Cows rest on the bedding that is an odorless byproduct of their manure that has been renewed through an anaerobic digester on Kenn Buelow’s farm north of Chilton, WI.
Posted on 06/05/2005 9:43:00 AM PDT by Diana in Wisconsin
Interest grows in digesters that turn manure into energy, fertilizer and bedding for cows
Chilton - The manure management side of farming is far less smelly and far more profitable when the animal waste is converted into a power source.
Such a biomass process is up and running at farms across Wisconsin and other states. Although the basic technology isn't new, it's generating attention for a local company, GHD Inc.
Company owner Steve Dvorak has run a farm implement dealership for 27 years. The farm boy turned engineer kept hearing farmers complain about manure management, and ended up developing his own line of anaerobic digesters, or waste-to-energy processors, in a complex system born of the simplicity of nature's call.
His business, with 11 employees, sells such systems around the state, across the country and now overseas.
In an anaerobic digester, cow manure is funneled in 24-inch underground pipes to long underground caverns, about the length of a football field.
A generator is used to heat the manure to 100 degrees; the reaction from the heated manure, in turn, helps run both the generator and power other parts of the farm. Unneeded power is sold to the broader electric grid.
What's left: Lagoons of wet manure, minus the toxins - and suspended solids, an odorless remnant of cow dung that is used for cow bedding.
Dairy farmer Kenn Buelow runs a 3,700-cow, 30-employee dairy, Holsum Dairies, in Hilbert just outside Chilton. His GHD system, while costly, allows his large farm to operate in an area where other farmers routinely receive complaints about flies and foul odors.
Savings every month
Cost savings come every month, thanks to the power he's selling to Green Bay-based utility Wisconsin Public Service Corp, and from the heat his system provides his barns, milking parlor and office. Other savings: He no longer has to buy commercial fertilizer for his farm fields, and he can spread the liquid manure all summer long rather than waiting until fall.
"Plus there's the $10,000 a month we don't have to spend on bedding," he said.
His cows are so prolific, that the bedding byproduct is now being sold to 11 farmers, one as far away as Antigo, Buelow said.
Anaerobic digesters have been around for decades, but they're getting more attention as utilities look to whet customer's appetite for energy from renewable resources.
From a purely economic standpoint, the technology is not competitive with power purchased from a utility. Dvorak says his system is cost-effective for herds of at least 400 to 500 cows, at least with current technology.
Bill Johnson of Alliant Energy Corp. of Madison compares the status of digesters today to where wind turbines were at more than a decade ago. Since then, wind power has gotten more competitive, through better technology, longer blades, taller towers and higher costs of other forms of generating electricity.
Long term, the potential for wider application is great, says Johnson, manager of agricultural compliance for Alliant's utility, Wisconsin Power & Light Co.
After all, even the best sites for wind turbines can't generate electricity all the time because the wind isn't always blowing, he said. Cows are always eating, digesting and creating waste.
"Anyone who's ever worked behind a cow will know that this is a renewable resource that's there all the time," he said.
Many advantages
But Johnson said there are many other advantages to having a digester - environmental and economic.
It helps combat fly problems, it's sustainable, and it could soon play a role in preserving the family farm.
In the next year or two, he predicted, smaller scale systems will become more economical, permitting farmers whose herds are fewer than 500 cows to take another look at digester projects they've written off as too costly in the past, Johnson predicted.
"That will be important because of urban encroachment," he said. "People want the rural life, but they don't want to smell it. There's going to be more and more pressure on dairy agriculture."
Anywhere farmers are
Dvorak sees a market for the systems wherever farmers are located. That took him to northern Illinois last month and is taking him to Georgia this week to oversee installation of a system.
Another system is being installed in Siberia, and the company sees customer interest from Canada and Mexico as well, Dvorak said.
"Kenn was one of the first ones to do it," Dvorak said of Buelow. "But it's starting to come."
