Effects of Sample Handling and Transportation on the Moisture Content of Biomass Samples

Using biomass in energy production has a significant role in the progress toward carbon neutrality in Finland. In the biomass combustion process, moisture content is an important factor. To enhance efforts for well-quantified uncertainty estimations in reference moisture measurements for biomass, errors related to handling and transporting samples were studied in this work. At the Centre for metrology of VTT Technical Research Centre of Finland, experiments and simulations were carried out on effects of water mass gain and loss when forest biomass samples are transported to a laboratory and prepared for moisture analysis. Results suggest that opening the sample bag may change bulk moisture content considerably and homogenization of the sample with varying moisture contents inside sample bags typically takes weeks. Results with varying thermal conditions show that the moisture content changes in the tested samples were insignificant. Monitoring the masses of samples and sample containers separately is recommended when aiming at high accuracy in the analysis of hygroscopic samples.