April 21, 2011 | General

Anaerobic Digest

BioCycle April 2011, Vol. 52, No. 4, p. 14

Madison, Wisconsin
The Wisconsin Office of Energy Independence reports methane gas produced by anaerobic manure digesters generated 657.1 million Kilowatt hours for that state in 2009. That figure is up almost 600 percent from a 1995 figure of 110.1 million kilowatt hours. Considering the average household uses about 10,000 kilowatt hours a year, that’s enough to power more than 67,000 homes.
This makes Wisconsin the nation’s largest producer of electricity from livestock manure in the nation. “Anytime we can deploy technology to use our feedstocks from dairy farms, that means we are adding value to our economy in the state,” Judy Ziewacz, executive director of the Wisconsin Office of Energy Independence, told the Oshkosh-based newspaper The Northwestern. “What is considered a waste … is an energy source, and we add values to farmers and rural communities.”
In its 51st year hosting the WPS Farm Show, Wisconsin Public Service showcased its own efforts to encourage development of farm power. This includes purchasing power from 11 of 26 manure digesters generating electricity from methane across the state.
United Kingdom
Anaerobic digester (AD) projects under way in the United Kingdom include a 2 MW plant being built by Shanks, a waste management firm near Aylesbury, with the capacity to process 48,0000 metric tons/year of feedstock – mostly coming from food industry organics in the region – and a facility being built by green energy company Local Generation in Cambridgeshire with the capacity to process 30,000 metric tons/year of organics. Returning from a recent trade mission to the UK, Boston-based PMC BioTec announced plans to expand its biogas business operations in Britain based on that country’s stated commitment to supply 20 percent of its total energy by means of renewable energy by 2020. This includes an allocation of more than 200 billion pounds (more than $325 billion) for related projects.
And in a minor shakeup for the solar industry, the UK government announced in March its intention to redraft a year-old tariff for green electricity in a manner that would encourage AD projects, particularly those tied to the recycling of organic wastes, while trimming back payments for solar production. According to published reports, the country’s Department of Energy and Climate Change had expressed concern that the original feed-in tariff for electricity from renewables held the risk of creating more solar power than the department could afford and did not provide enough incentives for AD.
Warrensburg, Missouri
The first large-scale anaerobic digester to be utilized by the U.S. poultry industry is scheduled to go online in early 2012. Built by BioStar Systems, LLC, of Kansas City, Missouri, on a 12-acre parcel of land across the street from and owned by the Johnson County Egg Farm, the facility will process waste from 2.4 million chickens.
The $30 million project was largely funded through $27 million in state of Missouri Recovery Zone Facility Bonds, with an additional $450,000 grant from the Energize Missouri Renewable Energy Biogas program. Waste will be pumped from the chicken houses to the digester. Biogas will be scrubbed and injected into a pipeline owned by Southern Star Gas Pipeline Co. and transported to regional utilities for distribution to customers.
Currently, wet waste from the poultry operation is land applied and the dry waste is sold to local farmers as fertilizer. Once the digester is online, digested solids will be further dried and granulated to make organic fertilizer. A spokesman for the egg farm said the 4 million gallon capacity digester will reduce both odors and labor costs.
Kansas City, Missouri
Ever wonder how to make an anaerobic digester at home? A new DIY video produced by the Urban Farm Guys will show you how. The “Guys” are actually 20 families who voluntarily uprooted themselves from comfortable suburban homes and collectively transplanted themselves into one of Kansas City’s most blighted neighborhoods. Buying homes within a five block radius, these socio-environmental crusaders have gathered alternative technologies in energy and food production from around the world to be tested in their new homes and shown on their website.