Buelow's digester was one of the first built by GHD.
Today, seven farms with 15,000 cows are making energy from manure using GHD technology, the company said. That includes several in Wisconsin and others in Vermont, Washington and Indiana.
In addition, the U.S. Department of Agriculture has awarded rural business development renewable energy grants in the last two years based on GHD technology to 31 farmers, including 21 in Wisconsin.
The growth of manure power is being watched in Madison, where a renewable energy task force appointed by Gov. Jim Doyle recommended that the Legislature encourage development of more anaerobic digesters across Wisconsin.
The task force said it sees waste-to-energy systems, also known as biomass, as playing a role in helping Wisconsin meet the goal of having 10% of its electricity generated from renewable sources by 2015.
"As electricity prices continue to rise and the costs of renewable energy systems fall, a growing number of Wisconsin's large farms are implementing anaerobic digestion - manure-to-energy renewable energy systems - to reduce their utility bills and improve the environmental performance on the farm," said Don Wichert, director for Focus on Energy's renewable energy program.
Focus on Energy, which gave Holsum a $55,000 grant to help with the GHD system, estimates that his system generates 1.6 million kilowatt hours of electricity and more than 109,000 therms of energy a year, enough to keep 2,500 tons of carbon dioxide from being released in to the atmosphere.
Cows rest on the bedding that is an odorless byproduct of their manure that has been renewed through an anaerobic digester on Kenn Buelow’s farm north of Chilton, WI.
IISc(Indian Institute of Science) Biomass Gasification Process
DESI Power's analysis at the start of its programme was that biomass gasification was the most promising technology for providing affordable and competitive electricity supply and energy services to rural areas where agricultural and plantations wastes were available. A large parts of the wastes are, of course, being used in various forms for cooking, drying, fodder and building materials, with the largest part being burnt at very low efficiencies. In addition to such a waste of a valuable raw material, there are other serious adverse effects resulting from the traditional ways of burning biomass: exposure of women to smoke and carbon monoxide which causes respiratory and asthmatic disease, indoor and outdoor air pollution and smog, and the traditional servitude of girls and women for the collection and processing of cooking fuel.
DESI Power's aim was to look at modern new technologies which utilise the available agro and plantation residues at much higher efficiencies than in the traditional usage to generate electricity in a reliable manner. The goal was to utilise the selected and proven energy technology in a socially fair commercialisation system which enabled the villagers to establish and own local value addition chains for the production of goods and services which also generated local jobs. Energy services for cooking, lighting, water supply and social services was planned to be provided as an integral part of the village project.
Principles of Gasification
Biomass is a natural substance, which accumulates solar energy as chemical energy by the process of photosynthesis in the presence of sunlight. Biomass chiefly contains cellulose, hemi-cellulose and lignin, having an average composition of C6H10O5, with slight variations. For the complete combustion of biomass the theoretically amount of air required (defined as the stoichiometric quantity) is 6 to 6.5 kg of air per kg of biomass and the end products are CO2 and H2O. In gasification, biomass is subjected to partial pyrolysis under sub-stoichiometric conditions with the air quantity being limited to 1.5 - 1.8 kg of air per kg of biomass. The resultant mixture of gases generated during the gasification process is called producer gas, contains CO and H2 and is combustible. The raw producer gas also contains tar and particulate matter which have to be removed as they are harmful to the engine.
A typical gasifier plant based on IISc technology consists of a reactor, which receives air and solid fuel and converts them into gas, followed by a cooling and washing train where the impurities are removed. The clean combustible gas at a nearly ambient temperature is available for running diesel-generator sets in dual fuel mode or gas engine generator sets suitable for running on producer gas alone. In thermal applications, the cooling and cleaning of the raw gas is limited to the requirements of the thermal process.
