Choice of method

There are two methodological tiers for determining emissions from the use of lubricants. Both Tier 1 and Tier 2 rely on essentially the same analytical approach, which is to apply emission factors to activity data on the amount of lubricant consumption in a country (in energy units, e.g., TJ). The Tier 2 method requires data on the quantities of different types of lubricants, excluding the amount used in 2-stroke engines, in combination with type-specific Oxidised During Use (ODU) factors to activity data, preferably country-specific, while the Tier 1 method relies on applying one default ODU factor to total lubricant activity data (see decision tree, Figure 5.2). Since the default ODU factor is four times smaller for greases than for lubricating oils, using a higher tier method will primarily capture the impact of using actual fractions of oils and greases in the emission calculation. It is considered good practice to use the Tier 2 method when this is a key category.

Tier 1: CO2 emissions are calculated according to Equation 5.2 with aggregated default data for the limited parameters available and the ODU factor based on a default composition of oil and greases in total lubricant figures (in TJ units):

Equation 5.2 Lubricants - Tier 1 method

CO2 Emissions = LC • CCLubricant • ODULubncant • 44/12

Where:

CO2 Emissions = CO2 emissions from lubricants, tonne CO2 LC = total lubricant consumption, TJ

CCLubncant = carbon content of lubricants (default), tonne C/TJ (= kg C/GJ) ODULubricant = ODU factor (based on default composition of oil and grease), fraction 44/12 = mass ratio of CO2/C

Tier 2: The Tier 2 method for lubricants relies on a similar equation, however detailed data on the quantities consumed per type of lubricants use (in energy units, e.g., TJ) and, preferably, country-specific emission factors should be used. The emission factors are composed of fuel type specific carbon content and the ODU factor:

Equation 5.3 Lubricants - Tier 2 method

Where:

CO2 Emissions = CO2 emissions from lubricants, tonne CO2

LQ = consumption of lubricant type i, TJ

CCj = carbon content of lubricant type i, tonne C/TJ (= kg C/GJ)

ODU = ODU factor for lubricant type i, fraction

44/12 = mass ratio of CO2/C

Lubricant i refers to motor oils/industrial oils and greases separately, excluding the amount used in 2-stroke engines.

In both tiers the carbon contents may be the default value for lubricants described in Volume 2 (Chapter 1, Table 1.3), or a country-specific value, if available.

Figure 5.2

Decision tree for CO2 from non-energy uses of lubricants

Figure 5.2

Decision tree for CO2 from non-energy uses of lubricants

Policy Factors

Note:

1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for discussion of key categories and use of decision trees.

Note:

1. See Volume 1 Chapter 4, Methodological Choice and Identification of Key Categories (noting Section 4.1.2 on limited resources), for discussion of key categories and use of decision trees.

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