Environmental Engineering Reference
In-Depth Information
600
500
Diesel combustion
Diesel fuel transport
Crude oil refining
400
300
Foreign crude transport
Domestic crude transport
Foreign crude production
200
Domestic crude production
100
0
Production
Use
FIGure 11.17
Petroleum diesel life-cycle CO
2
emissions. (From Sheehan, J., et al., Life cycle inventory of
biodiesel and petroleum diesel for use in an urban bus. NREL/SR-580-24089, National Renewable Energy
Laboratory, Golden, CO, 1998.)
600
Biodiesel
combustion
500
Biomass
Fossil
400
300
200
Soybean
agriculture
Soybean
crushing
Soy oil
conversion
100
0
Soybean
transport
Soy oil
transport
Biodiesel
transport
-100
-200
-300
-400
-500
-600
FIGure 11.18
Soybean biodiesel life-cycle CO
2
emissions. (From Sheehan, J., et al., Life cycle inventory
of biodiesel and petroleum diesel for use in an urban bus. NREL/SR-580-24089, National Renewable Energy
Laboratory, Golden, CO, 1998.)
later in this chapter. However, Sheehan et al. (1998) is still one of the more transparent and well-
documented biodiesel LCAs in publication.
11.2.3.4 soybean Biodiesel and renewable Gasoline
Huo et al. (2008) used an updated version of the GREET model to calculate the life-cycle GHG
emissions of four soybean biofuel production pathways, petroleum gasoline, and low-sulfur petro-
leum diesel. In this study, GHG emissions are the sum of CO
2
, CH
4
, and N
2
O emissions, converted
to CO
2
e using IPCC 100-year global warming potential factors (IPCC 2007).
Figure 11.19 shows the well-to-wheel GHG emissions determined for the six fuels by each of
the allocation methods considered in the study and described in Table 11.5. The greatest GHG
savings were calculated with displacement allocation, except in the green diesel system. With the
