Fremont, Michigan Community Anaerobic Digester
The Fremont Community Digester plant, located in Fremont, Michigan, processes more than 100,000 tons of food waste annually to produce biogas, electricity, and soil amendment. This system was developed by NOVI Energy and uses a complete mix anaerobic wet digester that can efficiently process a variety of feedstock. Three one-million-gallon digester tanks accept waste from a wide variety of sources, including food industry processing waste, dairy products, ethanol production byproducts, and industrial glycerin and alcohols, and process these materials over an approximate 22-day period in an oxygen-free environment. Local companies such as Gerber and McDonald's contribute waste to the digester, providing them with an effective way to manage their production waste. The developer has been able to secure 20- or 30-year contracts with some source-separated organics providers, ensuring sustainability of the facility over the long-term. This wet digester system can switch between thermophilic (115-160 degrees Fahrenheit) and mesophilic (86-104 degrees Fahrenheit) processes as necessary, but regularly runs at thermophilic temperatures. Thermophilic systems offer faster reaction rates and shorter processing times, but are generally more sensitive to changes in system temperatures, which can affect methane production. Biogas from the digester runs generators totaling 3 megawatts (MW) in capacity, and all electricity produced is sold to a local utility under a 20-year contract.
The Michigan state law requiring utility companies to obtain 10 percent of their power from in-state renewable sources by 2015 has helped to enable this $22 million project, which was also secured by a $12.8 million U.S. Department of Agriculture Rural Development Loan Guarantee. In the future, the operator plans to use excess heat from the facility's generators to heat and circulate hot water through the industrial park for use by other companies.
Media Contact: Kelly M. Farr, (248) 735-6684, ext. 124, firstname.lastname@example.org
Michigan Public Radio Environment Report, "Michigan Biodigester Turns Food Waste Into Energy," March 12, 2013
* Note: NOVI Energy also constructed a waste wood-fueled power plant in South Boston, Virginia. This $180 million project was completed in late 2013. http://www.novec.com/About_NOVEC/SBE.cfm
In 2006, the University of Wisconsin (UW)-Oshkosh was one of four UW campuses selected by Wisconsin's then-Governor Jim Doyle to take part in an energy independence pilot program. In short, UW-Oshkosh was challenged to produce or acquire enough renewable energy to offset all of its energy consumption. The campus adopted a comprehensive sustainability plan in 2008 and, armed with an aggressive Climate Action Plan, aims to achieve full carbon neutrality (i.e. offset all campus carbon emissions through energy efficiency and renewable power generation) by 2025. As part of its efforts, UW-Oshkosh completed construction in 2011 on an anaerobic digester and a combined-heat-and-power (CHP) conversion unit located directly across a river from the main campus. The facility was constructed by BioFerm Energy Systems through a public-private partnership, and is owned and managed by the UW-Oshkosh Foundation. The project has an expected lifetime of 20 years and a simple payback time of 10 years. Any profits to the UW-Oshkosh Foundation will fund student scholarships.
While most anaerobic digesters process "wet" materials, the UW-Oshkosh facility is the nation's first commercial-scale "dry" biodigester, meaning that the plant takes in source-separated organics in solid form instead of liquid slurries. At UW-Oshkosh's Reeve Memorial Union, students are encouraged to "Feed the Beast" by putting their food waste, napkins, and pizza boxes into separate receptacles for the anaerobic digester. The digester takes in 8,000 tons of food and yard waste annually; some of this feedstock comes from the campus, but the bulk is supermarket produce and yard waste collected by the City of Oshkosh. The source-separated organics are processed to yield biogas and biosolids that are similar to late-stage compost. The solid materials are sold within the state as fertilizer, and the biogas is used to maintain constant temperatures throughout the digester process and to produce electricity, which is sold back to the grid. As of summer 2012, the facility was operating at 50 percent capacity. When fully operational, it will be able to provide up to 10 percent of the campus's electricity and heat. UW-Oshkosh is also using the digester as a learning tool: the school invites visitors to come and see the system in action, and students collect data on the digester feedstock to determine its optimum composition. At UW-Oshkosh, anaerobic digestion is moving the campus closer to achieving its ambitious sustainability goals by generating clean, local, renewable energy.
UW-Oshkosh Today "Feed the Beast":
Through its Green Bin Program, the City of Toronto incorporates an environmentally-conscious option for source-separated organics processing directly into its Municipal Waste Management system. Residents of Toronto separate their organics and recyclables from the remainder of their waste, and the city collects the organics in special green bins. The residential organics are transported to the Dufferin Organics Processing Facility, which is located just outside of the city and has been operational since 2002. Inside, the facility maintains negative air pressure to prevent odor release, and the waste is sorted further to remove any unwanted materials. An anaerobic digester processes the sorted organics - approximately 770 tons per week - to generate biogas and solid digestate. The digester solids provide feedstock for a privately owned composting facility. The biogas is flared to reduce greenhouse gas emissions, preventing the average weekly release of 29,588 cubic meters of methane. The city is considering facility upgrades that would capture the biogas and use it as fuel.
