Introduction There is certainly a lot in the media about the Environment impact of humans, especially around carbon footprint of almost everything we do, make or use.
While it is exciting to live in an energy transition era caring so much more about the environment, this overwhelming flow of information contains its share of voluntary and unvoluntary misleading claims requiring proper scrutiny to unveil them. Such “greenwashing” is unfortunately becoming frequent despite new legislation addressing it, distracting us from our focus on assessing the full environmental impact (and not just CO2) based on relevant and proven data.
In fact, the most respected environmentalists themselves complain about the excess focus on CO2 (and CO2 equivalent) with the risk of neglecting other impacts.
For instance, the Stockholm Environmental Institute www.sei.org, calls for a stop to “carbon tunnel vision” highlighting a range of other criteria in measuring environmental footprint. Inspired by Jan Konietznko’s original graphic Not every environmental impact is quantifiable in CO2eq, far from it! This is why international standards on Life Cycle Assessment (LCA) insist on choosing a number of relevant Impact Categories and not just CO2 or Global Warming Potential.
The energy industry is no exception, and it is increasingly difficult and time-consuming for practitioners at all levels in power systems and transformers to decipher “green” claims and what exactly would or would not support their environmental objectives while of course still delivering on technical and economic performance.
Sadly, a narrow focus on CO2 footprint on part of a product life only is often “convenient” to some as we discovered, while the true Environmental Footprint is found in an LCA across multiple impact categories.
With the above in mind, the recent introduction of new types of transformer oils such as natural and synthetic esters has prompted us to compare their environmental footprint to the long-established mineral oils, both new and regenerated.
Our findings
To do so, we chose to follow the guidelines of globally recognised standards ISO 14040 and ISO 14044 for LCA.
After defining the goal, scope, system boundaries and functional unit (1kg of oil) as per standards, a key step lies in choosing the Impact Categories against which the products will be measured to assess their environmental footprint over their life cycle. Table 1 highlights the impact categories chosen. Table 1: Impact categories in a Life Cycle Assessment of transformer oil As we extensively screened the existing scientific literature, international databases (Simapro, Agri-Footprint) and other publications, we realised even more how insufficient direct CO2-eq emissions are to quantify these oil environmental impacts. Additionally, when looking at CO2, as table 1 describes, for plant-based materials, their Land Use Change (LUC) can be a critical CO2 contributor that is sometimes easily or “conveniently” omitted. LUC must therefore be included in the GWP. Avoid the Carbon Carousel: Carbon in, carbon out…
In a plant-based product such as natural ester transformer oil, only accounting for the CO2 absorbed during plant growth to promote its environmental friendliness is fundamentally misleading for 3 main reasons:

First, their LUC or “what was growing there prior to soybean crops?” Was it rainforest for instance? If so, land agriculture then receives a CO2 penalty equivalent to the amount of CO2 that was absorbed by pre-existing flora minus the much smaller amount absorbed by this new agriculture. As if we needed CO2 accounting to tell us that deforestation was wrong!
Secondly, promoting the CO2 absorbed in a “cradle-to-gate” approach is contrary to any LCA where carbon emissions must be calculated over the product lifecycle, which therefore includes end-of-life, that is, when the carbon absorbed goes back to the environment whether through burning, biodegradation or other types of decomposition.
Most importantly, as per leading global standards, protocols or conventions, carbon has to be locked away for at least 100 years for any meaningful contribution toward climate change. Short-term carbon sequestration is climate-neutral at best, misleading at worst.