“Today we’re going to bring you into the world of biogas digestion,” offers a thirty-something host as he stands in a residential driveway amidst two of four home-scale digester projects featured in the 14-minute film. The narrator explains to the viewer how the Urban Farm Guys pick up rotting food waste from local restaurants to feed to their digesters. About 800 pounds recently collected will produce methane for up to eight weeks. The largest system the group has designed so far consists of three IBC toters hooked together, with capacity to accommodate around 100 pounds of food waste daily. The toters are spray painted black to soak up heat, which both warms their contents and heats the greenhouse in which the digester is housed. Methane is collected off the tops of all three tanks. The Urban Farm Guys also explain the science, such as how to inoculate the digester, why it’s critical to maintain proper pH and how to do so. See the DIY video and learn more about the Urban Farm Guys at
Palo Alto, California
Voters will get to decide whether a composting and renewable energy project is an appropriate use of a public space. Supporters of the Palo Alto Green Energy and Compost Initiative gathered signatures of 5,128 registered voters to put the matter on the November ballot, surpassing the required 4,356 votes by about 15 percent. According to published reports, more than 60 volunteers collectively dedicated several hundred hours to gather the signatures.
At issue is development of 10 acres of a 126-acre landfill adjacent to Byxbee Park for a proposed anaerobic digester (AD) and composting facility to recycle the municipality’s 60,000 tons of organic waste generated annually into energy and compost when the landfill closes next year. If the initiative does not pass, the entire 126 acres would become part of the public park.
Opponents of the project have stated that building an AD facility would require millions in taxpayer dollars and that there are less expensive ways to deal with the city’s organic waste stream. Supporters of the project stated in a public meeting that the project could actually save the city between $30 million and $38 million over the first 20 years it is online.
Portland, Oregon
“Oregon’s dairies, wastewater treatment plants (WWTP), MSW collectors and food processors have the feedstock and infrastructure to generate over 100 megawatts (MW) of biogas energy, but currently only have 8 MW installed,” according to a newly released study, “Growing Oregon’s Biogas Industry,” researched and written by Peter Weisberg of The Climate Trust and Thad Roth of the Energy Trust of Oregon, both based in Portland. “Dairy farms have the greatest potential to generate biogas energy, and WWTPs currently generate the most.” Tapping the state’s biogas potential could create at least 300 new, permanent full-time jobs and reduce annual greenhouse gas emissions by 800,000 metric tons of CO2 equivalent, note the authors.
The report goes into detail on the state’s industries with the greatest potential to generate biogas, discusses unique economic and environmental benefits of anaerobic digestion plants and recommends policies to accelerate their construction. Financial barriers are cited as a prime deterrent to construction of new facilities. It recommends two Oregon policies to help overcome this barrier to entry: 1) Production incentives, including Renewable Avoided Cost Rates (pricing biogas to reflect the value of renewable resources), feed-in tariffs and enhancements to the state’s Renewable Portfolio Standard (e.g., specify a percentage of electricity that must be purchased from biogas plants and credit thermal biogas energy); and 2) Bridge loan program to provide financing for project construction. The report can be downloaded at:
Newport, Rhode Island
Rhode Island’s Aquidneck Island shares a challenge common among populous East Coast isles – no room for the refuse. That’s one reason a proposal by a lifelong Newport resident to build an anaerobic digester for recycling of organic waste rather than sending it to the landfill has caught the attention of public officials. Marty Grimes, former chair of the Newport Energy & Environment Commission, wants his company Rhode Power to build the digester and is working with a U.S. senator’s office to secure $100,000 for a feasibility study, the Newport Patch reports. According to the newspaper, Grimes is trying to secure Navy property for a pilot project and would provide the base with the produced biogas.
Grimes presentation to the Rhode Island Resource Recovery Corporation (RIRRC) – which has kept a weary eye on Aquidneck Island’s almost-at-capacity landfill – met with favor because it buys some time. The RIRRC went so far as to offer him a 6-acre site at the landfill. “Aquidneck Island is the ideal location in the state of Rhode Island for this technology,” Grimes told the Newport Patch. “If we run out of room at the landfill, we’re going to have to ship our garbage out of state.”

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