Synthetic esters have been used as insulating fluids in transformers for many years. But what happens to these high-quality fluids once they have been in service for a long time or their properties no longer meet the required specifications? Electrical Oil Services has specialised in the treatment and recycling of insulating oils for decades. With EOS® RePure, the company is now applying this approach to synthetic esters: Electrical Oil Services recycles used synthetic esters and uses them to produce a new ester fluid for reuse as an insulating fluid. It is the first 100% recycled ester fluid.
What happens to synthetic esters after years in service?
Like other insulating fluids, synthetic esters change over the course of their service life. Ageing processes and contaminants affect their properties. When an ester is removed from a transformer, the question therefore arises as to how this valuable resource can continue to be used.
Through recycling, used synthetic ester can serve as the raw material for a new ester fluid.
Elemental sulphur: a challenge for synthetic esters
One topic currently receiving increased attention within the transformer industry is elemental sulphur (S8). Recent research shows that elemental sulphur can also occur in synthetic esters and, under certain conditions, contribute to the corrosion of silver-plated components.
Research and standardisation activities are therefore focusing on suitable test methods, risk assessment and possible mitigation measures. Existing standards and test methods are also being further developed.
EOS® RePure: turning used ester into a new insulating fluid
The challenges associated with the further use of used synthetic esters prompted Electrical Oil Services to develop a new solution: EOS® RePure. Electrical Oil Services collects and recycles used synthetic esters. This raw material is used to produce EOS® RePure – the first 100% recycled ester fluid.
This gives used ester a new purpose: it becomes the raw material for a new product that can be used in all applications in which virgin synthetic ester fluids are used.
The removal of elemental sulphur also plays an important role in its development. The process is based on IP-protected know-how provided by the Nikola Tesla Institute of Electrical Engineering. EOS® RePure contains no corrosive sulphur.
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Electrical Oil Services has decades of experience in recycling insulating fluids
Recycling is not a new approach for Electrical Oil Services. The company is a pioneer in recycling insulating fluids and has decades of experience in the treatment and recycling of insulating oils.
Through the EOS® Closed Loop model, Electrical Oil Services collects used mineral insulating oils, recycles them and returns them to the value chain. In this way, many millions of litres of insulating oil have already been kept within the recycling loop.
As synthetic esters play an increasingly important role in transformer applications, Electrical Oil Services is now taking the next step. Together with its technology partner TeslaSsorb from the Nikola Tesla Institute of Electrical Engineering, the company has developed the first industrial recycling solution for used synthetic ester transformer fluids.
The solution has already proven itself in practice: a successful trial with 50 tonnes of recycled synthetic ester fluid in live grid operation has been completed. This demonstrates that recycling synthetic ester transformer fluids on an industrial scale is now a reality.
What does EOS® RePure mean for transformer operators?
EOS® RePure does more than provide a recycling route for used synthetic ester. The recycled fluid is designed to return to transformer operation and can be used in all applications in which virgin synthetic ester fluids are used.
For transformer operators, this offers several important advantages:
- Taking sustainability one step further: Recycling synthetic esters is the next step in a sustainable approach to transformer fluids. EOS® RePure is made from recovered synthetic ester, with no fossil content throughout the entire chain.
- 100% recycled content: Used synthetic ester becomes the raw material for a new transformer fluid.
- Virgin-oil quality: Dielectric strength, oxidation stability and viscosity are at virgin-oil level.
- Drop-in ready: EOS® RePure is compatible with existing transformers and requires no retrofit.
- No corrosive sulphur: The recycled fluid contains no corrosive sulphur.
- Established applications: EOS® RePure can be used in the same applications as virgin synthetic ester fluids.
- Reduced footprint: Recycling synthetic ester delivers significant CO₂ savings compared with producing new fluid.
- Closing the loop: Instead of being disposed of at the end of its first service life, synthetic ester is returned to the value chain as a high-quality insulating fluid.
For transformer operators, EOS® RePure therefore combines the technical requirements of an insulating fluid with a circular approach to managing valuable resources.
Would you like to learn more about EOS® RePure or have used synthetic ester transformer fluids recycled? Talk to our experts. We will be happy to advise you.
Conclusion: Electrical Oil Services extends recycling to synthetic esters
With EOS® RePure, Electrical Oil Services is extending its long-standing experience in recycling insulating fluids to synthetic esters. Together with the Nikola Tesla Institute of Electrical Engineering, the company has taken synthetic ester recycling from development to industrial application.
The successful trial with 50 tonnes in live grid operation demonstrates that the solution works in practice. At the same time, EOS® RePure combines 100% recycled content and no fossil content with virgin-oil-level properties and compatibility with existing transformers.
Electrical Oil Services is therefore taking another important step towards a circular approach to transformer fluids: from waste to value, and from disposal to circularity.
Read more about Electrical Oil Services:
- EOS® SERVICES for insulating oils & transformer maintenance
- EOS® Interview: 5 tips for sustainable transformer oil management
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FAQs about EOS® RePures What is EOS® RePure? EOS® RePure is the first 100% recycled ester fluid. Electrical Oil Services produces it from recovered synthetic ester transformer fluids, returning a valuable resource to the value chain. Where can EOS® RePure be used? EOS® RePure can be used in all applications in which virgin synthetic ester fluids are used. It is drop-in ready, compatible with existing transformers and requires no retrofit. Does recycled synthetic ester provide the same quality as virgin ester fluid? EOS® RePure provides virgin-oil-level dielectric strength, oxidation stability and viscosity. It also contains no corrosive sulphur. Why is recycling synthetic ester transformer fluid more sustainable? Recycling keeps used synthetic ester in the value chain instead of disposing of it. EEOS® RePure has 100% recycled content and no fossil content throughout the entire chain. Recycling the fluid also delivers significant CO₂ savings compared with new production. |
