January 30, 2004 | General

On-Farm Digesters In The Midwest

Richard Mattocks
BioCycle January 2004, Vol. 45, No. 1, p. 56
When neighboring farmers tell Jerry Stencil, a dairyman near Green Bay, Wisconsin, that they are building a new dairy, his response is: “Put a digester as number one on the list of things to install. The value of the treated fiber as bedding will nearly pay for the system (even if you don’t count the energy value of the biogas.)” Stencil then continues: “Don’t forget neighbor relations are also improved – plus there is the added value of bonuses from improved milk quality.”
If there is a single message to convey from the Midwest, it is: Digesters are functioning well, and owners now recognize there is more value to digesters than power production alone.
The gold standard for manure digester value has traditionally been how much electricity can be produced. With more operating systems, operators recognize other values. Odor reduction is a major consideration for installing systems now, and neighbor complaints are drastically reduced. Recovered digested solids are being valued as a bedding material; most Midwest dairy manure digestion systems are recovering solids for bedding. Sale of surplus solids (as compost) is common, generating yet another revenue stream. Also, owners recognize crops are not “burned” when receiving nutrient-rich treated manure even when spread in midgrowth season. Finally, at least one producer places significant monetary value on the apparent success his digester is having on killing weed seeds, as he reduces his use of herbicides. Owners will also confirm that system demands on personnel is seldom over one hour per day.
This article provides a status report on the known digesters, which are operating, in start-up or in construction. Manure digestion systems are now available “off-the-shelf”. The following discusses the state of the industry in the Midwest as of November 2003.
Several manure digesters are in operation in the Midwest. More are in start-up or under construction. Over a dozen were funded under the recent USDA Renewable Energy Grant Program. Following a long period of gaining the confidence of agricultural producers, lending institutions, regulators and utilities, finally manure digester numbers are ramping up.
Located near the Illinois border, about midway between Chicago and Indianapolis, Fair Oaks dairy is a state-of-the-art facility. The website, “,” provides a virtual tour of the facility, including the digester designed by Cyclus Enviro Systems. The system is designed for 3,500 cows bedded with sand. Installation is for odor control and nutrient management purposes. Under construction during 2003, the four vertical plug flow digesters have experienced weather related delays. Manure is removed from the alleys with a vacuum wagon. The vessels were loaded in mid-November, 2003. Biogas from the vertical plug flow digester will be used for power generation, and projected cost is $750/cow.
Located just opposite I-37 from the Fair Oaks Dairy, the 10,000 head Herrema Dairy (formerly Bos Dairy) is bedded predominantly with sand. One barn, with about 3500 Holsteins, is bedded with treated separated solids. Manure from this is being fed into a mixed horse shoe plug flow digester designed by GHD, Inc.. The digester has performed well, though the dairy is currently installing a boiler to supply biogas fueled heat to the digester following challenges with the cogeneration internal combustion engines. “Manure without a digester is nothing but a liability, a total cost. With a digester, you heat floors, produce bedding and power to save on electric bills,” says Glenn Musch, digester operator at Herrema Dairy. Projected cost is about $450/cow.
Located just north of Galesburg, Illinois, Apex Pork was under scrutiny from state officials and the local community. Since the winter, 1998 installation of the RCM Digesters’ intermittent mix heated covered lagoon digester, the farm has received no complaints from the community. Biogas from the 8,000 finishing hogs fuels a boiler supplying heat to the digester. A flare burns surplus biogas. Projected cost is about $20/hog.
Formerly known as Inwood Dairy, New Horizons installed its digester in 2002, and has been operating for over a year. Scraped manure from 2,000 Holsteins is pumped into two side-by side plug flow digesters designed by RCM Digesters. Hot water recovered from the cogeneration system is stored in a large insulated tank and used for digester and in floor heating. Projected cost is about $500/cow.
Near Westgate in Northeastern Iowa, Top Deck  has a truly innovative energy contract with Alliant Energy. Biogas is sold to Alliant Energy for use in that organization’s 130 kW cogeneration system and turbine. Concerned about possible impact on the neighborhood when they doubled the size of their herd, dairy owners sought the assistance of the Iowa Department of Natural Resources to design a digestion system for what was to be 700 cows. The “U” shaped fixed top plug flow digester has been in operation since 2002. Cost per cow is about $600 for the digester, engine room and cogeneration equipment. They’re amazed they don’t know I’m spreading. And we’re only a mile upwind of the town,” says owner Roger Decker. A 100 kW Waukesha and a 30 kW Capstone turbine are used for power generation.
