View Full Version : Cow Power

Joe (SoCal)
06-29-2006, 07:07 AM
I just saw this story on CBS this morning. I cant find it on their website but it was fascinating.

A whole farming community producing there own electricity from Cow Poo. One large dairy farm is virtually invented the elusive perpetual motion machine. They have thousands of head of milking cows and the poo is stored in HUGE holding tanks where microbes break it down into pure methane gas that is used to run the whole farm/ cheese factory and visitors center. Amazing.

Although methane gas does contribute to greenhouse gas I think it's a better solution than typical smoke stack forms of electrical production. Hey and it also produces great fertilizer as a by product.

It was amazing to see how LARGE scale the operation was.

From another site


March 25, 2002

Waste Not, Watt Not
"The cow is of the bovine ilk;
One end is moo; the other, milk."
If Ogden Nash were writing this poem today, he might want to add a line or two. In the new millennium, both ends of our bovine friends are under scrutiny but for very different reasons. While governments are trying to figure out how to control cow burping, a significant factor in global warming, cow manure is gaining popularity as one of Earth's greenest sources of electricity.

Many United States farmers already know the meaning of "cow power." They collect the methane given off by fermenting cow manure and use it to generate electricity. The procedure is relatively simple: manure is stored in huge tanks anaerobic digesters which are deprived of oxygen and kept at temperatures of 100F. The conditions are designed to let anaerobic bacteria thrive and do the work of breaking the manure down. The large volume of "biogas" released which contains about 90% methane is piped to an engine which burns the gas and uses the heat energy to generate electricity. The leftover manure is compressed; fluid is drained away and used as fertilizer; and the solids are dried out and used as bedding for the herd and compost.

The method offers a neat solution to the manure waste problem. America's 100 million cattle produce their fair share of manure on Tinedale Farm, in Milwaukee, the 1800 Holsteins produce about 48,000 pounds per day, much of which is processed to generate electricity. By using manure in this way, farmers are transforming problematic waste into new, useable commodities: electricity, compost, and fertilizer.

According to Environomics, a company that manufactures manure-digesters, 32 farms in the United States are using the digesters for electricity-generation. The technology has not been more widely adopted because the systems are expensive to install, costing from $200,000 to $1,000,000 each, depending on the size of the herd. To encourage farmers to generate their own electricity, the state of California's Energy Commission is making $10 million in funding available to support farmers' initiatives. It is currently reviewing about 30 applications for grants and plans to install several digesters by this summer.

06-29-2006, 07:16 AM
I like such stories. And I don't think that the balance of greenhouse gases is affected ... the vegetation digested by the cows grew, taking in carbon dioxide etc., and simply release back into the atmosphere the same constituent bits.

Nothing in this cycle has brought carbon etc. back into the active ecosystem which had previously been removed through fossilization.


06-29-2006, 07:26 AM
or let the cowchips fall where they may, dry in the sun...and burn them for heat to generate steam etc....:D

Leon m
06-29-2006, 07:37 AM
Not to mention there is no mercury byproduct, as in coal burning.

06-29-2006, 07:39 AM
See, in the long run, I think we need to think about keeping thermal power thermal, and mechanical power mechanical. Use wind and tide and solar for electricity. Use biomass for heat.

This kind of technology has been played with for decades, and in India there are villages with digesters that provide cooking gas. Its drawback is that that 10% that's not methane has a lot of hydrogen sulphide in it, which stinks, is poisonous, and corrodes the pipes really fast.


06-29-2006, 08:03 AM
... that 10% that's not methane has a lot of hydrogen sulphide in it, which stinks, is poisonous, and corrodes the pipes really fast.

DanGoogle is my friend. There's a presentation from conference proceedings on small-scale biogas here: http://www.rosneath.com.au/ipc6/ch08/shannon2/index.html which includes instructions on how to make a very inexpensive hydrogen sulphide scrubber. They use a glass demijohn stuffed with steel wool, which corrodes sacrificially much on the same principle as putting zinc anodes on the bottom of your boat. Pipe the raw biogas in through a pipe that goes to the bottom of the demijohn, pipe the scrubbed biogas out through a pipe drawing from the top. Replace the steel wool when what's been stuffed in the glass demijohn shows 75% corrosion.http://www.rosneath.com.au/ipc6/ch08/shannon2/img00003.gif

They also give plans for a small scale lime-spray scrubber, to remove carbon dioxide from the biogas. Not necessary for health reasons (unlike the hydrogen sulphide), but the Co2 percentage tends to be variable, and can mess with the efficient operation of your burning appliance.

Brian Palmer
06-29-2006, 12:53 PM
On a per molecule basis, methane is a more potent green house gas (GHG) than CO2. So capturing the methane in a digester and using it to generate electricity while converting it to CO2 is more efficient in reducing potential greenhouse effects than simply using the methane as a replacement for other fossil fuels.

You will often see a flare at landfills and wastewater treatment plants to burn off methane with no energy recovery simply as a way to reduce the GHG potential of the emissions.

Lancaster County here in PA has several dairy farms with digestors. The farmers are actually making money (like a couple thou $$ a month) selling electricity back to the grid after their in-house needs are met.

- Brian

06-29-2006, 02:02 PM
Unless they're just talking about dairy cows, I'm amazed at the sharp decline in the number of cows in the US. Some years ago, it was 540 million.

Dan McCosh
06-29-2006, 02:06 PM
It is an interesting concept. There are lots of problems being solved here--getting rid of the manure; creating organic fertilizer; making electricity; etc. The carbon cycle itself would take some study, but it looks pretty good. Doesn't look economical in and of itself, but that depends on how it is accounted for. Might note that it would work with any domestic animal. Methane from landfills already powers several auto plants.

06-29-2006, 02:11 PM
Not just animals either ... anaerobic digestion can produce methane from any biomass. Not a bad use for many plant byproducts ... though it's certainly more labour intensive to manage than aerobic digestion.

06-29-2006, 03:31 PM
I bet it could even digest surplus republicans. :D

06-29-2006, 03:38 PM
Many of those are just hot air though.


06-30-2006, 05:15 AM
There was some talk in government circles here a couple of years ago, of introducing a tax on cows because their farts emitted methane and contributed to greenhouse gases.

Ron Williamson
06-30-2006, 05:21 AM
It seems like a good idea for domestic sewage as well.

Joe (SoCal)
06-30-2006, 05:47 AM
Yet anouther clever energy efficient idea.


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