Biomass carbonization technologies

Biomass carbonization is practiced extensively all over the world, with technologies resulting in chars covering a wide range of properties and yields. Although the number of papers published in this area is growing fast, mostly with contributions from Europe, the Unites States, and Brazil, there are very few reviews on the hurdles and challenges of carbonization. Char is mostly used as cooking fuel in developing countries and as a reduction agent for the metallurgical industry in Brazil. Since the 1970s, there has been a lot of interest in producing bio-oil from biomass for transportation fuels, and consequently, fast pyrolysis reactors were developed, scaled up, and deployed. This is an area of great research activity that will not be discussed in this review. More recently, there is a growing global interest in using char as soil amendment for sequestering C to fight global warming. This interest is fueling the development of selective carbonization units maximizing C conversion efficiency. The production of large volumes of cheap chars via selective carbonization could catalyze the growth and deployment of a green C economy resulting in the production of green fuels, green chemicals, and materials. In this chapter, we review old and new carbonization reactor design concepts. Reactions and operation parameters responsible for char yield and properties are also reviewed.