Investigation on woodchip quality with respect to ISO standards and relationship among quality parameters

Abstract

Considering the ambitious European targets for reducing greenhouse gas emissions the energy production from renewable energy sources is increasing as well as the number of biomass power plants. Biomass is a valid alternative to fossil fuels because it is present worldwide and in different forms. Of course, it is important to assess its quality not only for energy characteristics but also for environmental and operational aspects. In this study more than 1700 woodchip samples have been collected in several Italian power plants and the most important physical and chemical parameters have been analyzed to investigate their quality. These data have been compared with the specification expressed in the recently published ISO/TS 17225-9 technical standard. The results show that the ash content is a fundamental and representative parameter for assessing the biofuel quality and that a certain amount of samples has low quality mainly because of their high ash content. In addition, ANOVA results demonstrated that the quality classes expressed in the standard up to 7% ash content are essential in order to meet the needs of the Italian woodchip market. Beyond the value of 7% in ash content, chlorine, sulfur and nitrogen contents increase significantly with consequences for technical and environmental aspects.