Abstract
Biomass is an important component of the Brazilian energy matrix, with a potential contribution of co-products from thinned forests. The aim of this work was to evaluate the energy balance and CO2 potential emission in mechanized biomass harvesting operations in Pinus taeda stands at 9 and 10 years-old and under thinning, searching to support the use of co-product biomass from thinning as a renewable energy source. Thinning was carried out through cut-to-length harvesting method, in which large logs for sawmill and small logs for energy were produced. In addition, tops, needles, barks, and branches were considered as co-products. The balance between consumed energy and emitted CO2 by machines for thinning in relationship to the energy and CO2 in thinned biomass was estimated. Thus, dry matter, energy potential, and CO2 potential emission were evaluated and compared considering thinning stand ages as treatments. Mechanized thinning consumes a large energy and produces CO2, however, the energy consumed by machines is lower than 1% of the estimated energy potential in thinned biomass, while the CO2 emission is lower than 0.5% of the biomass. Therefore, the use of co-product biomass of thinning is an important way to mitigate greenhouse gas emission.
Highlights
Biomass is an important component of the Brazilian energy matrix, which represents 25.4% of the total domestic supply, consisting of sugarcane biomass, firewood, and charcoal (EPE 2018)
The aim of this work was to evaluate the energy balance and CO2 potential emission in mechanized biomass harvesting operations in Pinus taeda L. stands under the first thinning, searching to support the use of co-product biomass from thinning as a renewable energy source
Forwarder machine shows an effective time of 2.5 hours per hectare, with a mean fuel consumption of 27.8 L, energy potential equal to 1.1 GJ ha-1 and CO2 emission of 0.07 Mg ha-1 (Table II)
Summary
Biomass is an important component of the Brazilian energy matrix, which represents 25.4% of the total domestic supply, consisting of sugarcane biomass, firewood, and charcoal (EPE 2018). Wood harvesting can be an important source of co-products in stands under thinning, such as Agrarian Sciences. In pine stands, thinning is applied along the forest rotation period, mainly in ages before the growth and yield biomass stagnation (Del Río et al 2017, Rodrigues et al 2018). In Brazil, the use of co-product biomass for energy is limited to the forest final cutting through full-tree harvesting method and at short distances between field and consumer unit. On the other hand, mechanized thinning is predominantly carried out through cut-to-length harvesting, in which most co-products remain on the forest ground and due to the difficulty of removal and processing. Brazilian forestry companies usually choose to leave co-product biomass on the field, aiming to contribute for nutrient cycling and reduce soil compaction (Szymczak et al 2014)
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