At the Northeast Iowa Dairy Foundation in Calmar , the Iowa Department of Natural Resources is cooperating with this learning institution located in the northeast corner of the state. Under development for a couple of years, the system is slated for full operation as a teaching tool at the college. This plug flow hard top digester was designed for 100-150 cows. Cost is more than $1,500 per cow. Currently a boiler is in place for use.
The Haubenschild Dairy in Princeton has received the Governor’s Environmental Award and has continually processed all manure from its dairy production herd (currently 900 head) since start-up in 1999. The Caterpillar 3406 has operated over 99 percent of the available hours. Estimated cost is $400/cow. (See page 44 of December, 2003 BioCycle for more details of operations at the Haubenschild Farm.)
Permitting of the construction of the new 3,000 head Jersey herd dairy at Northern Plains received the close scrutiny of the community and state regulatory bodies. The RCM Digester system was installed simultaneously with construction of the barn complex. Solids are recovered for bedding. Digester is the two side-by-side flexible top plug glow type, and 100 percent of the manure is processed. Reasons for construction were bedding, odors and neighbor relations. Projected cost is $500/cow.
The state has an aggressive biogas program, with multiple agency involvement as well as wide industry interest and active involvement. Of particular note is the Focus on Energy program and various state agencies. Nearly a dozen Wisconsin digesters were approved under recent USDA funding.
At the Baldwin Dairy and Emerald Dairy, three covered lagoons (1998 and 1999 installation) have completely achieved the goals set forth by the owners for which they were installed: for reduction of odors from the manure storage pits and to reduce the quantity of precipitation entering the storage vessels. Tiry Engineering provided the dairy with the design. The owner, John Vriez, expresses a willingness to communicate with any dairyman regarding his systems. Email address:
The two farms have 1,100 and 1,600 Holsteins; biogas is flared; and project cost is $65/cow (cover and gas collection only).Mapledale Farms is a duck farm; this complete mix system has been in operation since 1988, designed by Applied Technologies. Not until 2002 was the biogas used to fuel a cogeneration system. Manure from 500,000 ducks is digested. Odor control was the reason for construction.
At Double S Dairy,  manure from about 900 lactating animals is removed with recycled flush waters. No dry cows or young stock contribute manure to the digestion system. The system has been in operation since 2002. Cogeneration equipment (about 165 kW) is operating about 90 percent of the available hours. System is a mixed “U” plug flow type.
At the Gordondale Farm (Deerridge Farm), manure and all parlor water from this 700 head facility pass through a flume to a collection tank where it is pumped to the GHD design digester. The system has been in operation since 2002. Gas is sold to Alliant to fuel an engine generator set. The owner is pleased with what he senses are enhanced crop yields. Project cost for the digester is $375/cow.
Operational since 2001, Stencil Farms RCM Digester system has permitted significant improvements in odor and herd health. The farm switched from bedding with undigested recovered fiber to fully treated recovered fiber. Projected cost for the flexible top plug flow system is $500/cow.
The Tinedale Dairy in Wrightstown, Wisconsin, has been a consistent champion of improving the methods used to manage manure. In this developmental mode, technologies on the farm have changed, impacting system costs. The STS designed system has been in operation since 2002. All manure from 2,400 cows is being processed through the mesophilic digester. System is the fixed top “U” plug flow. See report, “Solid Separation of Dairy Manure,” by John Katers in December, 2003.
At the Wholesome Dairy which has been in operation since 2002, this side-by side fixed top “U” style GHD digester has been processing all manure from about 3,300 cows (lactating and dry) and some food processing waste streams. This is a new dairy. Apparently, the digester was a condition for permission to build. Projected cost is $500/cow.
Richard Mattocks is founder of Environomics, Inc., based in Riverdale, New York. His website is: This article is based on his presentation at the BioCycle Third Annual Conference on “Renewable Energy from Organics Recycling” in Minneapolis November 17-19, 2003.

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