The Green Bin Program has a participation rate of 98 percent among city residents, and it has been able to capture and divert more than 91 percent of the city’s organics from the landfill. Through citizen participation and public initiative, Toronto has successfully implemented and maintained a sustainable option for the disposal of organic waste, reducing the amount of waste it sends to landfills and its environmental footprint. Due to the Dufferin plant's success, Toronto is currently planning to build two more anaerobic digestion facilities to sustainably process even more of its waste.
Since 1998, University of California-Davis Professor of Biological and Agricultural Engineering Ruihong Zhang has been working on anaerobic phased solids (APS) and high-rate digestion (HRD) technologies to more effectively process high-solid organic wastes and use water more efficiently. Professor Zhang's work is an ideal complement to sustainability efforts currently underway in the Bay Area, such as the City of Davis' 2008 Climate Action and Adaptation Plan, which calls for a 15 percent reduction in greenhouse gas emissions by 2015 and full carbon neutrality by 2050. In addition, several local food waste producers, including Wal-Mart and Campbell's Soup, have committed to sustainability and need the proper infrastructure to help them follow through. In 2006, Professor Zhang and UC-Davis partnered with Onsite Power Systems and CleanWorld to build a pilot facility at Davis using the new digestion technologies. On Earth Day 2014, the university and CleanWorld officially unveiled the UC Davis Renewable Energy Anaerobic Digester (READ) at the campus’ former landfill. The system is designed to convert 50 tons of organic waste to 12,000 kWh of renewable electricity each day using state-of-the-art generators, diverting 20,000 tons of waste from local landfills each year.
The facility took unique advantage of its location at the now closed UC Davis landfill by blending landfill gases — primarily methane — with the biogas to create a total of 5.6 million kWh per year of clean electricity. It is expected to reduce greenhouse gas emissions by 13,500 tons per year.
The READ BioDigester encompasses several of the university’s goals: reducing campus waste in a way that makes both economic and environmental sense, generating renewable energy, and transferring technology developed at UC Davis to the commercial marketplace. Nearly half of the organic waste, or feedstock, needed to operate the biodigester will come from UC Davis dining halls, animal facilities and grounds. CleanWorld is working with area food processing and distribution centers to supply the remaining amount. Meanwhile, UC Davis will earn 100 percent of the project’s green energy and carbon credits and receive all of the electricity generated. Whatever is not turned into biogas can be used as fertilizer and soil amendments — 4 million gallons of it per year, which could provide natural fertilizers for an estimated 145 acres of farmlands each day.
The first commercially-available anaerobic digester using Professor Zhang's technology, developed by CleanWorld, began operating at American River Packaging (ARP) in Sacramento in April 2012. Each day, the digester takes in 7.5 tons of food waste and a half-ton of corrugated packing material from ARP to generate roughly 1,300 kilowatt-hours of renewable energy. This process meets 37 percent of ARP's electricity needs and prevents 2,900 tons of organics from ending up in landfills annually.
CleanWorld also built a digester and a renewable natural gas fueling station in south Sacramento. The Organic Waste Recycling Center is now processing 25 tons of food waste per day and construction is underway to expand the facility to 100 tons per day, converting the organics into 700,000 gallons of compressed natural gas to be used as fuel for both public and private vehicle fleets.
Since December 2010, an anaerobic digestion facility just outside Columbus, Ohio, has been processing sewage sludge and food remains to create renewable energy. Located less than a mile from the nearest residential area, the facility collects biogas from the controlled decomposition of organic wastes and uses it to generate daily up to one megawatt of renewable power and compressed natural gas (CNG) equivalent to the energy supplied by 3,600 gallons of gasoline. The Columbus facility also houses a CNG fueling facility, giving vehicle owners an option for renewable fuel. The digester is owned and operated in a public-private partnership between the Solid Waste Authority of Central Ohio (SWACO) (http://www.swaco.org/), Kurtz Bros. Inc. (http://www.kurtz-bros.com/), an experienced Ohio-based landscape and resource management business, and Quasar Energy Group (http://www.quasarenergygroup.com/), another Ohio-based company with a mission of generating affordable, renewable energy from organic matter. Quasar also operates other AD systems in Ohio, and partners with researchers at The Ohio State University's Agricultural Research and Development Center (OARDC) (http://www.oardc.ohio-state.edu/) to improve the performance of AD processes. The Columbus AD facility, just one product of these organizations' combined expertise, is helping Ohio meet its aggressive renewable energy goals while changing the way Ohio and its institutions think about waste management. In a sustainable hole-in-one, the Memorial Tournament, an annual PGA tour golf tournament, worked with SWACO and Kurtz Bros. in 2012 to dispose of the event's 5-10 tons of food remains in the Columbus digester. This effort, just one proactive step the Memorial Tournament is taking towards sustainability, brought the event closer to being "the greenest stop on the PGA Tour."
Columbus Dispatch (Memorial Tournament article):
PBS's coverage of Marie Audet's farm in Vermont. Economic information at the end implies energy bills go up with this technology.
Anaerobic Digester Construction Time Lapse
This video is soundless and incomplete, but still pretty interesting to watch.