The importance of accurate measurement of comminuted logging residues’ moisture contents for small-scale forest owners

Bioenergy from logging residues is an important contributor to Swedish energy supplies. Thus, accurate measurements of delivered logging residues’ energy contents are very important for both sellers and buyers. Deliveries’ energy contents are highly correlated with their moisture contents, and thus are determined in southern Sweden (and elsewhere) by measuring their masses and moisture contents. There is insufficient knowledge, however, about the variation in moisture content within and between deliveries, and hence the minimum number of samples needed to obtain the required precision. Thus, these variations were examined in detail in the presented study. Nested analysis of the variance of the acquired data shows that at least nine samples are required to obtain estimates of a delivery’s moisture content with a 3% margin of error. For high volume trade, such as that between forest companies and the energy-conversion industry, current measurement practices are sufficiently accurate. For private forest owners making single deliveries, however, higher precision is required as inaccurate measurements can strongly affect prices.