Questions about the project:
Is this a CAFO (confined animal) project? Do the cows spend their entire lives standing/lying on concrete? Or are they allowed time to graze on pasture lands, to lie on soft grass in sunshine or on rainy days?

4600 cows is a huge operation requiring huge quantities of feed. Has anyone crunched the numbers on the sustainability of that feed system... the production of corn and corn silage and the substantial distances that feed must be transported to the central dairy operation? I suspect the cost in terms of tractor/truck consumption of diesel fuel is unconscionable, and that doesn't count the chemical fertilizers and herbicides/pesticides (unless the operation is organic, which I doubt).

What happens to male calves? Are they put into little plastic cages immediately after birth, fed only artificial milk, then 'harvested' for veal? Check it out.

How many times a day are the cows milked? Are they merely machines, or are they treated with respect as sentient beings? I suspect their lives are hellish from start to finish, and that their life-expectancy is much shorter than the cows on the original farm, when the cow population was in the teens.

Big agriculture is unsustainable, and by most environmental measures, immoral. This is big agriculture.

One of the best idea is to convert biogas into renewable vehicle CNG or pipeline gas by installing Xebec Biogas upgarding solution.

An addition to my earlier comment: Please check the conditions of the workers who make this huge dairy profitable. Are they paid a living wage? Are they able to share in the profits they help to generate for the owners? Is on-site housing provided at a reasonable rate, or is it a 'company-store' operation? Are workers' families healthy and living at a reasonable standard? All too often the fantastic growth of agricultural operations comes at a huge cost to the workers who generate the profits (note the history of the kosher meat-packing plant in Iowa as a sad example of what can happen). Also, note the article about offsets on the front page of the NYTimes today (Paying a Bit Extra Each Flight Eases Guilt but Not Emissions by Elisabeth Rosenthal, Nov. 18, page 1A).

Hopefully, the effluent after digestion is going to be used as an organic fertilizer. Also, the exhaust from the generator should have some kind of heat recovery system which can be used to speed up the digestor process. This would increase capacity and/or decrease the size of the infrastructure. Are there other farms in the area that could efficiantly supply additional manure?

Kirk, this is Wisconsin. In the middle of corn country. It's not like the farm's on a rocky atoll thousands of miles from the nearest cornfield -- feed transport costs will be minimal.

Did you even click on the link provided before you did your two comments? You know, this one? http://www.terrapass.com/projects/details/pagels-ponderosa-dairy-biogas.html (Here's another link for you to ignore: http://www.uwdiscoveryfarms.org/corefarms/pagels/index.htm)

[Ed. -- Contact information for the dairy has been removed. Please direct comment period feedback to TerraPass. We're happy to address any questions.]

How about some pics of the dairy, genset, boiler and digester.