Dra. Azócar-Ulloa, Laura

The use of pellets as a replacement for firewood has been promoted in Chile to mitigate atmospheric pollution. However, their high demand has generated stock shortages, which has motivated the search for alternative sources of feedstock. Furthermore, invasive shrubs are a highly available biomass source for bioenergy production in central-southern Chile and may be a significant factor contributing to the spread and increasing virulence observed in wildfires across the region. This study aimed to determine the change in wildfire indicators related to the removal of invasive shrubs in selected zones in the Biobío region and to assess the physicochemical properties of the extracted biomass to develop a pellet formulation to produce a material conforming to ISO standards. The biomass management of Teline monspessulana, Ulex europaeus, and Rubus ulmifolius was evaluated using a fire simulation tool in three areas with contrasting physio-climatic conditions. Our simulation results demonstrated the effectiveness of shrub management on three critical wildfire indicators. Namely, significant decreases were observed in fireline intensity (kW/m) 58–75%, flame length (m) 0–40%, and heat per unit area (kW/m2) 86%. Furthermore, a biomass quality index (BQI) was developed based on the physicochemical parameters of the three shrubs assessed. Based on this BQI, T. monspessulana was selected as the most promising shrub biomass and was consequently used in a pilot shrub-pinewood blending to produce pellets. A blending of 20:80%m/m exhibited properties close to the ISO standard. Our results show that the management of invasive shrubs has the potential to minimize the virulence of wildfires, while the physicochemical characteristics and availability of one of the shrubs analyzed (T. monspessulana) make it a viable alternative biomass source for pellet production in the region.

This study investigated pellets produced using shrub biomass blended with pine sawdust to improve their physical and combustion properties by incorporating additives. First, the properties of pellets produced at different temperatures were analyzed. Pellets produced using pine sawdust blended with Teline monspessulana and Ulex europaeus biomasses (80/20 %m/m) exhibited good properties when prepared at 50–60 ◦C, whereas pellets produced using Rubus ulmifolius exhibited better characteristics at lower temperatures. The results showed that further studies on the physical properties and operational conditions of biomass from Ulex europaeus and Rubus ulmifolius are required. Furthermore, pellets blended with Teline monspessulana were evaluated using starch and lignin as binders, which exhibited all the physical properties of ISO 17225–6 when 1 wt% lignin was added owing to the stronger bonding induced by the additive. Because the fuel indices indicated a high corrosion risk, the additive CaO was used to improve the combustion performance of pellets blended with Teline monspessulana biomass and binders. The content of particulate matter smaller than 2.5 and 10 μm decreased by approximately 50%, and the crystallinity of the bottom ash, which usually contains undesirable elements, was improved by adding 1 wt% CaO, which raised the melting temperature of the ash.