Life Cycle Assessment (LCA) of Natural and Petroleum-Based Glycols

1,3-Butylene glycol (1,3-BG), such as glycols, plays an important role in the development of cream, sunscreen, shampoo, shower gel and many other personal care product formulations. As concerns about petroleum-based raw materials continue to grow, consumers have begun to consider the lifecycle impact of the materials used in their products, in addition to their natural and sustainability characteristics, taking into account raw material sources and production processes. To address these concerns, Genomatica has conducted a study comparing their developed naturally sourced, bio-based 1,3-BG (Brontide™) and petroleum-based alternative market products systematically under lifecycle assessment (LCA). As a result, when petroleum-based alternative 1,3-BG product production was compared with the bio-based 1,3-BG production process, it was observed that the global warming potential was 103% higher and energy demand from non-renewable sources was 85% higher. The results of this study will serve as a guide for personal care formulators in selecting raw materials with lower environmental impact.

Traditional 1,3-Butylene Glycol Production and a Natural Alternative

1,3-BG is a four-carbon organic raw material used in personal care and cosmetic products. In addition to being a humectant, solvent and softener for skin and hair care, it is used as a solvent for high-purity plant extracts. In general, cosmetic-grade 1,3-BG production is carried out through a production process that includes condensation, hydrogenation and removal of impurities through polishing and distillation. Unlike factors included in lifecycle assessment, many users of 1,3-BG have concerns about the production process involving acetaldehyde, which is a mutagen and Group 1 carcinogen. Genomatica has developed an alternative production method called GENO BG™ for cosmetic-grade 1,3-BG production. The result of this process is Brontide, a naturally sourced, sustainably produced butylene glycol. The production process uses an engineered E. coli strain to produce crude 1,3-BG and is carried out through fermentation of dextrose derived from plants; high-purity Brontide is then produced with additional distillation and purification stages. Lifecycle assessment is a well-established method for evaluating the environmental impacts of each step in a product's production, from raw material extraction to disposal. Assessing these two different production processes will help personal care manufacturers determine how their products affect the environment.

Methods Used in Lifecycle Assessment of Brontide and Petroleum-Based 1,3-BG

Lifecycle assessment for these production processes was conducted using standard methods and procedures specified by the conditions and guidelines in ISO 14044. Activities involved in the production processes include raw material extraction, processing, chemical production, final product production and cover topics such as energy, process chemicals and waste management. A detailed inventory of inputs and outputs for each of these steps was modeled based on representative data available for current technologies. The lifecycle assessment model was constructed using the GaBi 8 software system for lifecycle engineering and was reviewed by three independent experts. [Arpad Horvath, PhD (Independent Consultant); Susan Jenkins, PhD (Innovative Genomics Institute, University of California, Berkeley); and Julie Sinistore, PhD (WSP USA Inc.)].

Table 1. Impact categories according to Geno BG production process.

Complications of Corn Raw Material Cultivation

In contrast, the bio-based Brontide production process was observed to have greater impact than the petroleum-based 1,3-BG production route when other environmental measures were analyzed. The relative impact of Brontide production on AP, EP, SFP and BWC measures stems primarily from plant-based raw materials, particularly emissions from corn cultivation and indirect activities. The impact of Brontide production on these environmental metrics will vary by geography and careful site selection can help minimize the results reported for these secondary outcomes. Fertilizer used for corn cultivation is rich in organic nitrogen (NOX), sulfur dioxide (SO₂) and phosphate (PO₄^3-) and its runoff into freshwater rivers and streams can have significant environmental impact on soil acidification and eutrophication in agricultural areas. In fact, soil acidification tends to be a concern only in a very narrow cluster of corn-producing regions in Europe and the United States where the soil pH is already very low. The greater impact of bio-based routes on EP due to fertilizer use in corn cultivation; SFP cultivation due to emissions from tractors used for corn; BWC due to corn irrigation and evaporation loss are accepted in relation to this study although they are an estimate based on current input and output values. In fact, the degree of environmental impact can be minimized depending on various factors in the production process.

Ozone Depletion Potential

Finally, the ODP results of the bio-based process significantly exceed those of the petroleum-based product. However, these results are six orders of magnitude lower than the other impact categories analyzed and are therefore considered insignificant when the absolute values of each route are normalized to TRACI 2.1 US person equivalents. For this reason, although ozone layer thinning has significant negative effects on animal and plant life, the differences between routes in ODP results are not considered in relation to the overall conclusions regarding the environmental superiority of one route compared to another.

Facts on Petroleum-Based and Bio-Based Methods of 1,3-BG Production

The petroleum-based 1,3-BG production route significantly exceeds bio-based Brontide production in both GWP100 and PENRE measures. The increase in both of these important impact categories is of major environmental and social significance because it may have irreversible impacts on human life, the environment and conservation. While the bio-based production route was found to have greater impact on other measures studied, both AP and ODP were accepted as irrelevant. As the benefits of the bio-based production route for 1,3-BG began to be understood, lower SFP, EP and BWC emissions could also be achieved through optimization of specific steps in the production process. When comparing both methods, the bio-based 1,3-BG production route was shown to create less environmental impact than the conventional petroleum-based process. Genomatica hopes that this lifecycle assessment will help formulators select materials with reduced environmental impacts for personal care and cosmetic formulations and help product manufacturers work toward a more sustainable future. By: Kyle Huston Product Manager Specialty Chemicals Genomatica         Compiled and Translated by: Özge Yüksel Özel Technical Business Development Manager Personal Care Azelis TR      

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