October 30, 2008

MEMORANDUM

TO: 			Air Docket EPA-HQ-OAR-2005-0161

SUBJECT:	Fuel-Specific Lifecycle Greenhouse Gas Emissions Results

This memorandum accompanies six spreadsheets containing fuel-specific
lifecycle greenhouse gas (GHG) emissions results placed on the docket
for this rulemaking under the same docket number.

The spreadsheets that accompany this memorandum contain results for six
major types of renewable fuels: corn ethanol, corn stover ethanol,
imported sugarcane ethanol, soy-based biodiesel, switchgrass ethanol,
and waste grease biodiesel.  Our analysis of fuel-specific lifecycle GHG
emissions utilized several data sources and models, as explained in the
preamble and Chapter 2 of the Draft Regulatory Impact Assessment (DRIA).
 The spreadsheets that accompany this memorandum integrate results from
all stages of the fuel lifecycle to calculate fuel-specific lifecycle
GHG reductions.  The fuel-specific GHG reductions are calculated as
percent emissions reductions compared to a 2005 petroleum baseline.

The docketed spreadsheets use four separate tabs to calculate the
lifecycle GHG results.

The Scenario tab describes the volumes of renewable fuels modeled in the
control case and fuel-specific cases.  Lifecycle GHG results are
estimated per million British Thermal Units (mmBtu).  The increase in
renewable fuel production modeled for each fuel is the difference
between the Control Case volume and the fuel-specific case volume.

The Plant Types tab lists the types of fuel production facilities
analyzed for each of the major renewable fuel types.  For example, 34
production facility types were analyzed for corn ethanol.  This tab
shows the energy sources, plant features, and fuel production GHG
emissions for each plant type analyzed.  For more information about fuel
production GHG emissions estimates refer to DRIA Chapter 2.

The Results_2022 tab includes the annual emissions, starting in 2022,
produced during each stage of the fuel lifecycle, including annual GHG
emissions from ten components of the fuel lifecycle.  The reader can
change the time horizon and discount rate applied to emissions to see
how these factors effects the final results.

The LUC_2022 tab contains a calculation of indirect international land
use change emissions produced by renewable fuel production.  The crop
expansion reported in this tab comes from the FAPRI model.   The land
use change emissions factors were calculated using data provided by
Winrock International Inc.

The corn ethanol and biodiesel results spreadsheets also include results
calculations for the year 2017 for biodiesel, and 2017 and 2012 for corn
ethanol.  There is also a spreadsheet that shows results for a scenario
with a larger change in corn ethanol volumes. Each spreadsheet also
contains a number of charts that are discussed in DRIA Chapter 2.  For
more information see DRIA Chapter 2.

 The FAPRI model projections are described in detail in DRIA Chapter 2,
and detailed result are provided in spreadsheets that were docketed
separately.

 The Winrock calculations are discussed in detail in DRIA Chapter 2, and
spreadsheets with the calculations were docketed separately.

