A review on the requirements for environmentally friendly insulating oils used in high-voltage equipment under the...

The advancements in electricity production and distribution, as well as the growing consumption of electrical energy, have made electrical equipment a vital part of the technological infrastructure. On the other hand, the necessity for environmentally safe and sustainable solutions is another requirement for electrical transformers, the same as for every technology and equipment nowadays. In this aspect, the main challenges in electrical transformers are the reduction in power losses, the use of construction materials with minimum environmental impact, and the elongation of their service life. All three challenges are related to the insulating oils that are used in the transformers which are exclusively mineral based and are products of crude oil. Mineral oils can almost be fully recyclable and can be regenerated with satisfactory results. However, they are not biodegradable, they are flammable, and they may present toxic properties for both humans and the environment. Bio-based lubricants are fully recyclable and can be regenerated, they have none of the hazardous properties of mineral oils, and are fully biodegradable. Furthermore, they are considered a sustainable solution, since they are not fossil-based but products of cultivation and the supplies can be considered indefinite. This paper tries to present an assessment of the environmental impact of vegetable-based insulating oils for electrical transformers, in the wider view of sustainability global efforts, considering additional environmental impact compared with the already used in related works. The assessment is executed for the whole life cycle of two product groups of transformers, as determined by the EU Eco Design Directive 2009/125/EC and the EU Regulation 548/2014 on eco design of requirements on transformers.