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.