It does cover biogas and methane production again as an overview. So there are a number of examples of different scales of systems, like the small scale farm stuff that there are millions of in China, as well as the town sized systems in Germany. Its not a how too guide for the technology but there are lots of good pointers in there in terms of next steps. It mainly focuses on what can be done as a community rather than an individual homestead, but will give you a good overview of whats possible.
A snippet as follows: " In China biogas production began as early as the 1880s. By the 1950s the Government began actively promoting it and today they are actually the world leader in biogas production. It amazes me that over 40 million residential biogas fermenters have been built in China to date. Tens of millions of families use farm and household waste to make clean cooking fuel in these backyard fermenters. Yet only 19% of the potential for biogas potential had been utilized as of 2010 . Germany generates as much electricity as two nuclear power plants with the gas produced by decaying plant matter and animal slurry. Biogas is an old technique applied around the world in low tech and high tech ways to deal with a range of materials that would otherwise be considered as waste problems. However in true alchemist fashion it turns muck into gold, producing a couple of really useful outputs in tackling the waste stream: gas and fertilizer. "
Good luck with it