THERMODYNAMIC MODELING FOR HYDROGEN PRODUCTION FROM BIOMASS AND EVALUATION OF BIOMASS ENERGY TECHNOLOGIES

Compared with fossil fuel, biomass is a clean energy with zero CO2 emission, because CO2 is fixed by photosynthesis during biomass growth and released again during utilization. Due to its low energy density, direct use of biomass is not convenient. Thus, it is necessary to convert biomass to fuel gas, such as hydrogen, which can be used cleanly and highly efficiently in fuel cell. Thermo-chemical gasification is likely to be the most cost-effective conversion process and it is promising technology for renewable hydrogen production by utilizing biomass. Biomass gasification produces a mixture of gases (mainly consisting of H-2, CO, CO2, CH4 and higher hydrocarbons), solids (char) and liquids (aromatic hydrocarbons) known as 'tars'. The relative proportion of each constituent depends on the operating conditions such as temperature, pressure, type of gasifying medium, biomass type; biomass feed rate, heating rate, flow rate of gasifying medium, physical characteristics of biomass such as particle size, shape, surface area to volume ratio and the gasifier design. So far various experimental investigations into gasification of biomass carried out, but the work on thermodynamic analysis is relatively limited. Thermodynamic analysis is very helpful in providing theoretical guidance for optimization of design and operation of biomass gasification system. So, in this work a thermodynamic equilibrium model was used to predict the chemical composition of the products of biomass gasification. Gibbs energy minimization approach was used to determine the product gas composition. The code of MATLAB software was used. Gasifier, the most critical component of any biomass gasification system, was modeled as an equilibrium reactor. Equilibrium calculations were compared with experimental data from literature. Finally investigation of evaluation of biomass energy technologies carried out.