Methane Digester Produces Enough Electricity to Light 800 Homes
(Farm News - November 2009)
This Dairy Farm is a Real Powerhouse
Pagel's Ponderosa Dairy LLC, is more than a dairy farm. It's an educational facility, a multi-generational family business and a renewable energy source.
Carl and Garnet Pagel started the Kewaunee County farm in 1946 with eight cows, but oh, how it's grown. When son John took over the operation in 1980, he was milking 65 cows. He expanded the operation several times in subsequent years culminating with the addition of a methane digester in December 2008. The year 2009 started with a planned expansion from 1,500 to 4,600 cows, which included the addition of two barns — each three football fields long — and a spacious office facility.
Today more than 125 people are employed by Pagel's Ponderosa, including four of John's children and two of his children's spouses. Grandchildren frequently make themselves at home playing in the farm office — living proof, Pagel said, that a large farm can still be a family farm.
Cow Power
Saying that 4,600 cows, along with 2,500 heifers and 400 calves, produce a lot of manure is an understatement, so Pagel looked for a way to make it more of a product, not simply a byproduct. He concluded that an anaerobic digester would benefit his operation.
In an anaerobic digester, naturally occurring bacteria break down manure into a variety of gases, including methane. A cover on the digester traps this biogas, which is passed through an electrical generator. The electricity produced by the 800-kilowatt generator on the Pagel farm is sold to Wisconsin Public Service.
Adding an anaerobic digester, however, is no small expense. Pagel said the total investment was $3.2 million, and payback takes an estimated 7 to 10 years depending on the rate paid to the farmer for the electricity. But, he added, there are other benefits including an endless supply of bedding, made from the solids that are separated out of the manure, which keeps cows comfortable on the Pagel farm and three other area farms.
"And comfy cows produce more milk," said Pagel, whose comfy cows are milked in a revolving 72-stall parlor three times a day.
The solids from the separated manure also make great fertilizer, which Pagel supplies to area gardeners. The heat of the digester kills weed seeds and bacteria in the manure and the end product is almost odor free. In fact, Pagel said, the most important benefit of a digester may be odor reduction.
Because anaerobic microorganisms break down many odor-causing compounds in manure as it moves through the digester, odor problems are basically eliminated. In fact, research has shown anaerobic digestion reduces odor by 97% over fresh manure.
Pagel said after it goes through a separator, less than 3% solids remain in the manure. That liquid is then used to irrigate the fields, but it doesn't smell like traditional field applications of manure.
"It's hard to put a value on that," Pagel said. "When we decided to add this many cows in one location, it was our responsibility to make sure we'd still be good neighbors. We have had no complaints or requests for hearings from neighbors. They love that we are making renewable energy."
Committing to a Digester
The cost of a digester depends on specific farm conditions and payback can vary. Systems will use about 30% of the biogas to heat the digestion system and typically a minimum herd of 500 dairy cows or 2,000 swine is needed to make such a system feasible.
Money isn't the only consideration, when considering a digester, however. Daily maintenance is required to keep a digester working smoothly. This includes system inspection, mixing and pumping manure into the digester, and checking and recording gauges to measure biogas and electricity output. Making sure the Pagel farm's GHD, Inc. digester is running properly is the job of John's son, Bryan. He monitors the panels to make sure the manure never goes below 85 degrees and, as with any other heavy machinery, he has to change the oil and sparkplugs and set the valves regularly. What's convenient for Bryan, however, is that he doesn't have to be on-site watching the equipment 24 hours a day. The engine will send him a text message, if there is a problem, and he can often execute the fix from his home.
The Pagel's generation system is also in constant communication with the Green Bay headquarters of WPS, which purchases the power produced by the digester. WPS Agricultural Consultant Alan Gregory, who worked with the Pagels throughout the installation of the digester, said the need to include that "communication pole" that allows the generator to communicate with the utility was just one of many things he learned on the project.
"I have really enjoyed working with John and Bryan on this project," Gregory said. "It was my first digester and we all learned a lot along the way."
A Mission to Educate
Learning is not unusual on the Pagel farm. It seems everyone who sets foot on Pagel's Ponderosa learns something, and that's intentional.
Part of the most recent expansion of Pagel's Ponderosa includes office facilities complete with a 60-seat "theater" and a large viewing area overlooking the milking parlor. These amenities are used to host tour groups and school field trips. After touring the facilities, groups gather at the tables in the theater area to watch an educational film about the dairy industry in Wisconsin. Soon a film specifically about the Pagel's operation will be screened as well.
"We had 300 elementary school kids here last week," Pagel said. "I believe so strongly in education it is definitely worth the investment."