~--. The qua of liqu°id material should never exceed¾ of • the pit volume· Put in and take out material frequently. When removing slurry for fertilizer. do not let the level fall below the upper edge of the passage to the fermentation compartment from A Chinese Biogas Manual July 1980 RAIN Page 7 1 from A Chinese Biogas Manual removabl.e cover -";~~-· - ,, f'. . .I\\ ,✓,~»t(#.✓, material • 1 outlet1 '/ ' • separatin.g v.vall fermentation. compartment pigsties built above a biogas pit. max has a lot to recommend it as a shutter •material, but that's·some drawbl;!.ck it's got there! Both L~ngdon and Shurcliff note these problems, but each of them tries to go on with'the business of promoting their use .anyway. (It's easy to argue that we are'surrounded by equally dangerous products in all of the plastics, adhesives, etc., with which we fill our homes. Most of these also •give off tQxic gases when they burn. There are no pat solutions.) Langclon actually does less to promote products and more to promote self-reliance. Many of the .curtains he describes were designed and fabricated by community groups and local self-help enterprises. He pays credit to these in one of his Appendices. He also provides details for constructing three of the models he describes and lists sources for many other sets of plans so you can save a bundle by making your own. -CC Windows, free from: Energy Efficient Windows Program c/o Stephen Selkowitz Bldg. 90, Rm. 311_ . Lawrence Berkeley Laboratory i Cyclotron Road • 1 Berkeley, CA 94720 The Lawrence Berkeley Lab is managing POE's Energy Efficient Windows Program. They offer this magazine to 11 accelerate exchange of information1 ' recognizing that much of the technology has been developed but needs to be communicated. A magazine is much more immediate for this sort of transfer than a book would be. Besides, it's free·and therefore more accessible to everyone. In this issue several window insulating • products a.re described (some clear enough you can make your own), legislation pertaining to energy efficient window systems is outlined, and there are lists of reference materials to turn to. Send for your copy. -CC I -c BIOGAS A Chinese Hiogas Manual, translated from the Chinese by Michael Crook, edited by Ariane van Buren, 1979; 135 pp., $11.95 from: ISBS, Inc. P.O. Box555 Forest Grove, OR: 97116 Available overseas from: Interm~diate Technology Publications Ltd. 9KingSt. London WX2E 8_HN England This book presents a sharp contrast to biogas books written in the West: The Chinese have made biogas work throughout the rural provinces, and they have done it mostly without electricity, mechanital feeders, agitators, pumps, piping, metal containers, or external heat sources. Build.: ing the digesters involves using local mate- . rials and labor intensive construction technique~. They_ run their digesters on local waste plant materials and local animal manure (in many instances they build chutes directly from the barns to the digesters). The digesters themselves are buried to tap into the relatively constant ground temperatures. Caring for the biogas pits and their contents is done entirely by hand. You should read this book even if you . don't want to build a biogas generator just to see a very different approach to A.T. Biogas in China is a luxury (as a cooking fuel and as a source of light) as well as a means to control the spread of disease which traditiorrally has been transmitted by 1 nightsoil. For us, it is a return to an aware-, ness of the cycle of living organisms. - • Gail Katz Metha-,ie.Digesters for Fuel Gas and Fertilizer, The New Alchemy Institute, • Newsletter #3, Spring 1973, 47 pp., • $3.00 from: . The New Alch~my Institute P.O. Box47 Woods Hole, MA 02543 This book helped start the wave of interest in biogas production in America. It is ~till the best basic introduction if you're toying ~ith the idea of building a methane digester, but don't know if it's right for your situatio~. You'll learn what you need to • put into a digester and what you can expect to get out. -=-Gail K?,tz . , The Comple at Riogas H~ndbook, by d. house, 1978, 400 pp., $8.00 ($9.00 outside the U.S.) from: • • • At Home everywhere, c/o VAHID, Rt. 2 • Aurora, OR 97002 - Please write to._the attention of Rita Dog for quantity prices and special discounts Once you've decided to build a methane digester and want to know all the details of putting one together, you should read this book. It is a basic, step-by-step description-what happens (and what can go wrong) in the digester; what you.need t'o do to the mixture; how to decid~ what to put in a'nd what not to; how to u~e the gas; advice on various decisions that will have to be made; how to trouble-shoot; and discus-' sions of equipment and designs. The · author's bias is towards a highly efficient, mechanized system, but he has included enough basic information'on all types of systems that the book wiJl serve as a useful source of information no matter,which way you decide to go. -Gail Katz
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