Thermochemical technology, biomass pyrolysis

Biorefineiy is the process of extracting valuable chemicals and polymers from biomass. The main technologies to produce cheiuicals from biomass are (a) biomass refining or pre-treatment, (b) thermochemical conversion (gasification, pyrolysis,... 

The present chapter discusses aspects, known by the authors, of (a) biomass as feedstock, (b) the concept of bio-refinery, (c) thermochemical routes from lignocellulosic biomass to fuels, and (d) the contribution of catalytic technology. The main focus will be on the catalytic conversion of fast pyrolysis oil into fuels with regard to problems encountered currently and the challenges for future research and development. 

The main drawback with the thermochemical route for biomass utilization is the strong dependence on scale-up. To be competitive, the capacity has to be of the order of a small oil refinery (approx. 1 million tonnes per year), but there then exists the problem of the cost of transporting the biomass relatively long distances to this production capacity. Pyrolysis or related technologies ( flash or fast ) could transform biomass into liquid products that are more easily transported, and these liquid products could then be the input for a large, centralized... 

Pyrolysis of biomass is a thermochemical conversion technology of solid biomass into a liquid ( pyrolysis oil , bio-oil ). This liquid can be used as a fuel with properties comparable to (crude) mineral oils. The pyrolysis process itself is not subject to this paper, the technology is described in (6), where there is also given a equation for calculating the cost of the pyrolysis oil depending on plant size and feedstock price. 

There are a number of technologies available to convert the biomass into different energy prodnets and these technologies can be classified into thermochemical processes (combustion, gasification, and pyrolysis) and biochemical processes (digestion, fermentation, and enzyme). As the biochemical processes are normally operated in solutions, me of the biomass is not a control parameter. Therefore, this chapter will focus on the thermochemical processes where the biomass me has direct inflnence on the conversion efficiency and the energy product quality. 

The University ofWaterloo continued the development in greater detail and showed from an economic evaluation that the process is an interesting alternative for the conventional production of ethanol. " In 1999, they compared the cost of producing ethanol from ceUulosic biomass via the hybrid thermochemical biorefinery approach, to acid hydrolysis and enzymatic hydrolysis technologies. The results indicate that the production cost of ethanol via the fast pyrolysis-based concept is competitive with the production cost via the conventional approaches. 

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