Combustion quality of biomass: practical relevance and experiments to modify the biomass quality of Miscanthus X giganteus.

摘要

A catalogue is presented of quality characteristics relevant for the combustion of biomass to be used as solid fuel. The practical relevance of these characteristics is discussed. The main characteristics are moisture content, the concentration of chloride and ash, the heating value and the concentration of volatiles and remaining coke. Further quality criteria are the concentrations of N, S, K and Ca. In multifactorial field trials in 1991-93 at 3 sites in S. Germany, the effects of site, N and Kfertilizers and harvesting date on the quality of M. X giganteus [M. sinensis] biomass from 3- and 4-year-old plantations was tested. The concentrations of water, minerals and ash, all three of which should be as low as possible, were higher in biomass from a cool, damp site than in biomass from a warm site. The application of K fertilizer led to increases in the ash and K concentrations. Harvesting in February instead of December led to an improved biomass quality because the concentrations of ash, minerals and especially of water had declined. Compared with other lignocellulose plants, M. X giganteus biomass has a very good combustion quality. In February the stems had a water concentration of only 16-33%. The mineral concentrations were also low, with 0.3-2.1 g kg-1 for chloride, 0.9-3.4 g kg-1 for N and 3.7-11.2 g kg-1 for K.