How Wood Fuels’ Quality Relates to the Standards: A Class-Modelling Approach

Michela Zanetti,Rosa Greco,Giovanna Ottaviani Aalmo,Stefano Grigolato,Raffaele Cavalli,Corrado Costa

doi:10.3390/en10101455

Abstract

The quality requirements of wood biofuels are regulated by a series of harmonized international standards. These standards define the technical parameter limits that influence the quality of solid biomass as a fuel. In 2014 the European reference standard for solid biofuel was replaced by the International ISO standard. In the case of wood chips, the main difference between the European and International standards is the definition of particle size distribution classes. In this context, this study analyses the quality of wood chips and its variation over the years according to the “former” (EN 14691-4) and “in force” (ISO 17225-4) standards. A Soft Independent Modelling of Class Analogy (SIMCA) model was built to predict the best quality of wood chips and to clarify the relationship between quality and standard parameters, time and changes in the standard regulations. The results show that, compared to the EN standards, classification with the ISO standards increases the samples belonging to the best quality classes and decreases the not classified samples. Furthermore, all the SIMCA models have a high sensitivity (>90%), reflect the differences introduced to the quality standards and are therefore suitable for monitoring the quality of wood chips and their changes.

Highlights

In a context where energy demand is increasing fast and the availability of fossil resources is decreasing [1,2], solid biofuels represent a sustainable energy source
When comparing the European standards (EN) and International standardization rules (ISO) standards from 2013 to 2015 (Figure 1), the slight increase in the number of samples belonging to classes A1, A2 and B and the decrease in number of samples classified as not classified (NC) are related to the classification according to the new ISO standard
The quality classification of wood chips has changed according to the new ISO classification

Summary

Introduction

In a context where energy demand is increasing fast and the availability of fossil resources is decreasing [1,2], solid biofuels represent a sustainable energy source. The production and use of solid biofuels, and woody biomass, can help reduce the production of greenhouse gases (GHG) thanks to their close-to-neutral carbon emissions [3,4]. They can be stored and used when needed [5]. Depending on the biomass preparation process, different types of solid wood-based biofuel are available: firewood, wood chips, pellets, briquettes and charcoal. Compared to pellets and briquettes, wood chips and firewood are a minimally processed material, so their production chain has less impact on the environment than other fuels [6,7].

Objectives

Methods

Results

Conclusion