Fuel consumption and emission factors

Trip-speed dependent basis factors for fuel consumption and emissions are taken from the COPERT model using trip speeds as shown in Table 4.1. The factors are listed in Annex 4. For EU emission levels not represented by ac-tual data, the emission factors are scaled according to the reduction factors given in Annex 5.

The fuel consumption and emission factors used in the Danish inventory come from the COPERT IV model. The source for these data is various Eu-ropean measurement programmes. In general the COPERT data are trans-formed into trip-speed dependent fuel consumption and emission factors for all vehicle categories and layers.

For passenger cars, real measurement results are behind the emission factors

for Euro 1-4 vehicles, and those earlier. For light duty trucks the

measure-ments represent Euro 1 and prior vehicle technologies. For mopeds and

mo-torcycles, updated fuel consumption and emission figures are behind the

conventional and Euro 1-3 technologies. For heavy-duty trucks and buses

the experimental basis is computer simulated emission factors for Euro 0-V

engines.

statistics and 2) fuel specific CO

2

emission factors. The aggregated CO

2

emis-sion factor for 2010 is used in combination with the overall EU target of 130 g CO

2

per km in 2015 and 95 g CO

2

per km in 2020 in order to calculate an interpolated time series of type approval related CO

2

emission factors for the years 2011-2014 and 2016-2019 (year specific CO

2

emission factors).

By assuming that the fuel type/engine size specific COPERT IV fuel con-sumption factors for Euro 4 cars relate to cars from 2009, Euro 5 and 6 COPERT corresponding factors for each fuel type/engine size combination are calculated for each year in the forecast period by multiplying the Euro 4 factor with the ratio between the year specific aggregated CO

2

emission fac-tor and the aggregated CO

2

emission factor for 2009. The fuel specific CO

2

emission factors (g per MJ) for gasoline and diesel are finally used to trans-form the km related CO

2

emission factors into fuel consumption factors.

4.3.2 Adjustment for EGR, SCR and filter retrofits

In COPERT IV updated emission factors have recently been made available for Euro V heavy duty vehicles using EGR and SCR exhaust emission after-treatment systems, respectively. The estimated new sales of Euro V diesel trucks equipped with EGR and SCR during the 2006-2010 time periods has been examined by Hjelgaard and Winther (2011). These inventory fleet data are used in the Danish inventory to calculate weighted emission factors for Euro V trucks in different size categories.

During the 2000’s urban environmental zones have been established in Dan-ish cities in order to bring down the particulate emissions from diesel fuelled heavy duty vehicles. Driving in these environmental zones prescribe the use of diesel particulate filters. The Danish EPA has provided the estimated number of Euro I-III urban buses and Euro II-III trucks and tourist buses, which have been retrofitted with filters during the 2000’s. These retrofit data are included in the Danish inventory by assuming that particulate emissions are lowered by 80 % compared with the emissions from the same Euro tech-nology with no filter installed (Winther, 2011).

For all vehicle categories/technology levels not represented by measure-ments, the emission factors are produced by using reduction factors. The lat-ter factors are delat-termined by assessing the EU emission limits and the rele-vant emission approval test conditions, for each vehicle type and Euro class.

4.3.3 Adjustment for biofuel usage

For CO

2

the neat gasoline/diesel emission factors shown in Table 4.3 are country specific values, and come from the DEA. From 2006 and 2008, re-spectively, bio ethanol and biodiesel has become available from a limited number of gas filling stations in Denmark. Following the IPCC guideline definitions, bio ethanol is regarded as CO

2

neutral for the transport sector as such. The sulphur content for bio ethanol/biodiesel is assumed to be zero, and hence, the aggregated CO

2

(and SO

2

) factors for gasoline/diesel have been adjusted, on the basis of the energy content of neat gasoline/diesel and bio ethanol/biodiesel, respectively, in the available fuels.

At present, the Danish road transport fuels only have low biofuel (BF) shares

(Table 4.3), and hence, no thermal efficiency changes are expected for the

fuels. Consequently, the energy based fuel consumption factors (MJ per km)

derived from COPERT IV are used also in this case.

As a function of the current ethanol/biodiesel energy percentage, BF%

E

, (Table 4.3) the average fuel related CO

2

emission factors, emf

CO2,E

(BF%) be-come:

)

% 100

( ) 0 (

%)

(

_,

, ₂

2E CO E E

CO

BF EF BF BF

EF    (3)

Where:

EF

CO2,E

(BF%) = average fuel related CO

2

emission factor (g MJ

^-1

) for current BF%

EF

CO2,E

(BF0) = fuel related CO

2

emission factor (g MJ

^-1

) for fossil fuels

The kilometre based average CO

2

emission factor is subsequently calculated as the product of the fuel related CO

2

emission factor from equation 3 and the energy based fuel consumption factor, FC

CO2,E

(BF0), derived from COPERT IV:

) 0 (

%) (

%)

(

_,

, ₂

2

BF EF BF FC BF

EF

_{CO km}



_{CO E}



_E

(4)

A literature review carried out in the Danish research project REBECA re-vealed no significant changes in emission factors between neat gasoline and E5 gasoline-ethanol blends for the combustion related emission components;

NO

x

, CO and VOC (Winther et al., 2012). Hence, due to the current low eth-anol content in today’s road transport gasoline, no modifications of the neat gasoline based COPERT emission factors are made in the inventories in or-der to account for ethanol usage.

REBECa results published by Winther (2009) have shown that the emission impact of using diesel-biodiesel blends is very small at low biodiesel blend ratios. Until now, the biodiesel percentage content in Danish road transport diesel has been approximately zero, and consequently no bio fuel emission factor adjustments are needed for diesel vehicles as well. However, adjust-ment of the emission factors for diesel vehicles will be made if the biodiesel content of road transport diesel fuel increases to a more significant level in the future.

The fuel related CO

2

emission factors for neat gasoline/diesel, bio

etha-nol/biodiesel, and aggregated CO

2

factors are shown in Table 4.3.

Table 4.3 Fuel-specific CO2 emission factors and biofuel shares for road transport in Denmark.

Emission factors (g/MJ)

Fuel type 1990-2005 2006 2007 2008 2009 2010

Neat gasoline 73 73 73 73 73 73

Neat diesel 74 74 74 74 74 74

LPG 63.1 63.1 63.1 63.1 63.1 63.1

Bio ethanol 0 0 0 0 0 0

Biodiesel 0 0 0 0 0 0

Gasoline, average 73 72.9 72.8 72.8 72.8 71.7

Diesel, average 74 74 74 74 73.9 74

Biofuel share (BF%) of Danish road transport fuels

Fuel type 1990-2005 2006 2007 2008 2009 2010

Bio ethanol 0 0.20 0.33 0.29 0.31 1.75

Biodiesel 0 0 0 0.01 0.14 0.02

In document DANISH EMISSION INVENTORIES FOR ROAD TRANSPORT (Sider 32-35)