A Dung Deal: Making Power from Poop
Larger version of illustration at Globe and Mail
At a properly run farm, "nothing is waste. Everything is a resource. It's just a matter of harvesting." With 750 cows, Laurie Stanton's farm has a lot of manure to harvest. Martin Mittelstaedt writes in the Globe and Mail about Ontario's largest farm-biogas installation. It seems like the perfect solution to a big problem; there are only so many places to put the 50 million tonnes of "biomass", as it is politely called, that is produced each year in the province. Instead, it is fermented in a big tank, and the methane is collected and piped to a diesel generator. The leftover liquids make a good fertilizer and the solids become bedding for cows.
It is about time; in Germany, biogas produces as much energy as a large nuclear plant; here we just build mountains of manure. From the Globe and Mail:
HOW WILL IT WORK
The province announced funding for a $5-million anaerobic digestion power plant at Laurie Stanton's dairy farm in the hopes that it will suggest a way of dealing with some of the nearly 50 million tonnes of biomass, or waste residues from plants and animals, that Ontario produces annually. If successful, Mr. Stanton's farm will produce about 1.3 megawatts, enough to power about 800 typical homes.
1. BARN: Slurry of manure is washed and scraped from cow stalls into a series of sewage pipes that run under the barn. The manure is mixed with other food wastes.
2. DIGESTER: The slurry is heated to around 37 degrees and kept at that level for the five days needed for the microbes to decompose the cow dung. This process gives off methane gas, which bubbles through the slurry and is collected at the top.
3. DIESEL GENERATOR: The gas runs to the generator, where it is burned to produce electricity to power the digester and the farm, and to feed into the grid.
4. SOLIDS SEPARATOR: Leftover liquids are used as fertilizer and the solids are strained to make a material to be used as bedding for the cows. ::Globe and Mail
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