5.2 Biomass conversion to heat and electricity

This chapter discusses the generation of heat and power from biomass, combustion and gasification of biomass in detail. Two fuel properties, namely the diversity and inhomogeneity of biomass, cause severe technical challenges. Inhomogeneities and contamination with inorganic materials are the main reasons for operational failures and damages of fuel feeding systems. The efficiency of biomass combustors depends mainly on the mass flow, the composition and the temperature of the exhaust flue gas. Neglecting further losses (incomplete combustion, radiation losses, ash losses) leads to a simplified correlation for the efficiency of a combustion system. Combustion calculation also provides the flue gas composition and emission rates. The chapter tabulates elementary composition and heating values of biogeneous wastes, woody biomass, herbaceous biomass and other biomass. Volumetric heating value of solid biomass, lower heating value for gaseous fuel, ash melting behavior, digestion efficiency, gas yield of biogas from dry biomass substrates and economic data of biomass are also illustrated.