The role of ester fluids in Europe’s ageing grid infrastructure

European distribution grids will need investments of €375-425 billion until 2030, concludes a study [1] by Eurelectric, Monitor Deloitte and smart grid organisation E.DSO. Based...

byTim Martin


European distribution grids will need investments of €375-425 billion until 2030, concludes a study [1] by Eurelectric, Monitor Deloitte and smart grid organisation E.DSO. Based on detailed empirical data from ten European countries, Connecting the Dots: distribution grid investment to power the energy transition suggests investments in distribution grids will need to increase by 50-70 %, from 2020 to 2030, compared with the previous decade. That is equivalent to €34-39 billiona year.

The single biggest investment driver is modernisation of ageing infrastructure. The study found that a third of the EU’s grids are already over 40 years old, a figure increasing to fifty percent by 2030.

Transformers, designed to step power up or down, are a critical component of any power grid. Upgrading or replacing these assets constitutes a key aspect of any grid modernisation investment programme. Liquid filled distribution transformers are used in medium voltage (MV) and high voltage (HV) applications – historically using mineral oil as the dielectric insulating and heating media fluid. Liquid filled transformers are robust assets, with low load losses and long service lifetimes of around 35 years [2], making them a popular option for outdoor as well as indoor environments, compared with dry type, or air cooled, transformers, which require more maintenance.

However, in our experience, there is a growing awareness of two critical flaws in the use of mineral oil as an insulating

fluid – its potential flammability and its poor biodegradation characteristics in case of a major failure.

For any distribution network operator (DNO), or utility, transformer fleet upgrades can potentially be a costly undertaking, especially from a capital expenditure (Capex) perspective. Utilities will want to consider solutions that can safely extend asset life and optimise loading performance. Retrofilling transformers with natural or synthetic ester fluid to replace mineral oil is a perfect example of such a solution.

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