The first Eco design High Voltage & Medium Voltage low loss transformer is insulated with natural ester, a totally biodegradable vegetable oil, and generates reduced CO2 emissions. It is the result of the joint work of Enel Grids and Hitachi Energy, who have achieved a key result in terms of both environmental sustainability and safety. This is a significant engineering achievement in keeping with Enel's Net Zero strategy, which provides for a significant evolution of electricity distribution infrastructure towards the goal of carbon-free networks.The joint work of the Enel Grids and Hitachi Energy teams has led to the approval of a transformer with a nominal power rating of 40 MVA, an innovative technological solution with the aim of gradually reducing the infrastructure's indirect emissions to zero. The use of natural ester as an insulator instead of traditional mineral oil results in a significantly reduced carbon footprint, from production to disposal. This natural dielectric liquid also has much better fire resistance qualities than mineral oil, and therefore also offers important advantages from the point of view of fire prevention. The development and implementation of the project took place at the Hitachi Energy plant in Monselice, in the province of Padua, Italy, while the actual commissioning of the transformer will take place at the Primary Substation in Caltagirone, in the province of Catania. This is a cutting-edge solution that, among other things, is another innovation first for the distribution networks.The transformer is designed to be fully interchangeable with conventional transformers, and therefore will not require any on-site adaptation. The transformer set up at the Monselice plant is just the first in a series of similar initiatives by Enel Grids: another 20 natural ester insulated transformers have already been commissioned, with the aim of installing them in Europe and South America. The transition of large power transformers takes longer and is therefore taking place more gradually, but for distribution network transformers, Enel Grids has already adopted a global strategy to supply 50% of them in natural gas.