by Colin Ellis, Vermont Business MagazineA dairy farm in the town of Franklin will soon be turning their animal waste into electricity for local buyers.
Riverview Farm has signed a contract with Bio-Methatech to build a biogas system on the farm in the spring of 2012. Using a process known as biomethanisation, the farm will be able to turn various forms of animal, farm and organic wastes into electricity, heat and animal bedding all while using a source of renewable energy. The electricity created will be sold to a public electricity network.
David Dunn, manager of renewables at Central Vermont Public Service Corporation, said that this is the first Vermont project for Bio-Methatech.
‘This is the first Bio-Methatech digester project in Vermont,’ Dunn said. ‘The system is fully designed, the contract is signed, all the financing is sorted out and construction will begin in the spring.’
Dunn added that this will be a turnkey project for Bio-Methatech. Turnkey refers to an arrangement under which a private contractor designs and constructs a project and sold to a buyer in ready-to-use condition.
‘Bio-Methatech has been hired as something comparable to a general manager of development and construction,’ Dunn said.
Biomethanisation is a natural biochemical process of recovery from the fermentation of organic wastes which creates the green energy biogas. The carbon-neutral gas is produced from the organic waste and is treated in a sealed tank known as an anaerobic digester. The process reduces methane emissions into the atmosphere.
Biogas itself is made of 60 percent to 70 percent methane, which is captured and burned in the co-generator to create heat and energy. Heat produced by the co-generator will be recovered and used to maintain the temperature of the digester as well as heat the buildings. This generator also produces electricity from the biogas, which in turn is fed back into the electric grid.
Carbon neutrality refers to removing as much carbon dioxide from the atmosphere that is being put in.
Biomethanisation, according to proponents, provides a renewable energy source, a positive energy balance, a reduction of greenhouse gases, clean and quality animal bedding, economic benefits and a respectful cycle of organic waste.
Riverview is just the latest dairy farm in Vermont to generate electricity in this manner, or what CVPS calls Cow Power. The owners of the farm have a herd of 450 dairy cows and intend to sell the electricity produced into the electric grid, as well as use the pressed residues for animal bedding. The residues are also odorless.
According to Rob Achilles, an engineer at Vermont Agency of Agriculture, Food, and Markets, there are at least 10 other farms run through CVPS with more likely on the way.
‘A lot of farms are already doing it, and a lot of farmers are excited about it,’ he said.
Achilles said that the Agency played a mostly advisory role to Riverview, such as helping them choose between types of manure, but did not play a direct role in designing the farm.
Alison Kosakowski, the marketing and promotions administrator at the Agency, said that biogas farms are a growing trend.
‘It’s a great, innovative technology. We’re seeing people use it more often,’ she said. ‘The interest is strong, but making one takes a lot of investment.’
To decrease the high costs of creating a biogas farm, Riverview and other farms go through a grant process. There are a number of grants available to help cover the costs of producing a biogas farm, Achilles said.
The costs of a biogas farm vary depending on how many cows the farm has, according to Dunn, with most typically costing around $2 million to build.
Both Achilles and Kosakowski said that the Agency is supportive of the new technology.
Riverview is just one of four Cow Power projects currently in construction. Maplehurst Farm in Greensboro, Four Hills Farm in Bristol and Vermont Technical College in Randolph are all set to receive new generators, according to the CVPS website.
According to Dunn, most Cow Power farms in Vermont employ the Wisconsin-based DVO flow-plug system. A plug-flow system operates by feeding manure into one side of the long and narrow concrete tank. The manure is pushed forward as more is added behind it, and usually does not utilize any mechanical mixing. A flow-plug usually takes more solid wastes, in the range of 11 to 14 percent solids. Retention time, how long the waste remains in the digester, for the flow-plug system is usually 15 to 30 days.
The Bio-Methatech model is a complete mix digester. They can be used to treat more diluted wastes, usually between 2 and 12 percent. The mixing action of this digester keeps the solids suspended in solution. Retention time for the complete mix digester is usually 10 to 20 days.
Bio-Methatech is a Canadian based company founded in 2006 that design and build the digesters used to create biogas. The company uses the technology of LIPP GmbH, a German design. LIPP has constructed and commissioned over 700 installations worldwide over a period of 35 years.
The patented LIPP Double-Fold System provides long lasting and high quality systems with quick and easy installation. The LIPP folded system has a unique spiral shape, giving its tank a high level of stability and making the entire system resistant to horizontal pressure.
The digesters are designed to operate at temperatures that ensure the survival of anaerobic methanogenic bacteria, usually found in the stomachs of cows, anywhere from 98 to 107 degrees. The digester’s mixing system periodically brings floating oils and fats to the bottom to be methanized, meaning converted into methane.
There is an overflow system in the middle of the digester, where organic matter is fully digested. There is a drainage system located in the bottom of the digester. A rotating current inside the digester ensures that sediments do not accumulate in this area. The heating system offers a high rate of heat transfer and low power consumption.
The LIPP system stores the biogas safely. The digester integrates a low pressure reservoir tank and a solid roof structure, which permit the storage of produced biogas for a later use.
Decomposing manure, used in the process, releases nitrous oxide and methane. Respectively, the two gases warm the atmosphere 310 times and 21 times more than carbon dioxide. Biogas plants eliminate the impact of these gases while generating renewable energy and inexpensive electricity.
Biogas can be compressed into liquid natural gas and used not only to heat homes but also power compressed natural gas vehicles. The methane content in biogas can also be concentrated and upgraded to create bioethanol, another alternative fuel for cars, trucks, and busses.
Biogas produced on several other Vermont dairy farms has been included in the CVPS Cow Power program as a voluntary tax. In this program, customers can elect to pay a premium on their electric bill and that premium is passed directly to the farms on the program. Customers can opt in to a manure-to-methane program.
CVPS customers also have the option to register anywhere from one-quarter, half or all their electricity to come from cow power. They pay a premium of 4 cents a kilowatt hour. This premium goes to participating farm-producers, to purchase renewable energy credits when farm energy isn’t available or to the CVPS Renewable Development Fund. This fund provides grants and project support to farm projects.
Colin Ellis is a freelance writer from Colchester.