The beauty of using biodigesters for cooking fuel us that it is low tech.  Low pressure gas, no compressor, no expensive and dangerous high pressure storage system.  

And as you point out Ana, it replaces very expensive petroleum based cooking gas. And the liquid fertilizer substitutes for petroleum based fertilizer.  

Here in Wisconsin, farmers recycle the bedding material after it goes through the digestor.  In these operations the biogas is used to generate electricity that is sold to the utility company.

But it's a high technology, expensive system that adds to the debt load faced by small farms that are desperately trying to compete with heavily subsidized corporate agri-business.

This effort really shows how the environmental movement can partner up with people trying to escape the bonds of poverty by going straight to sustainable technology.  It's great that this project substitutes low tech biogas for mega-corporate propane.

Biofuel from the waste stream, especially from manure that otherwise pollutes the watershed, is one of the applications of technology that actually deserves subsidies.

Biofuel from crops like corn and switchgrass are pork barrel boondoggles, used by politicians to buy votes and get payed off with kickbacks from agri-bizz criminal conspiracies (disguised as legitimate businesses)like Archer-Daniels Midland.

http://amazngdrx.blogharbor.com/blog

It was a very lawyerly (sophistic) op/ed Tom.

Lumping manure combustion and heavily subsidized feedlot agri-bizz digestors in with the use of digestors on small farms.

The farmer that had to double his herd to make the digestor/electricity project work is a victim of missapplied technology.

The better small operation design would sell the natural gas from the digestor to the utility company, thus avoiding the expense of electrical power generation equipment.  But of course that would take government action to get utilities to accept biogas, going directly against the grain of corporate bribery.

The concrete digestor tank is the inexpensive part of the system.  The soaring price of natural gas makes selling the gas the cost effective investment for small farms.

The slurry coming out of the digestor is a great  liquid fertilizer, with much of the offensive odor eliminated.  If you have ever experienced life next door to a farming operation that spreads raw manure on fields you will understand my point.

Solar cogeneration  should be used to recycle most of the water in the slurry.

But the very best application of this technology would be to use direct fuel cell/microturbine  cogeneration to facilitate distributed power generation, putting small farms into the energy business at 75% efficient power generation versus the 30% that utility plants use natural gas.  And the 20% efficiency of the internal combustion electric power from present farm based biogas electric power.

That way even small operations would be cost effective without subsidies.  But with subsidies going to corn/ethanol and oil companies instead of the development of direct fuel cell/microturbine cogeneration systems, that will be a long time coming.

That 75% efficiency changes the economic equation in favor of small operations.

http://amazngdrx.blogharbor.com/blog

Good answers from both Ana and Dr X. I'm convinced about cycling small-scale pig manure into on-farm cooking gas and fertilizer. Less convinced about--but open to--the idea of small farms producing natural gas for sale to utilities. The more interesting approach remains keeping animal production on a small enough scale to recycle manure into the soil.

Eco-tourists who actually help install systems like this, then go home and put a biogas cooking system outside their own kitchgen/garden or a solar panel on the roof to charge their laptop batteries are making personal connections that bridge the boundaries of poverty and nationality that are routinely exploited by corporate/government power to keep us all oppressed.

Wether you are the family in the country invaded  that loses a loved one,or a US family who has your loved one killed as a soldier in war for empire; once the families are one through personal contact like this, it is just that much harder for corporate empire to con  citizens here into ok'ing another invasion.

JFK's Peace Corps style policies in the form of green powered eco-tourism.  There's the enviro-poverty fighting connection.

http://amazngdrx.blogharbor.com/blog

Agreed there are some major environmental offenders in Agriculture, but I believe offenders are a minority across the US farm base.  For example the farms I am working with in Vermont are very interested in protecting the environment we all share.  All of the farms thus far have proven to be strong environmental stewards, and they are looking to anaerobic digesters and renewable energy production as a means to reduce farm odors, to reduce pathogens in the manure, reduce weed seeds so they can cut down on herbicide use, change the manure nutrient chemistry so liquid manure can be applied to growing crops, and to offset fossil fuel purchases for heat and hot water on the farm among other fringe benefits.

One concern I have with the author of the Times editorial opinion is that she lumps direct combustion of animal waste, such as poultry litter, and conversion of animal waste to biodiesel in her argument against farm waste to energy projects.  These technologies are not widespread in the US, and I only know of one poultry waste combustion plant in the country.  She touts the negative environmental impacts of a variety of technologies as evidence that farm waste to energy is a bad thing for America.  The fact is there is a growing farm population that is utilizing anaerobic digestion to effectively address the environmental concerns she raises in her article.  

The author talks about how subsidies are hurting the family farm.  In Vermont, all we have are family farms, even if they have 2,000 cows!  And the economics are changing so rapidly that the 2003 University of Minnesota work cited in her article reveals assumptions which are 300% out of synch with current economics, particularly here in Vermont for cost effectiveness.  Economic cost effectiveness improvements are one consequence of the subsidies critisized by the author.