All posts by Bob Hamburg

Draco 2 Gallery

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.

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US Systems Gallery

Elsewhere Gallery

China Gallery



View Galleries for: China | India | Elsewhere in Asia

I once heard from a high-level corporate researcher at a 1983 biogas conference that Marco Polo’s writings mention masonry-covered digesters in China. I’ve now seen this claim suggested by couple folks I’ve mentioned it to. I’d certainly like it to be true, but it would be nice to verify through the original Italian source.

It seems most appropriate that China, the land of farmers for more than 40 centuries, is also the area of greatest effort toward thedomestication of anaerobic digestion. For most cases, Chinese implementation of biogas replaces the burning of stalks – which may then be fed to pigs – or pressed coal briquets – with their ecosystem destruction, pollution, and climate chaos implications.

After working with early Chinese-design digesters in central West Virginia in the early 1980s (as discussed in OARS’ Efforts), I was fortunate enough to visit China with a University of Pennsylvania program in 1987. In an attempt to differentiate myself from the usual visitor just observing the multitude of efforts, I carried along a variety of hydrogen sulfide and sulfur dioxide testing materials. With these and great cooperation from very interested Chinese researchers, we were able to document significant kitchen air pollution benefits from AD.

Largely from that 1987 summer visit, I offer the following few images as most notable. While viewing, please keep in mind that efforts have been devoted to a full range of sizes and scales and that, from the early 1960s to the mid-1980s, there were literally millions of experiments conducted with family-scale systems — resulting in many leaking failures but progressing through a couple generations of design and construction techniques.