The realisation that deforestation and woodfuel shortages are likely to become pressing problems in many countries has turned attention to other types of biomass fuel. Agricultural residues are, in principle, one of the most important of these. They arise in large volumes and in the rural areas which are often subject to some of the worst pressures of wood shortage.
However, residues are often bulky and difficult to burn so various conversion techniques have been developed. One of the oldest of these is briquetting which has been used in Europe since the 19th century to make fuel from low-grade peat and brown coals.
The use of briquetting for conversion of agricultural residues is comparatively recent, however, and has only been taken up in developing countries in the last ten years.
The experience of briquetting agricultural residues has been mixed. Various technical problems have been encountered but the main difficulty has been the fact that, in many places, briquettes are too high in cost to compete with existing woodfuel. However, in some countries, a briquetting industry has begun to develop and find its market niche.
The world-wide experience of briquetting plants is not well-known, either in success or failure. In 1987, the Swedish International Development Agency (SIDA) financed a study of briquetting on a case study basis as well as to review technology and general economics. This report is the result of that study.
The general conclusions presented here are that briquetting plants require some particular circumstances to be successful. There have been more failures than successes throughout the world because of over-optimism about the economic competitiveness of briquetting.
However, in the right circumstances, briquetting plants can make a useful contribution to fuel supply and can be commercially successful. We hope that this report will help to guide people interested in the utilisation of agricultural residues towards the right choices of technology and location and to improve the chances of successful briquetting. We give a list of acknowledgements of people who have helped with the project in Appendix I. We would like to emphasise here the thanks due to SIDA for providing the financial support necessary for the work.