By David Schmidt
British Columbia dairy operation installs anaerobic digester, believing one day a cow’s manure could be worth as much as its milk
By David Schmidt
Several dozen people toured the new anaerobic digester at Seabreeze Farms in Delta, B.C., Jan. 31. The system mixes manure from the farm with green waste from Metro Vancouver to produce biomethane for Fortis B.C. Photo by by David Schmidt
Can you change manure from a cost to manage to a prime revenue generator on the farm?
Jerry Keulen of Seabreeze Farms in Delta, B.C., not only believes you can but believes a day may come when a cow’s manure could be worth as much as its milk. That’s why Seabreeze has become the first commercial B.C. dairy farm to install an anaerobic digester.
After seeing digester’s on several European dairy farms, Keulen was convinced anaerobic digestion could address several issues for his farm:
- the additional income from green waste tipping fees and from the gas being produced would help support the three families (Keulen and his two sons) who rely on the farm for their livelihood,
- it would process the manure so liquid could be reused to flush the barns and fiber reused as bedding for his 250-cow milking herd, thereby also reducing the amount of waste which needed to be spread on his 80-acre farm,
- it would reduce odors emanating from the farm, an important consideration for farmers in the urban shadow, and
- it could remove nutrients from the manure, thereby reducing the risk of nutrient overloading on the fields.
Seabreeze started pumping biomethane into the Fortis BC gas pipeline at the beginning of February but this was no overnight project. Planning began almost five years earlier and included a long, often “frustrating” process of obtaining approvals from government and the Agricultural Land Commission. Unique to B.C., the ALC’s mandate is to maintain land for agriculture (the Agriculture Land Reserve). As part of that mandate, it must approve any non-farm uses of land within the ALR and power generation is considered a non-farm use. The ALC also requires that at least 50 percent of the inputs come from the farm itself (this requirement also applies to on-farm processing, packaging and marketing).
Keulen got off easy. George Dick of Dicklands Farm in Chilliwack, B.C., started down the same road about the same time and has yet to put a shovel in the ground.
The process starts with obtaining a power purchase agreement from Fortis BC for gas production and/or BC Hydro for electricity production, then getting it approved by the BC Utilities Commission.
Once BCUC has approved the agreement, the project goes to the ALC and local council. That requires support from the B.C. Ministries of Agriculture, Environment and Forests, Lands & Natural Resource Operations. Dick notes it took him over a month just to complete the nutrient management plan (NMP) the BCMA required. The ALC then hired an independent consultant to review the NMP before even considering his project.
Dick says all parties need a “firm grip on reality” to make AD’s happen.
“We all have to have an ideological shift. All stakeholders need to recognize the value of recovered organic nutrients.”
The Seabreeze system will use 12,500 m3/year of its own dairy manure and about 12,000 m3/year of organic waste from Metro Vancouver’s zero waste initiative and produce enough biomethane for about 1,000 homes.
Solid green waste is mixed with water, then mixed with liquid green waste and dairy slurry and fed into the digester. It spends about 25 days in the digester producing a biogas of about 60 percent methane and 40 percent carbon dioxide. The gas is compressed and fed through a closed-loop water scrubber, which removes the carbon dioxide, harmlessly sending it into the atmosphere.
“We recover 98 percent of the methane,” says Ricardo Hamdan of Greenlane Biogas.
The gas only reduces the original volume by about 20 percent, so there is still a lot of “digestate” to deal with.
That goes to the second part of the operation – a Trident Nutrient Recovery System.
“No AD project is economic without a nutrient recovery system,” says Michael Hellenkamp, business development manager of PlanET Biogas Solutions in Ontario.
Eric Powell of Regenis in Washington agrees, noting the off-farm inputs mean the farm ends up with more nutrients than it started with. Unless something is done about the excess nutrients, an digester actually increases the risk of nutrient overloading in the fields.
Developed in Abbotsford, BC, by Manure Systems Inc. using made-in-North America technology, the Trident system uses a multi-step process to extract the fiber and a concentrated “cake” of nutrients from the digestate. The fiber is dewatered to 35 percent moisture content so it can re-used as bedding for the cows.
The digestate is passed through a diffused air filtration system that uses polymers to capture the nutrients. This then goes through a press which creates a cake, now about one-fifth the original volume, which contains about 85 percent of the phosphate, 50 percent of the nitrogen and 30 percent of the potassium in the original mix.
Initially, the Keulens intend to use the cake to fertilize the field although the eventual aim is to pelletize it for sale off-farm.
After the fiber and the nutrient cake are removed, what is left is a virtually nutrient-free liquid with just 1.5 percent solids, which can be reused as flush water or as irrigation in the fields.
B.C. Environmental Farm Plan advisor Dave Melnychuk believes the there will be many more anaerobic digesters dotting the BC dairy landscape in future.
“I see a great future for anaerobic digestion,” he says. “Nutrient recovery technology offers great potential for the dairy industry.”
BMO senior agriculture manager Steve Saccomano says some projects are showing returns of 10 to 15 percent. As a result, banks are prepared to finance projects “which improve a farm’s efficiency and reduce its environmental impact.” To be considered, projects must be based on proven science, have a sound business plan with contingencies, a long-term supply contract with tipping fees for off-farm inputs and long-term purchase contracts.