Residual pyrolysis biochar as additive to enhance wood pellets quality

Woody biomass pellets' demand for primary energy production is increasing. To guarantee sustainable and cost-efficient pellet production the diversification of biomass feedstock is mandatory. In this work it is proposed to re-use the solid biochar obtained from pyrolysis of eucalyptus (PEc) at...

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Bibliographic Details
Published in:Renewable energy 2021-12, Vol.180, p.850-859
Main Authors: García, R., Gil, M.V., Fanjul, A., González, A., Majada, J., Rubiera, F., Pevida, C.
Format: Article
Language:English
Subjects:
Biochar
Biomass
Energy density
Pelletization
Valorization
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Summary:Woody biomass pellets' demand for primary energy production is increasing. To guarantee sustainable and cost-efficient pellet production the diversification of biomass feedstock is mandatory. In this work it is proposed to re-use the solid biochar obtained from pyrolysis of eucalyptus (PEc) at 700 °C as an additive to produce enhanced pine sawdust (PIN) pellets. The process required the addition of glycerol as a lubricant in a percentage of 1 and 2 wt% per 5 and 10 wt% of pyrolyzed eucalyptus in the blend, respectively. Small additions of PEc enhanced PIN pellets’ grindability and water-resistance, providing products with remarkable values of durability (up to 99%), net calorific value (up to 20 MJ/kg), energy density (up to 13.3 GJ/m3), and particle density (up to 1.24 g/cm3). N, S, chlorine, and heavy metals contents were also analyzed. The proposed pellets fulfill the A1/A2 and the I1/I2 quality classes for domestic and industrial wood pellets, respectively. A preliminary economic evaluation indicated that pellets made up from a mixture of 90% PIN and 10% PEc are competitive compared to raw PIN pellets, with expected savings in the costs of production, energy, transport, and construction of a storage site of 4, 13, 10 and 7%, respectively. •Valorization of a solid waste, eucalyptus biochar (PEc), is proposed.•Pine sawdust (PIN) pellets with PEc and glycerol as additives are formulated.•PEc addition below 10 wt% enhances PIN pellets' heating value and energy density.•PEc addition below 10 wt% enhances PIN pellets' grindability and water-resistance.•PEc-PIN pellets are economically competitive when compared to PIN.
ISSN:0960-1481
1879-0682
DOI:10.1016/j.renene.2021.08.113