Introduction

Globally there are three main emission standards for trucks and buses. In addition, there is the Indian emission standard Bharat. The main standards have their origin from Europe, USA and Japan. These standards regulate emission levels of air pollutants, where some contribute to the greenhouse effect. At present NTMCalc only contains emissions factors for trucks complying with the European, Euro standards. The NTM factors are derived from the “Handbook of emission factors” that represents European emissions during real world driving.

Source: https://theicct.org/publications/china%E2%80%99s-stage-vi-emissions-standard-heavy-duty-vehicles-final-rule

In order to better represent global road traffic by heavy duty vehicles NTM has developed vehicle data that include the US EPA standard and the Japanese JP standard. The India Bharat emission standard is at present not included.

In order to include emission factors for trucks sold on the US and Japanese markets NTMCalc derives these real-world traffic data on the emission factors from European trucks by:

• Assessing regulated emission differences between the Euro standard and US EPA and JP standards respectively
• These factors are multiplied with relevant Euro standard

Note that the emission limits in different countries are not directly comparable due to differences in certification test cycles even though the technology used to meet the comparable standards (e.g. Euro VI, EPA2010 and JP2016) is very similar. Moreover, the used method assumes that emissions during real world driving in the different regions correlate in the same way as the levels set by the certification emission limits.  Hence the used approach is a simplification but is a good enough approach until better data suitable for NTMCalc become available.

For emissions not yet regulated in Europe the following assumptions have been done: CH₄ emission factors have been estimated by using the same conversion factors as for total hydrocarbons. N₂O emission factors have been estimated with a 1:1 relationship between the corresponding emission standards. Also, fuel consumption has been estimated with a 1:1 relationship even though Japan, the US and last out the EU have introduced fuel efficiency standards which all use different approaches to reduce the fuel consumption in relation to a set baseline. The 1:1 relationship is motivated by the lack of data for a comparison of average fuel consumption between the emission standards in each region. It is also assumed that these differences most likely are small in relation to other uncertainties involved.

In Table 1 conversion factors for heavy duty trucks to be multiplied with the NTMCalc Euro emission factors are presented for the US and Japanese emission standards. Conversion factors for light duty trucks are presented in Table 2.

Table 1 Conversion factors used to calculate emission factors for US and Japanese heavy duty trucks outgoing from emission factors for European trucks in NTMCalc.

1 2018 no diesel engines but only CNG, Gasoline and LPG engines were certified to meet this standard.

Table 2 Conversion factors used to calculate emission factors for US and japanese light duty trucks outgoing from emission factors for European trucks in NTMCalc.

Method

Heavy duty trucks

In Table 3 legislative emission standards for the US, Japan and the EU are presented. The emission legislation in the US is divided between federal regulations and regulations specific for the state of California where manufacturers optionally may choose to certify engines to the California Optional Low NOx Standards of 0.10, 0.05 or 0.02 g/bhphr. Note that in 2018 no diesel engines were certified to meet the California low NOx standard. For a detailed description of the different regulations, definitions and implementation periods we refer to sources like www.epa.us, Transportpolicy.net and Dieselnet.com.

The conversion factors for US and Japanese heavy duty trucks (see Table 1) have been derived by dividing the emission limits with the corresponding Euro emission limit.

Table 3 US, Japanese and EU emission standards. Unit for US standards is g/bhph (g/kWh within brackets) and for Japan and Europe g/kWh.

1 In 2018 no diesel engines but only CNG, Gasoline and LPG engines were certified to meet this standard.

Light duty trucks

The conversion factors for US and Japanese light duty trucks (see Table 1) have been derived by dividing the emission limits with the corresponding Euro emission limits which are presented in Table 4. The emission limits for Japan and the US are presented in the following method sections for each country.

Table 4 European emission standards for light duty trucks (>1760kg), mg/km.

Japan

The emission legislation in japan is divided between petrol and diesel vehicles. The emission regulations relevant for NTMCalc are presented in Table 5.

Table 5 Emission legislation for light duty trucks, Japan, mg/km.

The conversion factors to be applied in NTMCalc (see Table 2) were calculated by dividing the Japanese emission levels by the corresponding European Levels.

United States

US legislation for exhaust emission does not differentiate between diesel and petrol engines, however, several differences in vehicle definitions, introduction policies and regional differences makes a direct correlation between US and EU emission legislation non straightforward. The US have also adopted a fuel consumption regulation applicable for LDTs.

The emission legislation is divided between national regulations and regulations specific for the state of California. For a detailed description of the different US-regulations, definitions and implementation periods we refer to sources like www.epa.us, www.transportpolicy.net and www.dieselnet.com.

In the US, the EPA defines the LDT vehicle categories to be used within the emission legislation, see Table 6. California uses the same Light-Duty Vehicle definitions as the US EPA.

