2.G.4 - Use of Lubricants

In source category 2.G.4 - Other Product Use: Lubricants, emissions from both stationary and mobile application of lubricants are reported.

This sub-category comprises the entire use phase including the process stages of input and output. The products or lubricants covered here, are:

• Compressor oils
• Turbine oils
• Gear oils (automotive oils including automatic transmission fluids, industrial-gear oils)
• Hydraulic oils
• Insulating oils
• Machine oils
• Process oils
• Other industrial oils not for lubricating purposes
• Metal working fluids fluids (hardening oils, water-miscible and not water-miscible metal working fluids, anticorrosive oils)
• Greases
• Base oils
• Extracts from lubricant refining

The consumption of lubricants in Germany has remained at a relatively constant level since 1990, apart from a sharp decrease in the crisis years 2009 and 2020. In 2022 the consumption of lubricants falls to the margin of 588456 t after a slight rebound in 2021.

The emissions calculation method follows a Tier-2 approach. It uses national statistical data ^{[Lit. 1]} for the quantities placed on the market specific per lubricant types as activity rate and specific emission factors for each lubricant type. It is assumed that the amount of lubricants placed on the market per year equals the lubricant use (consumption) in the same year.

Along the life cycle of the different lubricant types, different kinds of losses occur. Only some types of losses are of relevance with regard to air emissions and the different lubricants types differ significantly from each other. Relevant emitted pollutants identified for lubricants are NMVOC and CO₂. But only for engine oils used in machinery and in vehicles emission of both could be accounted for due to combustion of a small fraction of lubricating oils directly resulting in CO₂ emissions.

For Insulating oils ^{[Lit. 3, 5]}, Process oils ^{[Lit. 4, 10, 11]}, Greases ^{[Lit. 10, 11]} and Extracts from lubricant production ^{[Lit. 2, 10, 11]} no emissions expected.

All emission factors are are constant in the entire time series. They were determined in a research project (UBA, 2018) ^{[Lit. 14]}.

Table 1: Tier 2 emission factors for specific lubricant-type groups in percent

In 1995 four categories fell away/ceased to exist (Table 2) and three type groups were newly introduced due to modifications/changes in the Mineral Oil Statistics concerning lubricants. A slight adjustment of the procedure for the years 1990-1994 was needed. Table 2 shows the affected categories as well as the ways in which they were handled in the calculation procedure.

Table 2: Handling of categories in the Mineral Oil Statistics, 1990-1994

For activity data, an uncertainty of 5 percent is assumed considering the well developed national statistics.

The emission factors are based on a broad review of literature and results from relevant research projects and have been discussed with senior lubricant experts. The experts suggested using ranges which are provided in the emission factor table 1.

The modifications of the Mineral Oil Statistics in 1995 show no impact of overall amount of lubricants. Only a reclassification of lubricants from unspecified application categories to specified application categories was made. The emissions for the years 1990-1994 could therefore be just up to 25% to high.

No category-specific improvements are planned.

