Poop Power ?

As I continue my research into the world of renewable energy sources, I find information that is interesting, informative, and sometimes quite amusing. In a previous post, I explored how Jean Pain used the anaerobic digestion of compost to create methane gas - AKA Natural Gas. So I started to look at ways in which the principles of permaculture could be applied. Permaculture refers to finding ways to mimic how Mother Nature achieves her needs.



The best anaerobic digester of organic matter is the rumen ( the first chamber of a cow's stomach ). The cow macerates the cellulose fibre, and when it enters the rumen, it begins to get digested by the bacteria in the cows rumen. The process is helped by the lack of oxygen (making the process anaerobic), and the natural body temperature of the cow.

As we saw in Jean Pain's experiments & feats of engineering, one by-product of the process is methane gas. A ruminating cow will burp up some 280 litters of methane gas every day ! When you consider that there are estimated to be more than 100 million cows in North America alone, this represents an incredible portion of the greenhouse gases emissions which are blamed for global warming.

Unfortunately, this gas would be remarkably difficult to capture. Fortunately, there is still a considerable amount of undigested material passing through the rest of the cows digestive tract, mostly owing to the fact that a cow will digest it's food over the course of about 24 hours. Harvesting methane from compost takes about 21 days. So that undigested organic material can still be processed - provided you are not squeamish about cow dung !



Each one of those cows produce some 28 pounds of manure - every day !
So a herd of 1800 head of cattle will produce 48,000 pounds of manure a day. Certainly more than enough to keep a commercial anaerobic-digestion facility busy. And further fermenting the semi-digested material would have the additional benefit of reducing the unpleasant odours caused by the poop.

The composting rig that Jean Pain built was perfectly suited for finishing off the digestive process. It was sealed, meaning no oxygen could destroy the process, and the capture of methane gas couldn't be easier. Also it was warmed by the material composting in the heap piled all around his fermenting vessel.



When his compost is complete, both inside & outside the anaerobic digester, the by-products are nitrogen-rich soil, and a slurry form the digester. When pressed, the slurry is separated into liquid & solid materials. The solid materials can be recycled back into bedding for the cows. The liquid is a rich fertilizer for use in the fields.

The system has by-products which further support the process: rich hummus to grow new vegetable matter; fertilizer to speed that growth; plentiful feed for the cattle; and plenty of poop to harvest methane from before starting the cycle all over again. In much the same way as Mother Nature intended.

The opinions expressed in this post are purely those of the author. Opinions are like noses; everyone has one and they are entitled to it !