Evaluation of sugar feedstocks for bio‐based chemicals: A consequential, regionalized life cycle assessment

Abstract

Fermentable sugars are an attractive feedstock for the production of bio-based chemicals. However, little is known about the environmental performance of sugar feedstocks when demand for sugars increases, and when local conditions and sensitivities of receiving ecosystems are taken into account. Production of monosaccharides from various first-and second-generation feedstocks (sugar beet, sugar cane, wheat, maize, wood, residual woodchips, and sawdust) in different geographic locations was assessed and compared as feedstock for monoethylene glycol (MEG) using consequential, regionalized life cycle assessment. Sugar cane grown in Thailand performed best in all three areas of protection, that is, for life cycle impacts on human health, ecosystem quality, and resources (respectively, equal to −7.6 × 10 −5 disability-adjusted life years, −1.2 × 10 −8 species-years and −0.046 US dollars per amount of feedstock needed to produce 1 kg of MEG).This was mainly due to benefits from by-products-incineration of sugar cane bagasse generating electricity and use of sugar cane molasses for the production of bioethanol. The wood-based feedstocks and maize performed worse than sugar cane and sugar beet, but their evaluation did not consider that sugar extraction technology from lignocellulose is immature, while identification of marginal suppliers of the marginal crop is particularly uncertain for maize. Wheat grown in Russia performed the worst mainly due to low agricultural yields (with impacts equal to 8.9 × 10 −5 disability-adjusted life years, 6.9 × 10 −7 species-years, and 1.8 US dollars per amount of feedstock required to produce 1 kg of bio-based MEG). Our results suggest that selection of sugar feedstocks for bio-based chemicals should focus on (i) the intended use of by-products and functions they replace and (ii) consideration of geographic differences in parameters that influence life cycle inventories, while spatial differentiation in the life cycle impact assessment was less influential.

Microbial Enzyme Systems in the Production of Second Generation Bioethanol

“…The first generation, which is produced using food crops, accounts for the majority of the bioethanol currently produced. Examples include the United States, which makes ethanol from corn, Brazil, which makes ethanol from sugarcane, and Europe, which makes ethanol from wheat and barley [11,12]. Recent concerns about the production of firstgeneration biofuel brought about by the conflict between food and fuel have prompted field experts to look into alternate paths for biofuel production [13].…”

Comprehensive life cycle assessment of the corn wet milling industry in the United States

“…Because the primary focus for corn products has so far been on the fuel pathway, most studies focus on dry milling and/or stop at fermentable sugars (see, e.g., Ortiz-Reyes and Anex, 2020) or leave the refining of starch to sweeteners largely opaque or aggregated (e.g., Wang et al, 2007, and the evolution of those pathways, including Xu et al, 2022). Of those studies that do consider fructose or high fructose sweeteners, the vast majority use library processes (see, e.g., Fabbri et al, 2023;Moreno et al, 2020, and others) which typically reflect older data, not current information.…”

“…Due to the limitations in available inventories and environmental impacts for corn wet milling and refining, the determination of environmental impacts for products in which HFCS55 is an input have needed to rely upon older data, less certain models, and/or been unable to reflect current, industry average HFCS55 for use in their supply chain. As demand for carbon accounting of products expands across many sectors of economies throughout the world, a robust life cycle inventory and assessment of corn sweeteners, particularly HFCS, is needed to support those studies as well as the development of other biobased products (Fabbri et al, 2023;Flugge et al, 2017;Lee et al, 2021;Moreno et al, 2020).…”