Investigation of woodchip quality: Relationship between the most important chemical and physical parameters

•An evaluation of woodchip quality employed by power plants and CHP.•Ash and moisture contents variability is highly linked to net calorific value.•Ash content limits are in line with the chemical parameter limits (ISO 17225-4).•The quality classes of woodchip can be divided on the basis of ash.

Considering the global warming and the climate change of the past few decades, European public policies have been established in order to increase the share of renewable energy sources. In the European context, one of the most interesting alternatives is woodchip. The present investigation provides an evaluation of woodchip quality underlining the relationships between the most important chemical and physical parameters, in particular between ash and some elements. Results highlight that the quality of woodchip is good even if some samples have very high ash content. Statistical analysis demonstrated that ash and moisture contents are highly linked to the net calorific value and a specific regression equation (R2 = 0.983) has been identified. Considering the chemical characteristics, statistical analyses pointed out the correlation between elements and ash content demonstrating that the quality classes of woodchip can be reasonably divided based on ash content.