By Anthony Coker, Senior Vice President, MIDEL Americas

Recently the USDA awarded M&I Materials the ‘certified biobased’ badge for its MIDEL natural ester fluids, proving what our customers have long known about the sustainability credentials of these biodegradable, fire safe liquids. The award is the latest in a long line of sustainability milestones for our company, noted for its commitment to research and development. As our CEO Giles Salt says, “It feels like we’ve always done this… looking ahead, my sustainability vision for M&I Materials is to build on the great progress we’ve made so far and achieve more verifiable milestones in this critical journey.”

That vision is echoed in the USDA certification. Although this is a recent development, MIDEL natural ester fluids have always met the standards required for bio-based certification. Now that status is official, US-based customers have an added layer of reassurance not only in choosing a long-trusted, fire safe product, but as the most sustainable option for their transformer fleets.

It was in the 1970s when M&I Materials introduced the world to MIDEL 7131 synthetic ester transformer insulating fluid (followed closely by natural ester fluids MIDEL eN 1204 and MIDEL eN 1215). MIDEL ester transformer fluids are used in distribution and power transformers worldwide. Manufactured in the UK, USA, and South Africa, they deliver robust fire safety and environmental capabilities that have made them an established and critical component – particularly as transformer OEMs and utilities are more eager than ever to use sustainable materials and processes in their supply chains.

It seemed like a natural progression of events when the U.S. Department of Agriculture (USDA) awarded its Certified Biobased Product label to MIDEL’s two natural ester transformer fluids – MIDEL eN 1204 and MIDEL eN 1215. The fluids, manufactured in the US and already well-established in the electric power sector, are both extremely fire-safe (K class), readily biodegradable, moisture tolerant and can extend the life of a transformer’s internal paper insulation – qualities absent from conventional transformer fluids such as mineral oil.

Third-party verification of a product’s biobased content is administered through the USDA BioPreferred Program, which aims to increase the development, purchase, and use of biobased products. Biobased products are cost-comparative, readily available, and perform as well as or better than their conventional counterparts. Utilizing renewable, biobased materials displaces the need for non-renewable petroleum-based chemicals. Biobased products, through petroleum displacement, have played an increasingly important role in reducing greenhouse gas (GHG) emissions that exacerbate global climate change. Vernell Thompson from the USDA BioPreferred Program said, “Products from M&I Materials Inc are contributing to an ever-expanding marketplace that adds value to renewable agriculture commodities, creates jobs in rural communities, and decreases our reliance on petroleum.”

However, what’s really important about the USDA badge award is not so much the endorsement of the fluids’ sustainability bona fides but what the award says about the role of ester transformer fluids in an evolving power industry keen to increase grid resilience.

Here’s an example; in 2021 an ethylene manufacturing plant in Louisiana examined one of its transformers and decided to replace its mineral oil insulating fluid with MIDEL eN 1204 natural ester transformer fluid. The transformer in question, a Westinghouse 1500 KVA unit, was used to supply power into the facility’s wastewater treatment plant. The transformer was situated in a remote part of the site, close to a wooded area adjacent to the Mississippi River where any mineral oil spill would cause significant environmental problems; but this was not the only reason a natural ester fluid was deployed. The local experts on transformer servicing advised that the cost of re-processing the mineral oil currently in the transformer would prove to be too expensive, considering all the equipment and processes needed.

The alternative option of replacing the unit with a new transformer would be even more costly. Retrofilling with MIDEL eN 1204 (canola-based fluid) was especially attractive as its superior oxidation resistance (compared to soybean-based ester fluid) allowed easier handling and reassurance in the retrofill process.

Look again at four major themes in that example: Cost considerations. Asset life extension. Fire safety. Environmental protection. Four critical concerns facing transformer fleet managers; and they are driving the push towards replacing mineral oil with esters as the insulating fluid of choice in new and existing transformers.

The details of how ester fluids deliver such meaningful benefits are worth reviewing: MIDEL eN 1215 ester fluid is made from renewable soybean crops, while MIDEL eN 1204 is made from renewable canola crops. Both fluids are biodegradable and fire-safe (K class with fire points greater than 300°C) and deliver excellent performance in sealed transformers. Key differences between the fluids include MIDEL eN 1215’s pour point of -18°C compared to MIDEL eN 1204’s -31°C pour point (making the latter a more effective cold weather solution). Both fluids are deployed around the world; MIDEL eN 1204 was recently specified by Philippines-based transformer manufacturer, First Philec, for its new range of fully recyclable transformers and has been proven effective in many industrial retrofill projects in North America.

The bottom line? Biobased MIDEL natural ester transformer fluids have immediate K-class/fire safety benefits which you don’t get with fluids like mineral oil and other O-class substitutes. Our natural ester transformer fluids are much better for the environment and demonstrably sustainable. These fluids enable transformer manufacturers, electric utilities, and heavy industry to innovate and develop safer, lower total cost and greener power networks for the country.

As I mentioned earlier, the power sector is mobilizing at pace to address the challenges of growing environmental and sustainability mandates and extreme climate events – all with the aim of increasing grid resilience. The supply chain is responding equally as quick, with new transformer insulating fluids recently launched into the market, including oils with a somewhat higher fire point than mineral oil (though not K class) and able to deliver an element of eco-protection. Which brings me back to my company’s long history of innovation and sustainability; we’ve been in the transformer protection market since the 1970s, with a well-established range of ester transformer fluids.

From this perspective, I really have to scratch my head when I see the newer transformer fluids entering the market, because they compromise on fire safety for the sake of biodegradability – prompting me to ask “Why wouldn’t you demand BOTH from a transformer fluid? Why not get K class fire safety AND 100% biodegradability?”

Perhaps the answer is in the nature of industrial innovation and development – products and solutions are developed, brought to market, and the end users make selections and choices that shape the market.

In the end, as the quest for sustainability is taken up by more and more industries, governments, and companies, we will only continue with our legacy of innovation. It’s best encapsulated by our CEO, Giles Salt, when he says, “The focus now is the pursuit of sustainability, and it’s one of the biggest challenges facing economies today. For us, this means we must continue our drive to innovate and develop advanced materials that make the world a better place”.