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6.0  Emission Calculations

Emissions per unit of fuel were calculated for the fuel and feedstock combinations discussion in Section 3.

Results are shown here for the year 2010 corresponding to Scenarios 2 and 3.  The results for average emissions and for 1996 are included in Volume 2.  The results were organized according to fuel economy cases presented in Section 5.

Table 6-1 shows the marginal NMOG emissions for Scenario 2 on a g/gal basis (per kWh for electric power).  These emissions represent the values for the different fuel production and distribution phases discussed in Section 3.  Many of the emission sources were estimated to be zero on a marginal basis.  Crude oil extraction and transport emissions would not change with additional diesel or LPG usage.  It is assumed that additional finished fuel is transported to the SoCAB to represent the marginal fuel input to refineries.  In the case of diesel, the mix of refinery operations would be adjusted to accommodate an increase in diesel production.  Such a switch is typically performed on a larger scale in the winter for some refineries when they produce more home heating oil and less gasoline.  Marginal feedstock transport and fuel production emissions in the SoCAB are zero for methanol and FTD production from remote natural gas. When landfill gas is converted to methanol, additional emissions would be produced from the methanol plant but net emissions from the landfill would be reduced or zero.  The NMOG emissions for LPG transport are much higher than those for other fuels.  These emissions correspond to the outage value losses from distribution storage tanks, tank trucks, and local fueling stations.  This source was assumed to be controlled in Scenario 3.

Table 6-2 shows the marginal emission estimates for Scenario 3.  In this scenario, additional emission controls were assumed.  The most significant emission reduction assumptions were vapor recovery on methanol and diesel fueling equipment and reductions in spillage emissions per ARB's new rules for enhanced vapor recovery.  A 90 percent reduction in emissions could be accomplished with on-board vehicle refueling vapor recovery.  A lower emission factor for fuel spillage was also assumed.  This scenario does not take into account the use of larger vehicle fuel tanks to extend range and reduce spillage emissions.

Tables 6-3 and 6-4 show the emissions for Scenarios 2 and 3 on a g/mi basis.  Fuel economy assumptions b and c were applied to g/gal values.  The results are also shown in Figures 6-1 and 6-2.  These g/mi representations straddle the high and low estimates for Case B.

Table 6-1:  Marginal NMOG Emissions per Unit Fuel:  Scenario 2

NMOG Emissions (g/gal)

g/kWh

Fuel-Cycle Process

Diesel

RFD

LPG

FTD

M100 NG

M100 LFG

Electric

Feedstock transport

0.0000

0.0000

0.0000

0.0000

0.0000

0.0000

0.0007

89

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