From the article:
Wood gasifiers played an important role in the past in the substitution of oil-based fuels in internal combustion engines, but fell into disuse after the Second World War because of their economic and technical disadvantages as compared with relatively inexpensive imported fuels.
Since the middle of the 1970's the increase in oil prices has led to a renewed interest in wood gasification technology, especially in countries dependent on oil imports but with adequate supplies of wood or other biomass fuels or, as in the case of Sweden, where the technology is maintained and developed as a matter of policy.
Research into the technology of gasifier/engine systems has provided modern designs which work reliably at a level of technical skill appropriate to rural applications in developing countries. Such systems are economic in certain conditions found in many developing countries, but the technology and manufacturing facilities are not widely available and their commercial utilisation is limited.
In "Wood Gas as Engine Fuel" FAO presents a summary of modern wood gasification technology and the economics of its application to internal combustion engines. Texts on different aspects of wood gasification, prepared by specialists, are the basis of this publication.