Dra. Azócar-Ulloa, Laura

This study presents a systematic cradle-to-grave assessment of greenhouse gas (GHG) emissions from four biomass utilization pathways: combustion, pyrolysis, gasification, and anaerobic digestion. Emission factors (EF) were developed through comprehensive literature synthesis of 149 datasets from 29 peer-reviewed publications, encompassing cultivation, transport, pretreatment, conversion, and construction emissions, as well as carbon sequestration and energy offset benefits. The studies were compared using an emission factor as approximate value. Potential GHG sinks through the use of biogenic residues were calculated based on the emission factor and residue potential databases. Results indicate that previously unused biogenic residues using the utilization pathways pyrolysis have significant GHG reduction potential (from 11.0 million to 19.1 million t CO2e). Quantitative analysis reveals woody biomass residues in pyrolysis applications achieved the most favorable GHG performance (−0.87 ± 0.44 t CO2e/t feedstock), followed by combustion (−0.78 ± 0.28 t CO2e/t feedstock). Herbaceous biomass residues demonstrated similar trends with pyrolysis (−0.67 ± 0.37 t CO2e/t) outperforming combustion (−0.60 ± 0.20 t CO2e/t). From 2045, avoidable GHG emissions from urea and lime fertilization in Germany (2023: 13.7 million t CO2e) could be fully compensated on average by focusing on the technically useable potential of biogenic woody and herbaceous biomass residues.

Nowadays, leaves, bark, and branches are generated from the tree-pruning process in urban places, where their management is a problem because of the necessity of disposal. These wastes are lignocellulosic biomasses with poor properties for use in biofuel production, but with interesting projections for building block products such as phenol compounds. Therefore, extensive biomass characterization of urban pruning from Liquidambar styraciflua L. was developed to evaluate its composition as a tool for phenol production through thermal processing, in which solvent extraction is a complementary tool for selectivity improvement. The results showed high lignin content in bark and leaves at 45 and 28 %, respectively, compared with that in branches (14 %). Additionally, high extractives in leaves (14 %) could be an additional source of phenols. The lignin units were analyzed by Raman dispersion, revealing p–hydroxyphenyl (H) units in the bark, guaiacyl (G) units in the bark and leaves, and syringyl (S) units only in the branches. Furthermore, the micropyrolysis coupled with gas chromatography/mass spectrometry assay realized at 600 ◦C showed high presence of phenolic compounds in the three biomass investigated, where a high phenol concentration was identified in leaves, probably due to the S unit degradation during pyrolysis. With these results, an assay for bio-oil production was performed in a low-temperature pyrolysis reactor using leaves as feedstock, reaching a low bio-oil yield with high water content favored for the high inorganic content of leaves (13 %). The produced bio-oil was used for liquid–liquid extraction evaluation, where 1-octanol and methyl isobutyl ketone were identified as interesting solvents for catechol and phenol extraction, respectively. This article presents the challenge of characterizing each part of urban trees, which could be a tool to promote the use of urban pruning by studying the thermal degradation mechanism to implement processes for high-value products, such as phenols produced from L. styraciflua L.