Environmental Engineering Reference
In-Depth Information
System boundary
Coproducts:
Gasoline
Heavy fuel oil
Jet fuel
Petroleum coke
Asphalt
Energy
resources
examples:
Crude oil
Natural gas
Electricity
Coal
Petroleum diesel
life-cycle model
Coproducts:
Natural gas
Production:
Foreign and
domestic crude
oil
Transport:
Diesel to distribution
Urban bus operation:
Diesel
Refining:
Crude oil to diesel
GHGs/air
emissions
Water emissions
Solid waste
Material
resources
examples:
Limestone
Metals
Water
Transport:
Crude oil to
U.S. refineries
FIGure 11.6
Life-cycle of petroleum diesel for use in an urban bus. (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.)
Diesel oil
(other)
10.1%
Jet fuel
9.95%
Heavy fuel oil
6.17%
Petroleum coke
6.04%
Diesel oil
(low-sulfur) 13.4%
Asphalt
3.83%
Lubricants
1.30%
Petroleum feedstocks
3.19%
Gasoline
44.0%
Other
2.0%
FIGure 11.7
Petroleum diesel refinery products, by mass. (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.)
domestic sources. All crude petroleum was transported to diesel refineries in the United States.
This assumption is fair, given that only 4% of petrodiesel entered the United States in a refined state
at the time of this study. On average, foreign crude traveled 7 times farther than domestic crude.
Transportation of foreign crude was 4 times more primary energy-intensive (1.09 MJ/kg for foreign
vs. 0.27 MJ/kg for domestic), mainly attributed to tanker ship transportation.
The refinery model was based on U.S. average data. Over 90% of the refinery's energy was sup-
plied by the crude petroleum entering for conversion to diesel. Refinery products and co-products
are shown in Figure 11.7. This study assumed low-sulfur diesel will be used by the bus. One problem
with the mass allocation method is that it does not identify refinery inputs uniquely required for
diesel production (e.g., a chemical input exclusively needed for diesel production) and specifically
assign their burdens to the diesel fuel. This allocation method may be selected when detailed sub-
process data are not available.
11.2.2.2.2
Biodiesel Model
The Kim and Dale (2005) ethanol study discussed earlier considered the dominant corn-soybean
crop rotation system, but Sheehan et al. (1998) focused solely on soybean production over one grow-
ing season (per year) with no crop rotations. Energy and emissions related to production of capital