In the down draft reactor, biomass feedstock undergoes drying and de-volatilisation in the upper zones and produces char. The volatile matters undergo oxidation in the combustion zone, with air being partially drawn from the open top and partially supplied by air nozzles located after the de-volatilisation zone. The gas then flow through a hot charcoal bed in which the tar produced earlier is burnt. This is the special feature of the IISc gasification process which enables the tar in the raw producer gas to be maintained at relatively low levels. Special washing and cleaning systems developed as an integral part of the gasification system further reduce the levels of tar and particles in the cold producer gas to very low levels. These are the features which are responsible for enabling the engines to run for long operating hours with maintenance requirements which are similar to those specified for pure diesel or pure gas firing.
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CO: 20 + 2%; CH4 : 3 + 1%; H2 : 20 + 2%; CO2: 12 + 1% ; Rest: N2 The lower calorific value is about 4.5- 5.0 MJ/kg (1000 - 1200 kcal/ m3). |
Applications
Obtained by the process of gasification, can be employed in thermal application or for mechanical / electrical power generation. Like any other gaseous fuel, producer gas affords much better control over power levels when compared to solid fuel. This also paves the way for more efficient and cleaner operation.
For thermal applications, gasifiers are a good option as a gasifier can be retrofitted with existing devices such as ovens, furnaces, boilers, etc. Thermal energy of the order of 4.5 to 5.0 MJ is released by burning 1 m3 of producer gas in the burner. Flame temperatures as high as 1200° C can be obtained by optimal air preheating and pre-mixing of air with gas. Producer gas can thus replace fossil fuels in a wide range of devices. A few of the devices which could be retrofitted with gasifiers are furnaces for melting non-ferrous metals and for heat treatment, tea dryers, ceramic kilns, boilers for process steam and thermal fluid heaters.
A diesel engine can be operated on dual fuel mode using producer gas. Diesel substitution of over 80% at high loads and 70 - 80% under normal load variations can be achieved. The mechanical energy thus derived can be used either for driving water pumps for irrigation or for coupling with an alternator for electrical power generation. Alternatively, a gas engine can be operated with producer gas on 100% gas mode with suitably modified air / fuel mixing and control system.
I'm involved with a project at NC State doing this very thing, except on hog waste. We've come up with a couple of really interesting wrinkles that should (in theory) reduce the residuals, increase the production of methane and remove the nitrogen before water effluent is discharged. Of course, bovine waste is somewhat simpler because you can dry it and burn it for fuel directly. Pigs are pretty nasty animals.
That looks suspiciously similar to the process the nazis used near the end of WWII as they were running out of fuel, using wood chips to make fuel. Note the heat content (~1,200 kcal/cubic meter). That's a lot less than natural gas at ~1,100 btu/cu.ft (I'm too tired to do the coversion right now, sorry)
Could you please give me a link to the Nazi gasifying process? I'll try on my own meanwhile.
This is all bull$#!+ :)
(/lame attempt at humor)
Why remove the nitrogen? Leave it in, sell the water to farmers to spread on crops, cheaper than buying fertilizer.
Chilton and manure in the same sentence???
Billy Rubin must be laughing his head off.
"I would have figured that there weren't any milk cows in Alaska, but there is one dot..."
That must be the "magic cow" that makes ice cream! :)
Cool map! I can look out my window from where I'm sitting and count over 50 cows across the road. They're everywhere! They're everywhere! ;)
You clearly have not been exposed to the joys of the Clean Water Act and ammendments. The biggest problem with your suggestion is the daily volume of water involved. It would be impractical to transport several hundred thousand gallons per day. Also, there are strict regulations in place for land irrigation in order to avoid runoff. Second, its illegal to irrigate crops for human or animal consumption with treated wastewater without jumping through mucho hoops first (if even then).
But aren't the byproducts 99.9999% pathogen free.?
They seem to be doing it in WI.Your'e problem may be in the amount of water coming from pig effluent as opposed to cow. Is there a way to evaporate the majority of the water to leave a usable product?
LOL and they all belong to the State
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