Sierra Nevada taps waste-to-energy technologies as a way to close operational loops and demonstrate responsible brewing practices.
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.” […]”<