Furthermore, when products last less than 100 years, the benefits of a circular economy (where possible) become even more so relevant such as the regeneration of mineral transformer oils delivering overwhelming CO2 reduction.   Decarbonization vs Deforestation Figure 1 was published by a leading foundation dedicated to the sustainability of the feed and food production (www.proterrafoundation.org). It shows that the carbon footprint of soybean including LUC can be 20 to 40 times higher than without LUC in countries like Argentina, Brazil, and Paraguay due to deforestation. Fig 1: CO2 footprint of soybean including LUC Fig 2: CO2 footprint of different soy products The same reference also shows in Figure 2, the comparative carbon footprint of different soy-based products. In this case, the oil shows by far the highest CO2 footprint due both to its processing and its relative high value vs other soy products.
In our research, as we examined natural esters made from soybean and rapeseed oil, we observed significantly differing CO2 emissions values for both depending on sources and authors’ choice of assumptions and parameters such as geography, LUC, transport and process. Therefore, for the CO2-eq excluding LUC, we have used an average of the values found which are in agreement with other published values. Fig 3: soybean deforestation in the region of Gran Chaco, south America – Courtesy WWF Figure 4 shows the results of our life cycle analysis across the 6 impact categories of table 1.
Following on previous remarks, in the top left quadrant, we show the GWP without LUC to which we then added the LUC based on the weighted average of country-related LUCs to their soybean productions. They are conservative numbers in the sense that using LUC from South America-grown soybean would show much higher GWP, more in line with figure 1 since Argentina, Brazil and Paraguay together account for over 50% of the world soybean production. Soybean-induced deforestation is of major concern in these countries as reported by the most respected organisations and academics such as WWF, the London School of Economics, the Earth Observatory, the Stockholm Environmental Institute (via Trase) etc.
In the case of synthetic esters, the values can vary depending on raw materials used (acid and alcohol), one of which can either be source from plant or petroleum.
Other impact categories show the systematic higher impact of crops due to their extensive land culture, using a lot of water, fertilisers and other chemicals potentially leading to higher acidification, eutrophication and ecotoxicity.
This composite picture also shows that mineral oil impact can be tremendously reduced by the proper recycling, also called regeneration and reuse of mineral transformer oil in a circular economy. As many other natural resources such as various metal ores, petroleum, when not used as fuel, can be the source of precious products which can be used and reused many times. Fig. 4: Comparative Environmental Footprint of transformer oils across key impact categories Biodegradable does not mean environmentally friendly: it is essential to avoid terms such as “green” (except in greenwashing!), or misleading terminology such as “environmentally friendly” without specifying what specific property it relates to. Biodegradability is too often translated into environmental friendliness, and while biodegradability is reassuring in case of accidental spillage, it does not mean environment friendly; the example of palm oil would resonate with many as we have been sensitized to other detrimental environmental impacts of some palm culture.
Conclusion:
Common sense is not so common as often said. As practitioners in the energy industry, it is essential that we research and question new topics such as the true environmental impact of products and activities.
In the case of transformer oil, we showed that accepting CO2 footprint messages on face value can be misleading and not only constitute a greenwashing offense in many jurisdictions, but could influence the decisions making of individuals and organisations ending up causing more harm to the environment.
Key takeaways:

Discard incomplete analysis such as “cradle to gate”; focus on LCA, i.e. “cradle to grave”, or even better the Circular Economy (“cradle to cradle”)
Environmental footprint across Impact Categories as per standards is paramount, and not just CO2 alone which can carry an incomplete picture either by ignorance or as misleading tactics.
Negative carbon footprint is rarely real! In all recognised standards such as ISO 14067, GHG protocol or PAS-2050, embedded carbon often called biogenic, e.g. absorbed by plants, should not be accounted for unless it is sequestered for 100 years or more to have any meaningful impact on climate change! This is simply because at end of life (burning or decomposition), a product would re-emit the carbon captured, hence leading to a nil sum (while manufacturing and product use would have a positive CO2 footprint)

Without applying such key principles, the risk for misconception or even greenwashing is high as regularly observed in the media, especially in the case of natural ester transformer oil often presented as a “carbon negative” product. It is furthermore qualified as environment-friendly because it and is biodegradable which h as explained above is grossly misleading. Palm oil being a striking counterexample.
In summary, we showed in our Life Cycle Assessment that in the case of transformer oils, when recycled into transformer oil or other worthy oil product (not to be burnt), mineral transformer oil has by far the lowest impact on the environment. Conversely, natural ester demonstrated the highest detrimental environmental impact in almost all impact categories. Philippe Reboul completed his Engineering at Ecole Centrale, France and his Master of Science (Honours) at Lyon University.
He’s worked most of his career in base oil, lubricants around the world and for over 12 years in transformer oil across Australia & New Zealand, now handling all types of insulating fluids as Director of Molekulis.
Philippe is an active member Cigre NZ and Cigre Australia A2 panel, and also sits on Standards Australia EL-008 Power Transformer committee while being involved with the Australasian Transformer Innovation Centre at the University of Queensland and the Electric Energy Society of Australia.