Category Archives: USA

United States & Other “Economically Developed Countries”


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AD systems have been a component of many municipal sewage treatment plants in the United States and Europe for more than 100 years with the gas used to reduce external energy requirements. While more industrialized systems for digestion of animal residues were developed in Germany during World War II, it was not until the “oil crises” of the 1970s that broader interest developed. {Indeed, very many of the alternative energy activities so well initiated in the late-70’s in the USA fell to naught under the Reagan revolution and its continuing aftermath.}

Many universities with agricultural mandates developed research programs to investigate the possibilities. As might be expected, most efforts in the US have been focused on large systems producing enough gas to generate electricity. While electricity generation directly from biogas is only about 35 percent efficient, use of engine coolant waters to heat the digester can result in overall efficiency of more than 60%. Unfortunately, many of the university programs lasted only a couple years. This is not nearly long enough to seriously investigate all of the parameters which may affect digestion, gas production, and most especially, overall system potential.)

Many of the earlier digesters suffered from a range ofcommon problems . Many of these remain issues of concern. Nevertheless, there are currently a range of larger-scale agricultural systems operating in the US – [Hey, there are even more than 150 in the US. Sure, there are more than 4000 in Germany – but they’re just stupid krauts (like me).] The EPA AgStar web site is an excellent source of information on these larger-scale systems and AD in general.

While all this was going on at the large-scale level during the 70s-90s, there were many, much less well-funded enthusiasts working to demonstrate the feasibility of smaller back-yard- to medium-scale systems. David House’s Biogas Handbook is quite useful at this level. Unfortunately, a great majority of these systems were fairly short-lived. I suggest that this is largely due to great over-expectations in the amount of gas produced and failure to fully and symbiotically take advantage of the vast range of symbiotic options made available through digestion.

I offer the following images primarily for historical perspective.

Click to view US Systems Gallery

US Systems Gallery