Agriculture biogas digester leads to happier cows

Published on July 19th, 2012 | by Tina Casey


Cow Power in Action: 920,000 kWh of Electricity and Happier Cows

July 19th, 2012 by  

Last August, the Pennwood Farms dairy farm in Pennsylvania installed a digester to convert the manure of its 570 cows into biogas, and the new equipment is already yielding some extra benefits. Along with producing enough biogas to generate electricity at the rate of 920,000 kWh per year, the digester produces high-quality bedding that makes the cows feel more comfortable. And you know what they say about happy cows…

biogas digester leads to happier cows

Renewable Energy from Biogas

The U.S. Department of Agriculture has been pushing dairy farms and other livestock operations to install anaerobic digesters, which use a natural microbial process to break down raw manure. The microbes produce biogas as they chew their way through the organic material in manure. The gas can then be burned in a generator to produce electricity.

The “leftovers” from the digestion process form a benign (aka less smelly) sludge that can be dewatered and used as a natural soil enhancer in place of chemical fertilizers, or thoroughly dried and used as bedding in stalls.

In addition to producing renewable energy, digesters make for much better manure management than open lagoons, which have become notorious for causing air and water quality problems.

In turn, improved manure management can enable a livestock operation to expand without incurring additional costs for conventional manure disposal or remediation.

That also dovetails with broader public policy goals, such as preventing the contamination of drinking water supplies.

A Cow Power Showcase

Aside from helping livestock farmers to resolve environmental issues efficiently and economically, digesters can also provide farmers with a new revenue stream as illustrated by Pennwood Farms’s experience.

The digester provides all of the electricity for the farm and generates enough excess to sell back to the grid, equivalent to the typical electricity consumption of an estimated 600 people.

The farm also used to purchase sawdust bedding to the tune of $60,000 per year, but now the digester enables it to produce its own bedding on site.

Depending on the type of operation, farms with digesters could also market the dewatered digester sludge as a natural fertilizer.

Of course, a little support from the government helped to get the operation up and running: USDA provided a $264,450 Rural Energy for America Program loan and a $264,574 grant, and the Pennsylvania Energy Development Authority chipped in with $475,274 in funding for the biogas operation at Pennwood Farms.

Biogas, Milk Production, and Happy Cows

The new digester could also help contribute to higher milk production. Just a few months after the digester was installed, Duane Stoltzfus (one of four brothers who owns Pennwood) told a reporter that “the cows are happier because of the higher use of bedding… They use their stalls better and are better health-wise.”

A 2009 study from England provides some evidence to support the notion that contented cows produce milk at a significantly higher rate, though apparently the addition of some nicer bedding is just one of many possible strategies.

According to a recent report, anecdotal evidence suggests that classical music, massages, and a personal name can provide a significant boost in milk production, too.

Image: Some rights reserved by davedehetre.

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About the Author

specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. Tina’s articles are reposted frequently on Reuters, Scientific American, and many other sites. Views expressed are her own. Follow her on Twitter @TinaMCasey and Google+.

  • AgWriter

    Too bad the photo of the cow in the grass misleads the reader to think it is representative of the process. In order to efficiently gather the waste materials and capture the waste, the animals have to be kept on concrete and under roof.
    It is also ironic that more than a million dollars in low-interest loans and grants were provided to “showcase” a technology that is already in place throughout the country. Digesters like the one described are working effectively and economically. In Europe, they are common place. This is a long proven technology and ill-deserving of taxpayer funding. 

  • rkt9

    If it helps reduce the aweful smell, I reckon there will be a lot of happy people who live near these dairy farms as well!  I wonder if they could get the feed lots out west to use this technology?

    • Bob_Wallace

      If it can be clearly shown that herd owners can make (or save) some money with this technology then it will be adopted.

      • Sts

        Sure, all it takes is a million US dollars to try it and see if it works…

        • Bob_Wallace


          That’s a grand contribution from each of us of three tenths of one penny.

          $0.012 for a family of four.  And in return we get another source of renewable energy on the grid.

          Thanks for pointing that out.

          • Sts

            Interesting math.  How do you come by those numbers?

          • Bob_Wallace

            $1,000,000 / 312,000,000 million Americans.

            My calculator faulty?

          • Sts

            Sorry for replying above you, the discussion forum will only embed so many replies.

            Your math isn’t faulty, just your suppositions.  Only 41 million Americans pay taxes so it’d work out to 2.44 cents per taxpayer.  Then we multiply it by the 160,000 dairy farms in the US and we get $3,902 per taxpayer. 

            Regardless of the return on investment, that’s my $3,900 bucks and I don’t want to part with it.

          • Bob_Wallace

            Well, let me look at your assumptions….

            First, I see nothing that says that taxpayers will be paying $1 million for all 160,000 dairy farms.  

            Second, it is highly unlikely that future setups would cost $1 million each, commonly it costs far more for prototypes.

            Third, well this isn’t an assumption. Or perhaps part of it is.

            How about we don’t use any of your tax dollars for poop digesters but  dedicate some extra of your tax money to Mideast and Southern Asia oil wars?  

            We can balance that out by sending less of mine to the oil wars and more to renewable energy projects.

            Nine trillion dollars.  I’ve seen that used as the US cost of three oil wars.  Divide by your 41 million tax payers and that’s $219,512 per tax payer.

            Wish there was a way to directly bill you renewable energy skinflints for the cost of fighting oil wars.  Then, perhaps, you’d catch a hint.

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