Harmonized Life-Cycle Inventories of Nanocellulose and Its Application in Composites

Cellulose nanocrystals (CNC) and nanofibers (CNF) have been broadly studied as renewable nanomaterials for various applications, including additives in cement and plastics composites. Herein, life cycle inventories for 18 previously examined processes are harmonized, and the impacts of CNC and CNF production are compared with a particular focus on GHG emissions. Findings show wide variations in GHG emissions between process designs, from 1.8–1100 kg CO2-eq/kg nanocellulose. Mechanical and enzymatic processes are identified as the lowest GHG emission methods to produce CNCs and CNFs. For most processes, energy consumption and chemical use are the primary sources of emissions. However, on a mass basis, for all examined production methods and impact categories (except CO emissions), CNC and CNF production emissions are higher than Portland cement and, in most cases, are higher than polylactic acid. This work highlights the need to carefully consider process design to prevent potential high emissions from CNCs and CNF production despite their renewable feedstock, and results show the magnitude of conventional material that must be offset through improved performance for these materials to be environmentally favorable.

*Waste to treatment is omitted from the analyses reported in text due to inconsistent reporting of waste flows in harmonized studies.
Table S25.GHG emissions (in kg CO 2 -eq / kg nanocellulose) for the 115 combinations of feedstock and process modeled.

Table S2 .
Inventory for 1kg of CNC -Acid hydrolysis -Forest Products Laboratory -kraft pulp (Gu et al.1 ) *Waste to treatment is omitted from the analyses reported in text due to inconsistent reporting of waste flows in harmonized studies.

Table S5 .
Inventory for 1kg of CNC -Chemical acid hydrolysis -kraft pulp (de Figueirêdo et al.3 ) *Waste to treatment is omitted from the analyses reported in text due to inconsistent reporting of waste flows in harmonized studies.

Table S9 .
Inventory for 1kg of CNC -Lignin-containing -Deep eutectic solvent (DES) pretreatment, minimum -kraft pulp (Zargar et al.4 ) *Waste to treatment is omitted from the analyses reported in text due to inconsistent reporting of waste flows in harmonized studies.

Table S13 .
Inventory for 1kg of CNF -Enzymatic treatments and homogenisation -kraft pulp (Stampino et al.6 ) *Waste to treatment is omitted from the analyses reported in text due to inconsistent reporting of waste flows in harmonized studies.

Table S14 .
Inventory for 1kg of CNF -Etherification and homogenisation -kraft pulp (Li et al.7 ) *Waste to treatment is omitted from the analyses reported in text due to inconsistent reporting of waste flows in harmonized studies.

Table S15 .
Inventory for 1kg of CNF -Etherification and sonification -kraft pulp (Li et al.7 ) *Waste to treatment is omitted from the analyses reported in text due to inconsistent reporting of waste flows in harmonized studies.

Table S21 .
Inventory for 1kg of CNF -TEMPO-oxidation and homogenisation -kraft pulp (Stampino et al.6 ) *Waste to treatment is omitted from the analyses reported in text due to inconsistent reporting of waste flows in harmonized studies.

Table S22 .
Inventory for 1kg of CNF -TEMPO-oxidation and homogenisation -kraft pulp (Li et al.7 ) *Waste to treatment is omitted from the analyses reported in text due to inconsistent reporting of waste flows in harmonized studies.

Table S23 .
Inventory for 1kg of CNF -TEMPO-oxidation and sonication -kraft pulp (Li et al.7 ) *Waste to treatment is omitted from the analyses reported in text due to inconsistent reporting of waste flows in harmonized studies.

Table S26 .
CED (in MJ / kg nanocellulose) for the 115 combinations of feedstock and process modeled.

Table S27 .
VOC emissions (in kg VOC / kg nanocellulose) for the 115 combinations of feedstock and process modeled.

Table S28 .
SO x emissions (in kg SO 2 -eq / kg nanocellulose) for the 115 combinations of feedstock and process modeled.

Table S29 .
NO x emissions (in kg NO 2 -eq / kg nanocellulose) for the 115 combinations of feedstock and process modeled.

Table S30 .
PM 2.5 emissions (in kg PM 2.5 -eq / kg nanocellulose) for the 115 combinations of feedstock and process modeled.

Table S31 .
CO emissions (in kg CO / kg nanocellulose) for the 115 combinations of feedstock and process modeled.

Table S32 .
Pb emissions (in mg Pb / kg nanocellulose) for the 115 combinations of feedstock and process modeled.