ABSTRACT
The present chapter deals with the generation of power and heat from lignocellulosic biomass and other biomass types.
The work considers the most diffused and common pretreatment steps, as compacting and drying, as well as some innovative approaches like torrefaction. The peculiar effects of this last type of pretreatment on the lignocellulosic feedstock are briefly described. The main goal of biomass pretreating is to feed the downstream bioenergy conversion system with a material that meets the specification of the system. This stage is sometimes underestimated or inadequately implemented in commercial plants by entrepreneurs, especially in the case of small-scale unit, with serious consequences on the performances of the plant and therefore on the business of the operator.
As regards biomass conversion and power generation, the following thermochemical conversion process routes are considered: pyrolysis, hydrothermal carbonization, gasification, combustion. These reactors and conversion pathways are normally fed with lignocellulosic biomass.
Anaerobic digestion of organic materials, as well as conversion of vegetable oils in engines, are also reported, given their very high relevance in terms of installed capacity.
The type of internal combustion engines (reciprocating, or gas turbines) coupled with gaseous or liquid biomass-derived fuels are described, together with their ability to couple with the physical and chemical characteristics of this bioliquids or gaseous biofuels, summarizing the key differences and peculiarities of the two systems.
The basics of biomass gasification are then given, together with the fundamentals of fixed and fluidized bed reactors design.
Combustion of biomass is also reported, given the large impact of these systems on the overall volume of bioenergy generation: these units are normally coupled with steam or ORC cycles for power generation.
Similarly, biogas (anaerobic digestion) is introduced, providing main elements of the chain and the energy conversion process, gas composition and upgrading.
