Biomass quality control in power plants: Technical and economical implications

The consumption of forestry biomass for energy uses is a promising alternative to fossil fuels since it provides different environmental, economic and social benefits to the countryside. A cost-effective methodology is presented in order to establish the biomass price, consistently with its quality. The methodology commonly used in power plants is based exclusively on its estimated heating value, calculated from reference data and measured moisture content. This work analyses the economic benefits of using more accurate heating values determined from other biomass properties, thus requiring additional analyses. Results show that the biomass ash content is the most significant parameter affecting the heating value (a decrease of 760 kJ/kg has been obtained for an ash content increase of 3.7% with respect to reference fuel). The rest of parameters studied (harvesting season and biomass origin) lead to differences below 575 kJ/kg. Considering the increase in the fuel cost from additional analysis, the methodology based on measuring the higher heating value and the moisture content is the most appropriate technique to optimize the cost-benefit ratio of the plant. This technique is even more cost-effective when the frequency of analysis is reduced and the laboratory is shared with other plants from the same company.