Biomass is composed mostly of carbon and hydrogen, varying very little from one type of firewood to another; Most types of biomass have a low ash content, with the exception of rice gravel and bagasse;  It is quite the influence of humidity on the calorific value is important  The carbon content of biomass is less than that of mineral coal or petroleum-derived fuels Mainly composed of lignin, cellulose, resins, water and ash;  Negligible sulfur content;  Low calorific value, between ***0 and ***0 [kcal / kg];  It causes deforestation, forcing the creation of energy forests; Supply and storage problems; Low cost (depending on the region) in relation to oil products.