Table 6 US LDT vehicle definitions.

Emission regulations – US federal

Emission regulations in the US are stated as the highest emissions allowed from new vehicles at the year of full implementation. The regulations are introduced during a time period during which the manufacturers must sell a fleet whose average emissions meet the criteria level for that year. The fleet average criteria are sharpened annually during the introduction period. Presently (2020) the Tier 3 standard is being introduced, starting 2017 with full implementation in 2025.

EPA – Tier 2

The national regulation Tier 2 was introduced 2004 and phased in ending 2007. The regulations stipulate that producers must put out a fleet average emission of maximum 70 mg NOx/mile (43.8 mg/km) through combining the sales of vehicles from the different bins in Table 7. A specific vehicle model might however not emit more than 900 mg NOx/mile (562 mg/ km).

Table 7. EPA Tier 2, Light duty vehicles – light duty trucks. Source: Delphi Technologies, Passenger Cars and Light duty vehicles, Worldwide emissions standards, 2019/2020.

1 Bins 9-11 expired in 2006 for LD vehicles and LD trucks and in 2008 for HLD trucks and MD Passenger vehicles.

2 Pollutants with 2 numbers have a separate certification standard (1st number) and in-use standard (2nd number).

In order to find a typical vehicle emission level to match with the Euro legislation levels, we made the following assumptions:

• We base the comparison on the emission levels stated for the full useful life (120 000 mi or 190 000 km)
• The average fleet limit of 0.07 g NOx/mile is used.
• The other emissions are selected from the same bin 5 as the 0.07 g NOx/mile level.

EPA – Tier 3

The Tier 3 regulation was introduced in 2017 and reaches full implementation in 2025. There are only limits set for the sum of the NOx and NMOG/NMHC emissions, see Table 8.

Table 8. EPA Tier 3 standards. Source: Delphi Technologies, Passenger Cars and Light duty vehicles, Worldwide emissions standards, 2019/2020.

1) In MY 2017-20 PM standard applies only to that segment of a manufacturer’s vehicles covered by the percent of sales phase-in for that model year.

As with Tier 2 manufacturers might certify specific models according to a specific bin with the demand for a fleet average according to the introduction curve presented in Figure 1.

Figure 1. Tier 3 fleet average NMOG+NOx ftp phase-in (mg/mi). Source: Delphi Technologies, Passenger Cars and Light duty vehicles, Worldwide emissions standards, 2019/2020.

For the Euro regulation comparison, we compare with the average US vehicle fleet in use by 2020. This was calculated as the average of the maximum level of the fleet emissions of NMOG+NOx during the previous 3 years with Tier 3 vehicles. Other emissions are assumed to reflect the levels stated for bin 50/70 in Table 8. The NOx – NMOG emissions (of the combined NMOG+NOx emission value) were assumed to be produced in the same proportion as the allowed limits in Tier 2. The actual proportion will vary between the different strategies applied to meet the standards why a wide spread in values in actual emission levels must be considered in detailed studies. Such studies should always be based on vehicle specific emission data and not the more indicative average emission levels presented by emission calculators like NTMCalc.

The emission levels thus yielded are presented in Table 9.

Table 9. US EPA federal emission levels, indicative, (mg/km).

Emission regulations – CARB – California State

The Californa regulations differ from the federal in terms of year of introduction and emission levels, which generally are somewhat lower. The emission standards LEV III presents the same selection issues as experiensed with the federal level concerning phase in periods and fleet average conditions (se previous section). The same methods as in the federal assessment were applied in order to calculate the following emissions levels, intended to be use in the mapping process with Euro standards. The results are presented in Table 10.

Table 10 California emission levels, indicative, (mg/km).

The emission levels presented in Table 10 should be viewed as our estimates of vehicle emissions i.e. they are not equal to the emission regulations and the only purpose with this exercise is to find a basis for comparison between US and EU emission standards. For the 2015 LEVIII we select the situation in 2019 to be used for comparison with the EU standards. As seen in the table the emission levels are projected to be reduced further up to full implementation 2025.

References

Continental (2019) Worldwide emission standards and related regulations – Passenger cars/light and medium duty vehicles

Delphi Technologies (2019) Worldwide emission standards – Passenger cars and light duty vehicles.

 https://theicct.org/sites/default/files/publications/Efficiency_standards_HDVs_EU_Briefing_051618.pdf

https://www.transportpolicy.net/standard/japan-heavy-duty-emissions/

https://www.transportpolicy.net/standard/california-heavy-duty-ghg/

https://www.transportpolicy.net/standard/us-heavy-duty-emissions/

NTM data, assessed by IVL Swedish Environmental Research Institute