Worldwide, more than 1,000 biogas
production units are now operating or are under
construction. It is estimated that European plants
comprise 44% of the installed base with only 14% located
in North America. Sayigh (1992) reported that biogas is
highly relevant in energetic environment of Brazil as a
tropical country with more than 30 million inhabitants
who depend on wood burning as fuel. As far as 1950,
the fact that biogas was obtained from forest sources
presented a relative reduction in its total production.
The emergence of biogas from sugarcane by-products,
however, made significant contribution to its availability
in rural Brazil.