A systematic review on promising development of cost-effective, biodegradable, and environment friendly vegetable based nanofluids as a future resource for green transformer insulation oil

The contribution of this article is to update the reader on the latest developments of transformer insulating oils in ensuring the reliability of power systems. Commencing with the prevalent use of mineral oil (MO), our exploration extends to alternative solutions, including esters. The scrutiny of esters involves a particular emphasis on natural variants highlighting their potential as eco-friendly substitutes for conventional insulating oils. A significant aspect of this work entails the incorporation of different nanoparticles (NPs) into vegetable insulating oils, forming nanofluids, which emerge as a promising avenue for enhancing insulating properties. The paper systematically categorizes nanoparticles based on conductivity and thoroughly examines nanofluid synthesis methods. Stability assessment techniques, encompassing sedimentation capturing, zeta potential analysis, and spectral analysis, are discussed alongside strategies for stability enhancement, including surfactant addition, surface modification, ultrasonic agitation, and pH control. Environmental considerations, covering biodegradability, recyclability, and fire protection, are scrutinized for both mineral and vegetable oils.