Simple designs for DIY home biogas generation? Answered
A friend of mine is working in Sri Lanka at the moment on a biogas project. Part of the remit is to improve the design of a village-scale rural digester of the "buried concrete tank with a lid" design (as pictured below), by tweaking the operation in terms of feedstock, water:feedstock ratio, temperature and so on.
The other task is "to design an efficient and neat anaerobic digester to market to middle class families." I say "DIY" because making these of simple and widely-available materials is clearly preferable to involving lots of expensive parts.
Collectively we seem to have a good deal of expertise on similar subjects- biodiesel, algae growing and so on, so I wondered if anyone knows enough about biogas to be able to comment on whether a simple design (possibly something like the Appleseed biodiesel processor) could be practical. Any lateral thinking on how to overcome the limitations of small batch processing would also be great.