Comparative Life Cycle Assessment of Bioenergy Production from Different Wood Pellet Supply Chains

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.

Assessment and Sustainability of Logging Operations in Calabrian Pine High Forests

“…Several authors consider the weight of the produced biomass [32,33] or the amount of energy that can be obtained from it [34] as functional unit. Other studies use the volume of harvested biomass [35,72], with González-García [35] showing that about 40% of GHG emissions (approximately 14 CO 2 eq kgm −3 ) can be attributed to wood harvesting phase, while Valente et al [72] consider the biomass for energy use.…”

“…Several studies dealing with the environmental aspects of forestry operations have been performed. Some of them were limited to Greenhouse Gas (GHG) emissions assessment [29][30][31]; others focused on a single phase instead of the whole cycle within the system boundaries [32][33][34][35] or referred to logging operations realised in different geographical contexts and work conditions [36][37][38]. Indeed, Badraghi et al [39] report the impacts of small-scale wood logging by mules in the mixed broadleaved mountain forest; Proto et al [6,40] compared three different extraction systems concerning the valorisation of forest residuals; Gan et al [41] analysed log harvesting from three types of natural forest.…”

Quality assessment of pellets and briquettes made from glued wood waste

“…Table 6 compares the main technologies and the critical parameters for the production of pellets and briquettes, the data have been extrapolated from Tumuluru et al (2011) and another recent review by Kpalo et al (2019). As reported by Mobini et al (2013) and Sgarbossa et al (2020), the higher cost in energy consumption and CO 2 equivalent emissions for the production of solid biomass (pellets) is due to the drying process. Another process phase that could influence the cost and the environmental impact of densified biofuels is the transport (Pierobon et al 2015).…”

Long-Term Sustainability Approach in Road Traffic Noise Wall Design

“…Previous studies have shown that the CO 2 -eq emission factors of manufacturing concrete components for the analysed noise walls are as follows. The CO 2 -eq emission factor for wood chips produced from roundwood logs is 7.9 g CO 2 -eq/kg [88], that for expanded clay aggregates amounts to 320 g CO 2 -eq/kg [59], and that for mechanically pulverized scrap tires amounts to 122 g CO 2 -eq/kg [84].…”