Environmental Engineering Reference
In-Depth Information
1
Electricity
Steam
Natural gas
0.8
0.6
0.4
0.2
0
Receiving
and storage
Bean
preparation
Oil
extraction
Meal
processing
Oil recovery olvent
recovery
Wa ste water
treatment
Degumming
FIGure 11.9
Relative energy requirements of soybean crushing processes. (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.)
0.25
0.25
0.2
0.2
Diesel fuel
transport (3%)
Crude oil
refining (60%)
Biodiesel
transport (2%)
Soy oil
conversion (35%)
Soy oil
transport (3%)
Soybean
crushing (34%)
Soybean
transport (1%)
Soybean
agriculture (25%)
0.15
0.15
Foreign crude
transport (7%)
Domestic crude
transport (2%)
0.1
0.1
Foreign crude
production (11%)
Domestic crude
production (18%)
0.05
0.05
0
0
Petroleum
diesel
Soybean
biodiesel
FIGure 11.10
Primary energy inputs of petroleum diesel and soybean biodiesel production. (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.)
11.2.2.2.4
Results
More primary energy (60%) is associated with crude oil refining than any other phase in the life-
cycle of petroleum diesel, per megajoule of fuel delivered. In the soybean biodiesel system, conver-
sion of the oil to biodiesel required more than one-third of the total primary energy (excluding the
energy content of the fuel itself). The primary energy requirements of each system are shown in
Fig u re 11.10.
Although crude oil refining required most of the primary energy in the petroleum diesel model,
it was not examined with sensitivity analysis. A recent assessment (Wang 2008) reported aver-
age U.S. petroleum refinery energy efficiency as 88% and refinery diesel output by mass fraction
