According to IEA [6,7], in 2021 the global energy- related CO2


emissions per capita were 4.7 tCO2 /


capita. By taking the three recent studies of the German Society for Tribology [8] “CO2


&friction”


(2019), “Sustainability & Wear protection” (2021) and “Tribology & Defossilisation” (2023) together, friction’s share of direct energy-related CO2 range between 6.7-11 GtCO2


or 0.87-1.43 tCO2


capita. On the other hand, the estimated savings by applying measures by tribology and lubrication sciences to reduce friction range between 0.3-1 tCO2


/capita.


Reducing friction and extending longevity provide “easy to implement and industrial strategies for defossilisation” or “societal CO2 because CO2


-sequestration”, savings generated by tribology and


lubrication sciences occur anywhere and anytime, and less energy needs to be generated upstream to move machine elements downstream. With this information in mind, friction reductions and extensions in longevity save upstream carbon emissions because they do not have to be produced upstream, as they are not consumed downstream. Friction reduction and longevity are two of the essential building blocks of sustainability.


Enhancing Longevity Global, energy-related CO2


emissions have reached


the consciousness of the wider audience. Until today, the issue of resources has been circumstantial to the issue of energy-related CO2


-emissions and has


remained a vague one. The consumption of resources of any kind inevitably leads to CO2


emissions from


the process steps “mining, extraction, smelting and processing”. Here it becomes clear that extending longevity through wear protection is just as important for improving material efficiency and conserving


resources as friction reduction is for reducing CO2 emissions as a contribution to energy efficiency.


The average gross ratio, i.e., calculated across all material streams, between the mining, extraction and processing of one ton of primary metal or material and the corresponding CO2 1.36 and 1.82 tons of CO2


[8]. The overall ratio between CO2


eq. emissions is between eq. per ton of material eq. and extracted


tonnages of metals/materials is calculated at 1.38:1 for 2015, if 11.5 gigatons of CO2


eq. greenhouse


gas emissions, as reported in the U.N. Emissions Gap Report 2019 [9, p. XXV & p. 57, ibid], by the material


emissions /


footprint of 8.3 gigatons of metal ores, as reported in the United Nation Environment Report [10].


This does not necessarily mean longer oil change intervals for lubricants, but the improvement of the service life of products through lubricants reduces the CO2


emissions associated with the decrease in


consumption of resources and therefore lubricants and tribology make a recognisable contribution to sustainability. Extending service life of machineries is therefore an attribute of a sustainable lubricating product.


Re-refining


The collection and re-refined of used oils to base oils lower the carbon footprint on a cradle-to-gate basis by 60-80% compared to crude derived base oils [11], which adds sustainable values to lubricants. The re-refining process used and product carbon footprint of the crude oil considered characterise the range in CO2eq


savings. On the other hand,


the main driver is to prevent leakages, spills or improper disposals into waters and soils, because the relation between lubricant release and water and soil quality has been known for many decades and is absolutely undisputed. In consequence, biolubes or environmentally acceptable lubricants (EALs) were prescribed by policies for water sensitive areas, because their persistence is much shorter with significantly reduced aquatic toxicities.


Biogenic resources The perceived notion of ecofriendly lubricants centres around biodegradability or bio-based formulations. Nowadays, only the EN16807 “Biolubricants” requires >25% and the U.S. DA Bio-preferred programme requires a content of renewables between 25% and 72% depending on the application. Renewable contents were discontinued in 2019 with the second revision of the European Ecolabel for lubricants [EC/2018/1702] (See Table 1).


Bio-based lubricants are those created from naturally occurring materials, which include fatty acids (rapeseed or palm oils) and hydroxyl-fatty acids (castor oils). However, ASTM D7074 defines bio-based material(s) as “materials containing carbon-based compound(s) in which the carbon comes from contemporary (non-fossil) biological sources. EN16807 determines the bio-based content by 14C measurement as specified in ASTM D6866 and CEN/


Continued on page 40 LUBE MAGAZINE NO.180 APRIL 2024 39


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