PurposeEnergy DIGESTER: RENEWABLE GREEN ENERGY

Posted on September 24, 2010 by Chet Layman, Senior Project Manager

In mid-2008, PC Construction was competitively selected by PurposeEnergy, Inc. as the design/build partner for a first-of-a-kind biogas facility project at the Magic Hat Brewery in South Burlington, Vermont. This unique project allows the owner, PurposeEnergy, Inc., to use the organic waste streams produced by New England’s largest craft brewery and generate biogas (a form of renewable natural gas). The biogas is then utilized by the brewery’s steam boilers and/or PurposeEnergy’s cogeneration plant. This brewery waste recovery system was developed by CEO and founder of the Arlington, Massachusetts based PurposeEnergy, Eric Fitch.  His vision was to use the by-product grains and yeast from breweries to make clean renewable energy.

Many of the specific details of the project are propriety, but the major components of the project include a Flow Equalization System, Mechanical Building to house the process equipment and piping, a patented Anaerobic Digester designed for brewery waste, and a Cogeneration System. After many months of estimating, value engineering, design, and going through the financing/permit process, construction began in late November 2009 with commission/start-up of the facility commencing in June 2010.

The brewery’s three waste streams; spent grain, high strength wastewater, and low strength wastewater (gray water), were previously disposed of through off-site trucking and surcharges at a local municipal waste treatment facility. Now these waste by-products are diverted to the anaerobic digester at the PurposeEnergy biogas facility. PurposeEnergy’s patented Biphase Orbicular Biodigester^TM, specifically designed for brewery by-products, enables the conversion of high solids content brewery waste into carbon neutral, renewable biogas.  Additionally, this system is designed to utilize the waste heat from the generator’s exhaust, coolant, and engine oil to heat the digester and preheat the water used in the brewing process.

The innovative technology in this project provides a number of benefits:

• By diverting the waste stream created during the brewing process, the brewery’s operating costs have been reduced as they no longer pay for waste treatment surcharges.  The brewery can also purchase the biogas directly produced from their by-products instead of purchasing natural gas imported from Canada.
• PurposeEnergy’s sound business plan makes this project financially viable. Not only is value created by converting the brewery waste stream into a clean, renewable energy, but the value of by-product remediation is also realized. This project is a “win-win” economic relationship for the brewery, PC Construction Company’s client, and the local community.
• The environmental benefits to the local community are numerous. The brewery no longer needs to truck its waste stream off-site thereby reducing traffic, noise, and air pollution. Using this innovative technology to convert spent grains and other by-products, creates a clean, carbon neutral energy source that decreases the effects of greenhouse gases on the environment and eases the dependency on fossil fuels. All-in-all, this enables the brewery to reduce its operating costs in a highly competitive marketplace, encourages the entrepreneurial spirit, and produces green renewable energy. True to PurposeEnergy’s trademarked slogan, “Saving the Earth. One beer at a time”.

With this facility, PC Construction Company and PurposeEnergy have helped a Vermont craft brewery and the environment by converting waste product to renewable green energy.

This project has been recognized as one of three finalists, and the only in the United States, for Power Engineering Magazine’s 2010 Projects of the Year Awards in the renewable/sustainable category.