste as a resource. Watch the video at
www.REWmag.com/rew-2014-mckay-sierra-nevada-video.aspx.