Cheese Producer Reduces Power Costs With Microturbine
Pearl Valley Cheese in Fresno is using biogas produced from treating its cheese wastewater in an anaerobic digester to generate electricity, which will generate significant savings from energy costs, according to Pearl Valley President Chuck Ellis. Pearl Valley Cheese (PVC) manufactures 25,000 pounds/day of natural cheeses that are distributed throughout the eastern United States. The company’s 40,000-square foot operation houses a retail store, administrative offices, cold storage warehousing and manufacturing facilities. In business since the 1920s, PVC had always disposed of its wastewater on the family’s farm. As cheese production increased, so did the volume of wastewater. In 2008, the Environmental Protection Agency “insisted that we make considerations for a new disposal plan,” says Ellis.
Construction of the facility began in 2009 to handle the cheese-making operation discharge of about 40,000 gallons/day of wastewater. Siemens Water Technology designed and built the digester. The system also includes two Dissolved Air Flotation (DAF) units to remove solids, and a biogas storage vessel. PVC’s original plan had been to use a digester to produce biogas to fuel the facility’s boilers. Then the price of natural gas dropped, along with the potential savings from using biogas, Ellis says. He learned about microturbine technology, which would reduce power costs, and last September, purchased a Capstone Micro Turbine, custom-designed and installed by Walbridge, Ohio-based GEM Energy. GEM also installed a high-pressure system to remove moisture from the gas. The turbine began producing electricity in March 2013, and “has worked out very well,” Ellis says, adding that some issues had to be resolved relating to gas supply to the turbine. The company has a net-metering arrangement with its local utility, Frontier Power Co., to feed the power it doesn't use on-site into the local electrical grid.
The solids, a by-product of cheese production, are collected in a sludge holding tank for land application. The solids are rich in phosphorous and nitrogen and have significant fertilizer value for the crops grown near the cheese plant and on the family farm, Ellis explains. The company has also installed a dewatering system to help facilitate land application. -- Adapted from Biocycle Magazine Article published in May 2013
In March 2014, the company purchased an additional Capstone Microturbine to utilize biogas that was being flared off as excess wasted gas. The new unit is connected to the electrical supply panel in the wastewater plant’s electrical control room. It is anticipated that it will supply about 50% of the electricity for the wastewater plant. The company believes that sustainable practices for the company’s wastewater are not only good for the local environment but are also economically beneficial with this technology.
See the Siemens diagram below to better understand our cheese making process and byproducts.