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According to the EPA, there are currently 140 anaerobic digester facilities in the United States that capture biogas on commercial farms and turn it into electricity. South Dakota has one of these lemons-into-lemonade power plants: a dairy near Milbank can turn the waste from 2400 dairy cows into power for 250 homes.
Some quick math: South Dakota currently has 95,000 dairy cows. Pump their emissions into 40 anaerobic digesters the size of the one near Milbank, and we get power for just about 10,000 homes.
Of course, you could get more annual energy output from 40 1.25-megawatt wind turbines like those powering the city of Rock Port, Missouri. But as my friend Tony will point out, you need baseload power, always on. The wind doesn't blow all the time; cows do.
Now all this poop power isn't a lot: at most, all those dairy cows might produce enough waste to power 3% of South Dakota's households. That power would come at the cost of keeping all those critters confined in feedlots. I don't want to bring cattle in off the open range just to collect their solid and gaseous waste. But if we already have all these cattle and hog confinement operations, why not polish the turd and get some electricity out of them?
In the end, electricity from livestock emissions could be a win-win for everybody. We get renewable power, we reduce pollution, and feedlot operators get one more revenue stream. Can't beat that!
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Update 10:30 CST: Ah, but Grant County neighbor Joelie Hicks reminds me of some messy truths shown in these photos which I'm told show overflow from the Milbank manure digester in summer 2008 after a big rainstorm:
You can heat a greenhouse or cold frame with raw manure by shoveling it underneath the structure and letting the waste heat from its decomposition keep the building toasty. But, you need a steady source of raw manure to do this--mucking out the winter stalls is a good way.
ReplyDeleteThe resulting composted manure then becomes an excellent fertilizer.
don't forget that wonderful photo you have of the overflowing manure digester, and that it akes care of only one gas, out of about 90 gasses. not even counting the energy it takes to create and transport one of those expensive digesters.
ReplyDeletejoelie hicks
Thanks for that reminder, Joelie! See photo update above!
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