Document ID: EPA-HQ-OAR-2005-0161-3173
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2010-03-26T04:00Z

February 1, 2010

MEMORANDUM

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

SUBJECT:	Fuel-Specific Lifecycle Greenhouse Gas Emissions Results

This memorandum accompanies 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 the
renewable fuels considered under this rulemaking.  Our analysis of
fuel-specific lifecycle GHG emissions utilized several data sources and
models, as explained in the preamble and Chapter 2 of the Regulatory
Impact Assessment (RIA).  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 three separate categories of tabs to
calculate the lifecycle GHG results.

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 RIA 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.  Results tabs are also
included for the high and low land use change estimates based on the
uncertainty analysis conducted for this rulemaking.  

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.

Most spreadsheets also include results calculations for the years 2012
and 2017 as well.  Many of the results spreadsheets include high and low
estimates which form a 95% confidence interval around EPA’s central
estimates.  The confidence intervals are based on EPA’s quantification
of the uncertainty in projected international land use change emissions
impacts.  For the corn ethanol and biodiesel there are separate
spreadsheets that include results for a high yield sensitivity case. 
Each spreadsheet also contains a number of summary information and
charts that are discussed in the RIA Chapter 2.  For more information
see the RIA Chapter 2.

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

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