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TN 13 NTM Overview of diesel emission factors

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NTM 20200821 Diesel WTW

Fossil diesel is often used as a benchmark in climate impact calculations when, for example, the environmental benefits of bio-based fuels are demonstrated. However, the WTW emission factors from fossil diesel that are used as baseline can differ depending on the data source, calculation method adopted and underlying assumptions.

Here, a compilation of data for fossil diesel from different data sources is presented and key differences are briefly discussed. Results and emission factors are presented in terms of gr CO2 eq. per MJ fuel. The system boundaries are set to a Swedish and EU perspective. For additional information and emission factors see Additional picture by the end of this document.

Discussion on the results

Three groups or types of diesel were identified in this overview: diesel MK1 (commonly sold on the Swedish market), MK3 (sold on the European market) and baseline models presented by REDII and the Swedish Energy Agency. Diesel MK1 sold on the Swedish market in 2018 contained 23% biofuels (FAME and HVO) and have increased over the last years (SEA, 2019). Diesel MK3 contains none or very little biofuels. The share of renewable components in the final fuel may therefore affect the estimated values.

Apart from the differences in the share of biofuels described above, the location of diesel production (from oil extraction to refining as well as associated transports) as well as the method used for accounting for the by-products during the refining process (i.e. allocation procedure) may impact the WTT value. In the JRC-Well to Tank – report system expansion with product substitution is used (assuming marginal diesel production) when calculating the impact of diesel production and thus resulting in a higher impact (14-15 g CO2eq per MJ fuel).  Other reports using an allocation procedure based on energy content result in lower values (6.6-12 g CO2eq per MJ/fuel). The study by Hallberg et al 2013 for MK1 represents Nordic and Swedish conditions for diesel production and distribution thus lower values are expected.

The values for TTW does not vary to the same extent as the values for WTT as they range between 70-76 g CO2eq per MJ. The differences are due to the share of biofuels but may also be caused by the mode of transport (passenger car, heavy duty trucks, Euro-class emission standards). For this literature overview, only recent emission standards were assessed (EURO5 to EURO6).

Finally, the emission factors used in the impact assessment process may also lead to variations.  In this study the emissions factors for GWP (climate impact) from the IPCC Fifth Assessment Report (AR5) were used: 1 (CO2), 28 (CH4) and 265 (N2O) for a 100 years’ time horizon. References which only publish WTW results in CO2 eq. may be using other emission factors when calculating the climate impact.

Closing remark and comparison to NTM Calc.

The values used in the current version of NTM Calc. 4.0 are based on the study by Hallberg et al 2013 for the Swedish conditions (MK1) while the data for EU diesel are based on average data from European datasets (as calculated in Hallberg et al.).

The WTT data for MK1 can be representative to the Swedish conditions which are in general lower than average EU. TTW data for MK1 were delivered by IVL and are still considered relevant to use. Thus, no significant changes can be expected at this stage.

In total, the WTW data for MK1 are slightly higher than the data reported by the Swedish Energy Agency but that is due to the renewable content of the various fuels in the Swedish market (which affect mainly the TTW emissions). Data on B0, which corresponds to MK3, are aligned with the Swedish Energy Agency. The impact from MK1 used in NTM calc is lower than the baselines presented by REDII. NTM could consider presenting different MK1 compositions that could include a renewable share.

 

Additional data

 

References

European Commission (EC) (2018). “DIRECTIVE (EU) 2018/2001 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of December 2018 on the promotion of the use of energy from renewable sources (recast).

Hallberg, L., et. al., (2013) Well-to-wheel LCI data for fossil and renewable fuels on the Swedish

market. Report No 2013:29, f3 The Swedish Knowledge Centre for Renewable Transportation

Fuels, Sweden. Available at www.f3centre.se.

Edwards, R et al. (2014) Well-to-Wheels analysis of future automotive fuels and powertrains in the

European context, Version 4a, Joint Research Centre (JRC), Ispra, Italy

Swedish Energy Agency (2019) Drivmedel 2018 – Redovisning av rapporterade uppgifter enligt drivmedelslagen, hållbarhetslagen och reduktionsplikten. ER 2019:14. Available at http://www.energimyndigheten.se/fornybart/hallbarhetskriterier/

NTM data assessed by IVL Swedish Environmental Research Institute