24th International Colloquium Tribology - January 2024 243 Sustainability Assessment of Polyol Esters - A Comparative LCA Analysis of a Bio-Based vs. Fossil-Based Product Verena Koch 1 , Denise Haas 2 1 Peter Greven GmbH & Co. KG, Bad Muenstereifel, Germany 2 Peter Greven GmbH & Co. KG, Bad Muenstereifel, Germany 1. Introduction In the urgent context of climate change a critical question emerges: Can materials and products derived from renewable carbon reduce greenhouse gas emissions when compared to the established fossil-based counterparts? Answering such a question demands in-depth assessment and the method of choice for this kind of evaluations is a Life Cycle Assessment (LCA). We present a peer-reviewed LCA study - representing the highest possible scientific standard - that examines the carbon footprint of a product mainly made from renewable carbon vs. a fossil-based product. This kind of examination is significant as defossilisation is the right strategy to eliminate additional influx of fossil carbon into our carbon cycles and the atmosphere - but at the same time we need to ensure that the alternatives really reduce greenhouse gas emissions. The principle advantage of renewable carbon feedstock is that it originates from atmo-, bioand technosphere and therefore does not bring additional fossil carbon from the land into the carbon cycle above the ground. Instead, these feedstocks help to build and realise a truly circular economy and circular carbon loops [1]. 1.1 Life Cycle Assessment (LCA) LCAs are globally recognised as the gold standard for assessing the environmental impacts of products and services. LCA is an internationally standardized method laid out in ISO 14040: 2006 and ISO 14044: 2006. They analyse every stage of a product’s life, providing a comprehensive understanding of their environmental impacts. Peer-reviewed LCAs are particularly valuable as they undergo rigorous expert scrutiny, ensuring the reliability of their findings and enabling reliable public assertions in terms of environmental preference. The LCA procedure [2] 1.2 Carbon Footprint of Bio-based Materials It is essential to recognize that the carbon footprint of biobased materials is not automatically close to zero for two primary reasons: Fossil energy in the value chain: The growth or provision of raw materials, transportation as well as product manufacturing stages involve energy consumption and a substantial amount of grid mix energy is still derived from fossil sources. In particular the agricultural sector, as a key provider of biomass, is still strongly reliant on fossil resources e.g. for fertilisers, pesticides or simply the diesel needed to run machinery. This reliance on fossil feedstock within the value chain significantly impacts the overall carbon footprint. Land Use Change: Land use change refers to the alteration or conversion of a particular area of land from one land use type to another. It involves the transformation of land for various purposes such as agriculture, urban development, forestry, mining or infrastructure projects. Land use change has significant impacts on the environment, biodiversity, climate and socio-economic aspects. Climate change impact for biobased materials is mostly linked to the deforestation to get arable land. Understanding and managing land use change is crucial for sustainable development and environmental conservation. Effective land use policies, land zoning and conservation efforts are necessary to ensure responsible land use change and minimize negative impacts on ecosystems and communities. Sustainably certified production can significantly lower greenhouse gas emissions [3]. 2. Current Study This case study provides you with key LCA insights of polyol esters and how a bio-based product can help to mitigate climate change by reducing greenhouse gases [4]. The study was carried out following the LCA standards laid out in ISO 14040 [2] and ISO 14044 [5]. External critical review as described in the standards has been performed by a review panel consisting of three independent reviewers. This LCA covers all relevant life cycle stages from cradle-to-gate, which means from the supply of raw materials to the manufacturing of the products. For the impact assessment, the sixteen potential impacts from the EF 3.0 method were investigated. These include climate change, the depletion of resources and impact on humans and ecosystems. 244 24th International Colloquium Tribology - January 2024 Sustainability Assessment of Polyol Esters - A Comparative LCA Analysis of a Bio-Based vs. Fossil-Based Product Impact categories Impact category Indicator Climate change Radiative forcing as Global Warming Potential with a time horizon of 100 years (GWP100) Resource use, fossils Abiotic resource depletion ultimate reserves Resource use, minerals and metals Abiotic resource depletion - fossil fuels Particulate matter Disease incidence due to exposure to PM2.5 Ozone depletion Ozone Depletion Potential Photochemical ozone formation Tropospheric ozone concentration increase Ionising radiation Human exposure efficiency relative to U235 Acidification Accumulated Exceedance Eutrophication, freshwater Fraction of nutrients reaching freshwater end compartment (P) Eutrophication, marine Fraction of nutrients reaching marine end compartment (N) Eutrophication, terrestrial Accumulated Exceedance Land use Soil quality index Water use User deprivation potential Human toxicity, non-cancer Comparative Toxic Unit for humans Human toxicity, cancer Comparative Toxic Unit for humans Ecotoxicity, freshwater Comparative Toxic Unit for ecosystems A comprehensive sensitivity analysis on different explorative scenarios and allocation scenarios was carried out in order to determine how value and methodological choices related to this issue affect the results and conclusions of this LCA. 2.1 Assessed Products LIGALUB 19 TMP is a polyol ester with a bio-based carbon content of 81% (measurement based on ASTM D 6866: 2008) used for lubricant applications and produced by Peter Greven, a leading manufacturer of oleochemical products based on renewable raw materials. It is produced by the esterification of a fatty acid made from palm kernel oil and an alcohol, trimethylolpropane (TMP). Conventional lubricant esters based on isotridecanol and adipic acid, such as diisotridecyladipate (DITA) can be considered as direct counterpart for LIGALUB 19 TMP. Both reactants for the production of DITA are commonly derived from petrochemical feedstocks. DITA was used as fossil-based reference system because it is a lubricant ester with similar product properties compared to LIGALUB 19 TMP. Both are equally suitable as lubricant component e.g. for engines, gearboxes and hydraulic oils. The results of an investigation of the physical properties support the selection of DITA as suitable reference [4]. 2.2 Results The environmental impacts were found to be lower for LIGA- LUB 19 TMP in comparison to DITA in the following evaluated categories: climate change, use of fossil resources and photochemical ozone formation. In summary, the bio-based alternative to DITA can help to reduce carbon emissions and support the defossilisation. References [1] Plum, M. et al. 2023: Case Studies Based on Peer-reviewed Life Cycle Assessments - Carbon Footprints of Different Renewable Carbon-based Chemicals and Materials [2] ISO 2006: Environmental management - Life cycle assessment - Principles and framework (ISO 14040: 2006). [3] Schmidt, J. and De Rosa, M. 2020: Certified palm oil reduces greenhouse gas emissions compared to non-certified. Journal of Cleaner Production, Vol. 277 10.1016/ j.jclepro.2020.124045 [4] nova-Institut für politische und ökologische Innovation GmbH 2023: Life Cycle Assessment -Ligalub 19 TMP [5] ISO 2006: Environmental management - Life cycle assessment - Requirements and guidelines (ISO 14044: 2006); German and English version EN ISO 14044: 2006.