Lit. 1: Official Mineral-oil Data (amtliche Mineralöldaten) of the Federal Office of Economics and Export Control (BAFA).)
Lit. 2: Ökopol. Consultation of different senior lubricant experts and manufacturers: Hamburg, 2017.)
Lit. 3: Zimmermann, T.; Jepsen, D. Return rates for used lubricant oils in Belgium: Study on Waste Oil Return in Belgium; Ökopol, 2017.)
Lit. 4: Jepsen, D.; Zimmermann, T.; Sander, K.; Wagner, J. Erhebung der Struktur des Altölsammelmarktes und Optimierungspotenziale für bessere Altölqualitäten im Kontext der Abfallhierarchie; Hg. v. Umweltbundesamt (UBA). Ökopol: Dessau-Roßlau, 2016.)
Lit. 5: Sander, K.; Jepsen, D.; Zangl, S.; Schilling, S. Stoffstrom- und Marktanalyse zur Sicherung der Altölentsorgung. Forschungsbericht 204 31 32 UBA-FB 000883: Dessau-Roßlau, 2006.)
Lit. 6: Kline & Company. Lubricant Consumption and Used Oil Generation in California: A Segmented Market Analysis: Part II: Collectable Used Oil Availability in California, 2000-2011. published 03/03/2015: Sacramento, CA, USA, 2012.)
Lit. 7: UNEP. Compendium of Recycling and Destruction Technologies for Waste Oils: Osaka, Japan, 2012.)
Lit. 8: VSI. Getriebeöle; https://www.vsi-schmierstoffe.de/index.php.)
Lit. 9: Vidal-Abarca, G. C.; Kaps, R.; Oliver, W.; Escamilla, M.; Josa, J.; Riera, M. R.; Benedicto, E. Revision of European Ecolabel Criteria for Lubricants. Preliminary Report: Sevilla, 2016.)
Lit. 10: Möller, U. J. Altölentsorgung durch Verwertung und Beseitigung; Kontakt & Studium Bd. 253; Expert Verlag: Renningen, 2004.)
Lit. 11: Bartz, W. J.; Springer, G.; Blanke, H.-J. Expert Praxislexikon Tribologie Plus: 2010 Begriffe für Studium und Beruf, 2., völlig neubearb. Aufl. des Lexikons der Schmierungstechnik von G. Vögtle; Expert Verlag: Renningen, 2000.)
Lit. 12: VSI. Grundöle; https://www.vsi-schmierstoffe.de/index.php.)
Lit. 13: Kolshorn, K.-U.; Wiesert, P.; Götz, R.; Rippen, G. Ermittlung von Altölvermeidungspotentialen: UBA-Forschungsvorhaben Nr. 103 60 111; Trischler und Partner GmbH: Darmstadt, 1996.)
Lit. 14: UBA, 2018: Zimmermann, T.; Jepsen, D. (2018) Entwicklung von Methoden zur Berechnung von Treibhausgas- und Luftschadstoffemissionen aus der Verwendung von Schmierstoffen und Wachsen.)

In sub-category 2.D.3.i - Other product use: Use of lubricants in mobile applications, the German air pollutant emisisons inventory includes emissions from the unintentional co-incineration of lubricants in mobile sources.

As emissions from the use of lubricants in stationary machinery result mostly from the evaporation whereas emissions from mobile machinery result mostly from the unintentional co-incineration within the engine, the methods for emission calculation differ widely.

Therefore, the approaches for estimating emissions from these two areas of lubricant application are looked at in separate sub-chapters linked below.

Basically, the amounts of lubricants unintentionally co-incinerated in engines other than 2-strokes is estimated from the annual amounts of fuels used in these engines, excluding the amounts of fuels used for international aviation and navigation.

Here, the majority of lubricant co-incineration takes place in road vehicles. These related amounts of co-incinerated lubricants are calculated directly within TREMOD ¹⁾.

Table 1: Annual amounts of lubricants co-incinerated in mobile vehicles and machinery - excluding 2-stroke engines, in terajoules

source: own estimations and TREMOD ²⁾

The emission factors are derived from chapter 1.A.3.b.i-iv Road transport 2019, Table 3-87 of the EMEP/EEA air pollutant emission inventory guidebook 2019 ³⁾.

These default values were transferred via a NCV of 0.03985 GJ/kg into the following energy-related values:

Table 2: tier1 emission factors for heavy-metal emissions from co-incinerated lubricants, in g/TJ

With default emission factors applied, emissions' trends depend solely on the amounts of unintentionally co-incinerated lubricants (see Table 1).

Table 3: Annual heavy-metal emissions from co-incinerated lubricants, in metric tonnes

Activity data (annual amounts of unintentionally co-incinerated lubricants) have been revised slightly for the entire time series.

Table 4: Revised annual amounts of unintentionally co-incinerated lubricants, in terajoules

On the other hand, the tier1 emission factors applied so far, remain unaltered compared to last year's submission.

Therefore, the canges in the emission estimates reported for this sub-category result solely from the named revisions in activity data.

Although there are no improvements planned for this specific sub-category, several routine model revisions are scheduled for mobile sources with impact on fuel consumption data and, hence, the amounts of unintentionally co-incinerated lubricants.

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