Environmental assessment of xylitol production routes for thermal energy storage applications: A critical review

Studies show xylitol as a promising material for thermal energy storage applications. This work aims to critically review, collect, and produce useful data about the life cycle impacts of xylitol's production. One of the practical implications of this work is that it allows the identification of inputs that require attention in decision-making according to various environmental impact indicators. The methodology included a review of the production pathways and market, a systematic review, and a life cycle assessment comparing the production routes. The systematic review showed great variability in the global warming potential regardless of the production pathway, biotechnological or chemical, associated with life cycle assessment assumptions, making a fair comparison between both production processes unfeasible. Thus, a life cycle assessment was conducted with the same assumptions for farming, transportation, and manufacturing stages, finalizing with a local sensitivity analysis to identify the critical inputs. Manufacturing in the chemical process contributes to more than 75 % of the environmental impacts compared to farming and transportation, except for water consumption potential (m3). A breakdown of the manufacturing flows shows that energy usage for the biotechnological process, and energy plus nickel catalyst for the chemical process are the key contributors, confirmed by the local sensitivity analysis. Overall, the biotechnological process showed a global warming potential of 2.2 kg CO2 eq per kg of xylitol. In comparison, the chemical process had a value of 8.8 kg CO2 eq per kg of xylitol, and the same behavior is observed on most of the impact category indicators.