No abstract

The EU is one of the largest producers and consumers of wood pellets in the world, covering around 36% of the global wood pellet production and around 50% of the global consumption in 2018. The EU wood pellet consumption is expected to further increase in response to the ambitious energy and climate goals for 2030. Currently, wood pellets are mainly produced from sawdust and other sawmill residues; however, other types of forest feedstock are being investigated in order to meet the increasing wood pellet demand and move toward greater energy independence. The aim of this study is to evaluate and compare the environmental impact of different wood pellet supply chains. A comparative cradle-to-grave life cycle assessment is performed considering the following wood feedstock systems: (i) sawdust from sawmill (S1), (ii) roundwood logs (S2), (iii) whole trees from forest thinning operation (S3), and (iv) logging residues produced during forest tree harvesting (S4). The study focuses on Global Warming Potential (GWP), Ozone Depletion Potential (ODP), Photochemical Ozone Creation Potential (POCP), and Human Toxicity Potential (HTP). Results show that S3 displays the lowest figures on all the environmental impact categories considered in this study. Compared to the reference case S1, S3 shows a GWP reduction of 46%, an ODP reduction of 6.6%, a POCP reduction of 14.8%, and HTP reduction of 13.2%. S3 and S4 have lower GWP than S1 and S2, even when the biogenic CO2 emissions are considered. Overall, the life cycle phases that have the highest GWP, POCP, and HTP are the burning phase and the preparation of the material to be pelletized, particularly the drying process. Nevertheless, the main phases that contribute to the ODP are the forest operations and the pellet preparation.

Nowadays many types of biomass are studied to satisfy the increased demand of renewable energy based on pellet combustion. However, only a few biomasses fulfil the high quality standard required for pellet used in domestic appliances. European and International standards in force define this quality of non-industrial use of pellets in term of the origin of biomass, physical, mechanical and chemical parameters. Vineyard residues are a worldwide potential source of energy but their compliance to be used in domestic pellet stoves has not been yet proven according to the new standards in force. In order to meet this need, this study makes an exhaustive characterisation of vineyard based pellets manufactured from residues of Prosecco (Glera variety) vineyards, assessing both the quality of biofuel and its behaviour during combustion in a domestic pellet stove. The quality of biofuel has been evaluated according to the in force standards for wood and non-woody pellets. The results show that vineyard pellets do not meet the type B quality standards required for non-industrial use of wood pellet mainly because of the high amount of ash content (>2%) and the high amount of copper (>10 ppm) but they fulfil the specifications of the type B non-woody pellets. Furthermore, during combustion test of vineyard-based pellet the high emission of CO indicates incomplete combustion; and vineyard-based pellet NOx emissions are more than double compared to those obtained during the control tests, confirming that the analysed vineyard-based pellets are unsuitable, as they are, for use in traditional pellet stoves.

No abstract

The pellet market has experienced a continuous development and increase in recent years due to a number of positive properties of this enhanced biomass. However the supply chain has not been entirely able to follow the same trend, causing some issues, often related to the quality of traded products. These problems can be partially solved by ensuring a continuous and reliable flow of information regarding the quality parameters of wood pellets from the producers to the final users. The aim of this work is to define a metric index for quality parameters that can detect the certifiability of analyzed samples compared with those on the market. The model is built on measured quality parameters of certified and non-certified wood pellet samples taken from products on the market applying a multivariate class modelling methodology (soft independent modelling of class analogy, SIMCA). Results showed that the model can predict the general quality of some test samples and that its precision, already fairly high, can be constantly improved by adding new model samples. The output of the model is also the relative influence (modelling power) of each variable in the prediction of certifiability. The SIMCA model could be easily integrated and implemented on the most common digital platforms where users (private, laboratories, agencies, etc.) could test their samples and verify if the index of their pellet falls within the area defined by the model for certified sample