Foreword

Biogas plants have become something of a permanent fixture in Technical Cooperation between the Federal Republic of Germany and partners in developing countries. Dating back to 1977, the first such projects were incorporated into cooperative efforts with Indian and Ethiopian organizations. At about the same time, the first GTZ project dealing solely with the transfer of biogas technology and the construction of biogas plants was launched in Cameroon.

In the meantime, GTZ has assisted in building and commissioning several hundred biogas plants in Asia, Africa, South and Central America. While most of the systems, in question are on a small scale intended to supply family farms with energy and organic fertilizer, some large-scale systems with the capacity to generate more than 100 m³ of biogas daily have been installed on large stock farms and agroindustrial estates.

In general, biogas technology is for rural areas. In addition to generating energy, biogas systems help stimulate ecologically beneficial closed-loop systems in the agricultural sector while serving to improve soil quality and promote progress in animal husbandry. Consequently, the promotion of biogas technology is regarded as an integral part of technical cooperation in rural areas and, hence, as a key sector of development cooperation on the part of the Federal Republic of Germany.

Within the GTZ, biogas activities center on

- the Biogas Extension Program (GATE), with interdisciplinary teams of extension officers presently working in four different countries:

- the Special Energy Program (Mineral and Energy Resources Division), with rural energy-supply projects now ongoing in ten countries, and

- projects engaged in by Division 14(animal production, animal health and fisheries), within which the importance of biogas technology as a flanking measure in animal husbandry is steadily increasing.

By concentrating the engineering and operational experience gained in numerous biogas projects, this handbook is intended to serve project practicians and advisors as a valuable practical guideline with regard to technical, agricultural and socioeconomic aspects.

Deutsche Gesellachaft fur Technische
Zusammenarbeit (GTZ) GmbH

Authors' Foreword

Biogas plants constitute a widely disseminated branch of technology that came into use more than 30 years ago in Third World countries. There are hundreds of thousands of simple biogas plants now in operation, and each one of them helps improve the living and working conditions of people in rural areas.

While this guide deals only with biogas systems of simple design, the technology is nonetheless sufficiently complex and rewarding to warrant one's close attention to its proper application, planning and construction. The only good biogas system is a well-planned, carefully executed and properly functioning one that fulfills its purpose.

This guide addresses the planners and providers of stock-farming and agricultural-extension services in developing countries. It is intended to serve as:

- a source of information on the potentials of and prerequisites for biogas technology,
- a decision-making and planning aid for the construction and dissemination of biogas plants
- a book of reference for information on practical experience and detailed data.

While consulting experts, extension officers and advisors with little experience in biogas technology will find this guideline useful as an initial source of information, biogas practicians can use it as a hands-on manual. The tables and engineering drawings contained herein provide standard values for practical application. They were compiled from numerous extraneous and proprietary works of reference and then modified as necessary for practical use. The informational content draws chiefly on the latest know-how and experience of numerous associates involved in the various biogas projects of the GTZ Special Energy Program and the GATE/GTZ Biogas Extension Program, of L. Sasse and a great many Third World colleagues and, last but not least, OEKOTOP's own project experience.

We would like to take this opportunity to thank all of our colleagues for their cooperation and the constructive criticism that attended the writing of this handbook. Our appreciation also to GATE and the GTZ division Animal Production, Animal Health and Fisheries, who made this guideline possible. Special thanks also to Klaus von Mitzlaff for the section on gas-driven engines and to Uta Borges for her special elaboration of the aspects economic evaluation, social acceptance and dissemination.

We wish every success to all users of this guide. Feedback in the form of suggestions and criticism is gratefully welcomed.

The OEKOTOP Authors