Appendix 2.3 - Heavy Metal Exhaust Emissions From Mobile Sources

This appendix chapter provides additional information regarding the approaches applied for estimating exhaust heavy metal emissions from mobile sources in:

• Road Transport (1.A.3.b i - iv)
• Non-road Mobile Machinery in 1.A.2.g vii, 1.A.4.a ii/b ii/c ii, and 1.A.5.b
• Railways (1.A.3.c)
• Maritime Vessels and Ships in 1.A.3.d i, 1.A.3.d ii, 1.A.4.c iii and 1.A.5.b
• Aircraft in 1.A.3.a and 1.A.5.b

For heavy-metal exhaust emissions (other then lead from leaded gasoline), energy-related tier1 values have been derived from mass-related tier1 defaults provided in the 2023 EMEP/EEA Guidebook in chapter 1.A.3.b (Update 2024), page 99, table 3-82, taking into account not only the fuel heavy-metal content, but also the contribution of engine wear (“These values have been calculated by encompassing the impact of engine wear to the heavy metal emissions. Therefore, by multiplying these apparent factors with fuel consumption, it is expected that the combined emissions of fuel and engine wear are estimated.”)

From these default values, the following country-specific energy-related tier1 EF were derived via the average NCVs of the fuels used:

Table 1: Tier1 emission factors derived from EMEP/EEA Guidebook 2023 defaults, in g/TJ

Here, biodiesel has a slightly lower NCV compared to fossil diesel resulting in higher emissions per TJ, whereas for biogasoline the same NCV is applied as for fossil gasoline.

In addition, the EMEP/EEA Guidebook provides separate values for heavy metals from the unintended co-incineration of lube oil. The latter are reported in NFR sub-category 2.G.4 as emissions from product use. (Note: This country-specific approach has been discussed and accepted at both the 2018 TFEIP meeting and the 2018 NEC review.)

Without country-specific information, tier1 values are applied.

However, instead of using the emission factors provided in (EMEP/EEA, 2023) ¹⁾, Table 3-1 Tier 1 emission factors for off-road machinery,…

…the EF for exhaust HMs from NFR 1.A.3.b.i-iv (see above) are applied in order to assure the separate reporting of emissions from fuel and engine wear and the unintended co-incineration of lube oil:

Table 2: Tier1 emission factors derived from EMEPEEA Guidebook 2023 defaults for NFRs 1.A.3.b i-iv, in g/TJ

Furthermore, as stated in the 2023 EMEP/EEA Guidebook, similar EF are applied for land based military vehicles and mobile machinery as part of NFR 1.A.5.b:

Heavy-metal emissions from lubricants (as far as not used in 2-stroke mix) are reported under NFR sub-category 2.G.4 as emissions from product use.

Tier1 default EF as provided in the corresponding chapter of the EMEP/EEA Guidebook 2023:

Besides these emissions from fuel combustion and engine wear, the German inventory also covers abrasive emissions from brakes, wheels on rail and contact line. Here, a country-specific approach is applied with emissions of (i) chromium and nickel being estimated as part of the particle emissions from brake wear whereas emissions of copper (ii) copper are estimated as part of the PM emissions from the contact line.

Table 4: Country-specific emission factors for abrasive emissions, in g/km

Table 5: Tier1 default emission factors applied to inland ships and vessels, in g/TJ

Tier1 default EF as provided in the corresponding chapter of the EMEP/EEA Guidebook 2023:

From these mass-related default emission factors, energy-related tier1 EF were derived via average NCVs for the fuels used:

Table 6: Tier1 emission factors derived from EMEP/EEA Guidebook 2023 defaults, in g/TJ

These “country-specific” values are similarilly applied for exhaust HMs from ships and vessels in NFR categories 1.A.3.d i, 1.A.3.d ii, 1.A.4.c iii, and 1.A.5.b.

The EMEP/EEA Guidebook 2023 does not provide specific default values for heavy metal emissions from the combustion of jet kerosene and aviation gasoline, stating that for aviation gasoline these emissions are not estimated (NE):

Therefore, the inventory compiler decided to adopt the tier1 EF from gasoline fuel used in non-road mobile machinery as a proxy. Although the Party assumes that HM emissions are also likely to occur from the combustion of jet kerosene, no gap-filling is carried out for this fuel. Instead, all heavy metal emission from jet kerosene are reported as not estimated (NE).

Table 7: Tier1 default emisison factors applied to aircraft, in g/TJ