Evaluation of Eucalyptus woodchip utilization as fuel for thermal power plants

Abstract

This paper aims to evaluate the implications of Eucalyptus woodchip utilization as an alternative solid fuel for thermal power plants, highlighting its energy properties, power generation expenses and unit variable costs. Woodchip samples were collected from different sources and a proximate analysis was carried out in order to determine their moisture content, basic and bulk densities, ash content and higher heating value. Then, with these properties, empirical indices of a 10-megawatt thermal power plant were used to simulate the potential woodchip consumption, the forest area needed and the unit variable cost (US$·MWh⁻¹) for each sample. The results indicate that woodchip samples with lower moisture content and improved higher heating value presented: reduced woodchip consumption for the same power generation, decreased generation expenses, reduced unit variable costs and smaller Eucalyptus plantations area needed to supply the woodchip consumption. Greater energy density may result in lower transportation and storage expenses, however, does not indicate better generation performance, since it is influenced by biomass field conditions. All samples obtained satisfactory levels of ash content, which may result in lower emissions of pollutants and superior operational efficiency. Finally, all samples presented unit variable costs below the limit established by the government for participation in the regulated energy market, which might be an economic attraction for this kind of project. Therefore, Eucalyptus woodchip moisture content, higher heating value and energy density are key issues in sustainable thermal power generation, and should be managed by Eucalyptus power plants in order to reach better generation performance and reduced expenses.