Gills Onions, one of the nation's largest producers of fresh onions, peels up to one million pounds of onions per day, generating roughly 300,000 pounds of onion skins and trimmings. Prior to 2009, Gills Onions used a labor-intensive disposal method to spread the waste over nearby fields and leave it to decompose. This process led to the release of greenhouse gases and odors, attracted pests, and created the potential for groundwater contamination. Gills Onions investigated available waste-management practices and settled on anaerobic digestion as a potential solution, partnering with the University of California-Davis to tailor the available technology to onion trimmings. The result was the Advanced Energy Recovery System (AERS), which has been in operation at Gills Onions' Oxnard facility since July 2009 and handles 100 percent of the facility's onion waste. Within AERS, juice is pressed from onion peels and fed into an anaerobic digester to produce methane-rich biogas, while the remaining material is pressed into nutritive cattle feed. The biogas can be used in place of natural gas with some processing, and it has replaced 112,000 standard cubic feet of piped-in natural gas per day at the facility since 2009. The system provides 600 kilowatts of power - enough to fulfill 100 percent of the Oxnard facility's electricity base load (and equivalent to the electricity needed to power approximately 460 homes). The waste-to-energy system is a win-win for Gills Onions: it provides dependable, on-site power generation - crucial for a large facility that relies on constant refrigeration of fresh onions - and saves $700,000 annually in electrical costs and $400,000 in hauling disposal costs.
At Gills Onions, anaerobic digestion technology has transformed a waste management problem into profits. For its innovative approach to onion waste management, Gills Onions was awarded the 2009 Governor's Environmental and Economic Leadership Award (GEELA) (http://www.gillsonions.com/sites/default/files/geela_2009_award.pdf) and the 2010 Grand Conceptor Award by the American Council of Engineering Companies (ACEC). Gills Onions has been featured on Huell Howser's California Green (http://www.gillsonions.com/node/182) and on the Discovery Channel (http://www.gillsonions.com/node/272).
Brewing beer is messy: along with beer, the process yields spent grain, yeast, and wastewater. Breweries must pay - typically, by the pound - to transport their organic waste off-site to treatment facilities, or sell or give it away to farmers for animal feed. Anaerobic digestion technology provides another option - allowing breweries to convert their organics into energy that can be used on-site. To help breweries use their waste more sustainably, Eric Fitch, CEO of Arlington, MA-based PurposeEnergy, Inc., developed a new anaerobic digestion process tailored to high-solids organics from breweries. After a successful 2006 pilot project at Yuengling's brewery in Tampa, Florida, PurposeEnergy partnered with the Magic Hat Brewing Co., located in Burlington Vermont, to install an industrial-scale facility. PurposeEnergy pays Magic Hat $1/year to lease land adjacent to the brewery for its anaerobic digester. The company takes in Magic Hat's brewery waste and uses it to generate methane-rich biogas, which is converted into renewable electricity that is used within the brewery. The 492,000-gallon digester transforms brewery organics into 50 cubic feet of biogas per minute, generating 300 kilowatts of power, as well as heat to maintain the temperature of the bioreactors. Excess electricity is sold back to the grid. Magic Hat produces about 180,000 barrels of beer annually, and PurposeEnergy helps the brewery save $1.67 per barrel. The anaerobic digestion technology reduces the brewery's dependence on fossil fuels, takes the strain off of local wastewater systems, and productively recycles the brewery's organics to generate on-site power.
For its innovative approach to brewery organics management, PurposeEnergy has received numerous accolades. In 2010, it was selected by AlwaysOn as a GoingGreen Top 50 Winner on the criteria of innovation, market potential, commercialization, stakeholder value, and media buzz. In 2011, the company made Enterpreneur.com's annual list of 100 Brilliant Companies. Additionally, the PurposeEnergy facility at the Magic Hat Brewery was given an Honorable Mention for Renewable Project of the Year in 2010 (http://www.renewableenergyworld.com/rea/news/print/article/2010/12/power-engineering-names-renewable-projects-of-the-year).
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