The Stanton Brothers dairy farm, which has 750 cows, is building the system to turn tonnes of cow dung, normally spread on fields for stinky fertilizer, into methane gas that can be burnt in a converted diesel generator to create electricity.
“It’s the largest on-farm digester in the country,” explains energy consultant Garry Fortune who is helping create the system.
“We’re running material through it in the test phase now, we’re actually producing the byproducts from it.”
Besides methane gas, these byproducts include a nutrient rich effluent that can be used as fertilizer and a peat moss-like fibrous material that will be used as bedding for the cattle. Any surplus will be sold as a peat moss alternative.
A slurry of manure will be piped from the barn to eight three-story “digesters” where it will be fermented by bacteria that break it down. Letting the “bugs” break it down also kills pathogens in the manure and eliminates the odor.
“It’s like a brewery,” said Fortune.
But instead of getting drunk, consumers will get heat and light, up to 1.3 megawatts worth through a deal with the province that will see electricity from the system sold to the Ontario power grid.
That is one reason the province is putting $5 million into the project. Another is to help divert that cow waste — and other off-farm organic waste that will be added into the mix — from going to the landfill.
“We believe it is a more responsible way to deal with on-farm waste,” said Fortune.
The converted diesel generators that will burn the gas will also be cogeneration systems, meaning heat created in the combustion process can be caught and used to heat the facility as well as the digesters that need to be kept at 37 degrees Celsius.
The system requires a balancing act of the right ingredients and the right heat.
“What’s key here is getting your recipe right,” explained Fortune.
“In essence this is like a big giant stomach, you gotta make sure you don’t upset the stomach.”
Fortune said the farm has research partnerships with the universities of Guelph, Waterloo and Western Ontario to look at other projects, such as creating hydrogen. Another idea is to use the effluent to feed algae that can then be turned into biodiesel.
