# Review on Fast Pyrolysis of Biomass for Biofuel Production from [PERSON]
## 3 Biomass Generalities  
### The Dry Process  
The term \"biomass\" refers to all organic matter. This can include matter of vegetable (microalgae included), animal, bacterial or fungal (mushrooms) origin, which can be transformed into energy. The biomass is present in three forms, with very different physical characteristics: solids (for example, straw, plants, leaves, etc.), liquids (for example, vegetable oils, bio alcohols) and gases (for example, biogas. Produced from organic material undergoing anaerobic digestion, biogas is a combination of methane and carbon dioxide. Although commonly associated with biomass, it is actually a result of the fermentation of biomass and is not considered biomass gas) [9].  
Energy derived from biomass is a renewable energy source that depends on the cycle of living plant and animal matter and is an energy born of the sun's action through the phenomenon of photosynthesis [10]. This energy is reserved in the form of organic carbon, and its valorization requires specific processes according to the component used. Depending on the type of biomass and the technology used, the energetic valorization of the organic matter allows for producing three types of energy: the driving force for displacement, heat, and electricity [11]. According to the above, there are three methods of biomass valorization: the dry route, the wet route, and the production of biofuels.  
The dry route of valorizing biomass mainly consists of thermochemical method; this mode include technologies such as combustion, gasification, and pyrolysis:  
* Combustion is a physical-chemical process producing heat through the complete oxidation of fuel in the presence of surplus air.
* The hot water or steam obtained during combustion is mainly used in industry or in heating networks. This steam can be used in a turbine or a steam engine to produce mechanical energy. The production of electricity and heat from the combustion of biomass is called cogeneration [12].
* Biomass gasification is a technology that uses plant material, bone meal, etc., to produce synthesis gas after a thermochemical reaction. The gasification process takes place in a specific reactor in four successive phases as follows: drying, pyrolysis, oxidation, and reduction [13]. The gasification of biomass is one of the most important thermo-chemical transformation technologies, offering significant potential for the combination of various energy production systems. The gas generated through the gasification of biomass is an ecological alternative to the use of conventional petrochemical fuels for the generation of hydrogen, synthetic biofuels for transport, electricity and other chemical products. Gas from biomass contains CO, H\({}_{2}\), CO\({}_{2}\), CH\({}_{4}\) and H\({}_{2}\)O, together with some organic impurities (tar, light hydrocarbon species) and other inorganic impurities (H\({}_{2}\)S, HCl, NH\({}_{3}\)), depending on the gasification process and operating conditions [14; 15; 16].
* Biomass pyrolysis is the chemical decomposition of organic matter at high temperatures to obtain other products that it did not contain in the initial state; the product is obtained either in the form of gas or in the form of volatile matter. This operation is carried out mainly in the absence of oxygen or in an atmosphere that contains only a little oxygen to avoid oxidation and combustion of the organic matter; this technology does not produce a flame. Another variant of biomass pyrolysis is currently being used to treat contaminated biomass or organic household waste.