Methodology

The evaluation was conducted in three phases: first the production of the fuel up to the point it reaches the vehicle tank, Well-to-Tank (WTT); second consumption of the different fuels by vehicles, Tank-to-Wheel (TTW) and; third the integration of the two previous evaluations, providing the complete Well-to-Wheel (WTW) impact of each combination.

3.1. Well-to-Tank

For this phase, a life cycle analysis software was used, GABI [1], using the information available in its database and country specific information when available. The analysis considers only emissions of gases that contribute to the greenhouse effect, C02, CH4 and N20.

The following values where considered regarding sources of crude (Table 1) and fuel properties (Table 2).

Table 1. Energy resource properties [1] [4].

LHV

C02 content

MJ/kg

MJ/Nm3

g/MJ

Crude Western Africa

42,4

72,8

Crude Middle East

42,6

72,8

Crude South America

41,7

72,8

Crude Mediterranean

43,5

72,8

Crude CIS

42,2

72,8

Crude North Sea

42,7

72,8

Natural Gas Algeria

33,8

56,4

Table 2. Fuel properties [l] [4].

LHV

C02 content

MJ/kg

MJ/Nm3

g/MJ

Diesel

43,0

72,8

Compressed Natural Gas

33,8

56,4

Hydrogen

119,3

0

For quantification purposes, the emissions of the three GHG are presented in gram of C02 equivalent, based on the IPCC tables of Global warming potential (Table 3).

Table 3. Global warming potential [8].

Greenhouse gas

g C02 equivalent per g

C02

1

CH4

21

n2o

310

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