Life cycle assessment of high oleic natural ester‐based insulating oil for carbon footprint reduction in sustainable transformer

Abstract

Improving energy efficiency and reducing greenhouse gas (GHG) emissions are essential for the transition to low‐carbon power systems and sustainable grid infrastructure. Mineral oil‐based insulating oil has a higher lifecycle carbon footprint due to petroleum extraction and refining. Natural ester fluids, derived from plant sources, offer lower CO ₂ emissions, are biodegradable, and are less toxic. They also improve fire safety with a higher flash point. This study presents a life cycle assessment (LCA) of High Oleic Natural Ester (HONE)‐based insulating oil as a sustainable alternative for transformer applications. The thermal performance of HONE was evaluated through accelerated thermal aging experiments using both standard Kraft paper and Thermally Upgraded Kraft (TUK) paper insulation systems, benchmarked against mineral oil and conventional natural ester. Results demonstrate that HONE significantly slows cellulose degradation, enabling higher thermal class operation and increased loading without additional loss of life. HONE‐filled transformers can operate at hotspot temperatures up to 137°C, allowing up to 27% higher loading than mineral oil–filled units. This enhanced thermal capacity enables the engineering design of smaller, more compact transformers operating at higher load ratings—a direct pathway to material and resource conservation. From an LCA perspective, the transition to HONE‐based insulating oil in a sustainably designed transformer is estimated to reduce CO ₂ emissions by approximately 27% compared to a peak‐rated transformer using mineral oil over a 30 years’ service life. These findings demonstrate a practical, industrially viable engineering solution at the intersection of sustainable energy infrastructure and chemical engineering.