GRIP CEE 2017 / Main Report

5.4 Emissions Evaluation

5.4.1 GREENHOUSE GAS EMISSIONS

The two main approaches to greenhouse gas (GHG) evaluation of vehicles present- ed in this chapter are: \\ JEC (Joint Research Centre) Methodology Versions 2.c (March 2007) and 4.a (January 2014) (Figure 5.6), which use the 5-seat C segment passenger car as a reference vehicle \\ DLR (Deutsches Zentrum für Luft und Raumfahrt) & Partners (July 2013) (Figure 5.7), which use mid-size passenger car and city bus as reference vehi- cles Both methods work with an overall balance of “well to wheels” (WTW), which accounts for production and transmission (well to tank – WTT) and consumption (tank to wheel – TTW) of the fuel, closely described in Figure 5.5. It should be mentioned that these studies comprise all emissions causing the greenhouse effect including, but not limited to, CO ² , N ² O, and CH 4 . Methane (CH 4 ) is an especially potent greenhouse gas. Thus, any loss of unburned NG during exploitation, transmission, and distribution must be strenuously avoided.

Well to wheels

Tank to wheel

Well to tank

Feedstock production

Transmission

Refining

Distribution

Consumption

Natural Gas

Figure 5.5: Well to wheels lifecycle diagram

As shown in Figures 5.6 and 5.7, GHG emissions per kilometre were in 2010 (JEC) and 2012 (DLR) about the same for CNG and diesel vehicles, as resulted from both evaluation methodologies. However, both evaluation methodologies predict a trend that the GHG emissions of CNG vehicles in the future will undercut the GHG emis- sions of diesel. While the JEC predicts a gap of 3.8% in favour of CNG vehicles in the year 2020, the DLR predicts a gap of 9.8% in favour of CNG passenger vehicles and even a gap of 14.3% in favour of CNG buses by the year 2030. The specific CO ² emission per kWh given in Table 1 suggests a gap of 26%. This theoretical value, however, is reduced, because the energy efficiency of a diesel- fuelled compression ignition engine is actually higher than the efficiency of a NG- or petrol-fuelled spark ignition engine, which is indicated in previous paragraph. For the same reason, compared to petrol-fuelled engines, NGVs by contrast actually demonstrate a positive advantage of 20% regarding GHG emissions. The DLR result for CNG buses is especially encouraging, and it confirms ongoing projects in Bulgaria and Germany for NG-fuelled buses and garbage collection trucks in urban areas.

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Central Eastern Europe GRIP 2017

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