Characterisation of the most representative agricultural and forestry biomasses in France for gasification
An extensive characterization was carried out on various biomass samples representative of the diversity in France, including forestry samples (softwood and hardwood woodchips, eucalyptus and poplar short rotation coppices), very short rotation coppices (VSRC) samples and agricultural samples (wheat straw, triticale, fescue, miscanthus and switchgrass). The following properties were measured to evaluate suitability with thermochemical process: elemental analysis (C, H, O, N, S, and Cl), chemical composition (extractives, lignin, mono/polysaccharides, acetate groups), ash content and inorganic composition. Carbon and hydrogen contents are quite similar between biomasses. Agricultural biomasses are usually less oxygenated than forestry biomasses. Nitrogen content is generally higher for agricultural biomasses (up to 1.4 %) than for forestry biomasses, but important amount is also found in VSRC (0.8 % for poplar). Chlorine and sulfur are species-dependent. Fescue and eucalyptus show high values of Cl, while wheat straw has the highest sulfur content. Ash content is very low for forestry and perennial biomasses (miscanthus and switchgrass). For non-perennial crops, values up to 8.5 % (wheat straw) were measured. Agricultural biomasses contains more silicon (2 % for triticale), magnesium (0.16 % for fescue), potassium (1.9 % for fescue) and phosphorus (0.18 % for fescue), while forestry biomasses are richer in calcium (up to 0.97 % for poplar VSRC). Other inorganic elements, especially heavy metals are present in very low concentrations and most of the time below detection limits. Regarding chemical composition, extractive content is very high (20–25 %) for non-perennial crops (fescue, wheat straw and triticale) and eucalyptus VSRC. Lignin content seems to be higher for forestry biomasses (21–29 %) than for agricultural biomasses (16–23 %). The same trend was observed for cellulose, while the opposite was observed for hemicelluloses. These differences in organic and inorganic composition are expected to significantly impact the behavior of these biomasses in thermochemical processes such as gasification for biofuels production.