June 28, 2011

MEMORANDUM

TO:			Air and Radiation Docket EPA-HQ-OAR-2011-0542

SUBJECT:	Supplemental Information for Renewable Gasoline and Renewable Gasoline Blendstock Pathways Under the Renewable Fuel Standard (RFS2) Program 

This memorandum summarizes the lifecycle GHG results from modeling the renewable gasoline and renewable gasoline blendstock pathways.


Summary of Lifecycle Results
Figure 1 illustrates the lifecycle GHG emissions results from the renewable gasoline and renewable gasoline blendstock modeling.  It shows the percent difference between lifecycle GHG emissions in 2022 for the pathways as compared to the 2005 petroleum gasoline fuel baseline.  Results from the RFS2 final rule for the cellulosic F-T diesel pathway are also shown for added context.  
      Figure 1: Lifecycle GHG Emissions Results from RFS2 Final Rule and 
Renewable Gasoline and Renewable Gasoline Blendstock Pathways Using Corn Stover 
                               (g CO2-eq./mmBtu)

* Approximated based on biochemical cellulosic ethanol process from RFS2 final rule
Table 1 below breaks down by stage the lifecycle GHG emissions for the cellulosic pathways and the 2005 petroleum baseline.  The table demonstrates the contribution of each stage in the fuel pathway and its relative significance in terms of GHG emissions.  

                                       
Table 1: Lifecycle GHG Emissions for RFS2 Cellulosic Pathways and Cellulosic Gasoline Pathways Using Corn Stover, 2022 (kg CO2-eq./mmBtu)
                                   Fuel Type
                            2005 Gasoline Baseline
Direct Biochemical Fermentation to Renewable Gasoline and Renewable Gasoline Blendstock**
                     RFS2 Final Rule Cellulosic F-T Diesel
             Catalytic Pyrolysis to Renewable Gasoline Blendstock
      Biochemical Fermentation to Renewable Gasoline via Carboxylic Acid
Net Domestic Agriculture (w/o land use change)
                                       
                                      ~11
                                      11
                                       9
                                       8
Domestic Land Use Change
                                       
                                     ~-11
                                      -11
                                      -9
                                      -8
Fuel Production 
                                      19
                                 < or = -33
                                       5
                                      28
                                      30
Fuel and Feedstock Transport
                                       *
                                      ~2
                                       3
                                       2
                                       2
Tailpipe Emissions 
                                      79
                                      ~1
                                       1
                                       2
                                       2
Total Emissions 
                                      98
                                 < or = -29
                                       9
                                      32
                                      34
*Emissions included in fuel production stage.
** Approximated based on biochemical cellulosic ethanol process from RFS2 final rule.
