Journal of Energy Bioscience 2024, Vol.15, No.3, 147-159 http://bioscipublisher.com/index.php/jeb 150 4.2 Pyrolysis 4.2.1 Process description Pyrolysis is a thermochemical process that decomposes organic materials at high temperatures (300 °C~900 °C) in the absence of oxygen. This process results in the production of bio-oil, syngas, and biochar, which can be used as energy sources or soil amendments (Dutta et al., 2021). 4.2.2 Types of pyrolysis reactors There are several types of pyrolysis reactors, including fixed-bed, fluidized-bed, and rotary kiln reactors. Each type has its own advantages and limitations in terms of efficiency, scalability, and product distribution (Yang et al., 2023). 4.2.3 Bio-oil, syngas, and biochar production The pyrolysis process yields three main products: bio-oil, syngas, and biochar. The distribution of these products depends on the pyrolysis conditions, such as temperature and heating rate. Bio-oil can be used as a liquid fuel, syngas as a gaseous fuel, and biochar as a soil amendment or carbon sequestration agent (Dutta et al., 2021). 4.3 Gasification 4.3.1 Process description Gasification is a thermochemical process that converts organic materials into syngas (a mixture of CO, H2, and CO2) by reacting the material at high temperatures (800 ℃~1200 ℃) with a controlled amount of oxygen or steam. This process is highly efficient in converting biomass into a versatile energy carrier (Ajay et al., 2021). 4.3.2 Syngas production and applications Syngas produced from gasification can be used for various applications, including electricity generation, chemical synthesis, and as a fuel for internal combustion engines. The composition and quality of syngas depend on the feedstock and gasification conditions (Dutta et al., 2021). 4.3.3 Factors affecting gasification efficiency The efficiency of gasification is influenced by factors such as feedstock properties, gasification temperature, and the type of gasifying agent used. Optimizing these parameters can enhance syngas yield and quality (Dutta et al., 2021). 4.4 Combustion 4.4.1 Direct combustion techniques Direct combustion involves burning organic waste in the presence of excess air to produce heat, which can be used for electricity generation or industrial processes. This is the most straightforward method of energy recovery from biomass (Ajay et al., 2021). 4.4.2 Energy recovery systems Energy recovery systems, such as combined heat and power (CHP) plants, can improve the overall efficiency of combustion processes by capturing and utilizing the heat generated during combustion (Ajay et al., 2021). 4.4.3 Emission control measures Emission control measures, including the use of scrubbers, filters, and catalytic converters, are essential to minimize the release of pollutants such as particulate matter, NOx, and SOx during combustion(Ajay et al., 2021). 4.5 Bioethanol and biodiesel production 4.5.1 Fermentation processes Bioethanol production involves the fermentation of sugars derived from biomass by microorganisms, typically yeast. This process converts sugars into ethanol and CO2. Biodiesel production, on the other hand, involves the transesterification of fats and oils to produce fatty acid methyl esters (FAME) and glycerol (Ajay et al., 2021).
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