Transportation's Role in Reducing U.S. Greenhouse Gas Emissions ...

Transportation’s Role in Reducing U.S. Greenhouse Gas Emissions: Volume 2
• Direct (implementation) cost per tonne—for most strategies, an indicator of
the GHG benefit that will be achieved with a given level of public-sector
investment; and
• “Net included cost” per tonne. This includes both direct costs and whatever
other costs or cost savings the references cited in the report have chosen to
monetize—usually vehicle operating costs.
With some exceptions, costs in this report are expressed in present-year real
dollars (as cited in the data source or reference) without any inflation or
discounting. In a few cases, when cost estimates were particularly old (e.g.,
prior to year 2000), the consumer price index was applied to inflate values to
current year dollars. When calculating cost effectiveness, future-year operating
cost savings for on-road vehicles (but not for off-road vehicles) were discounted
using a discount rate of seven percent. The cost-effectiveness estimates
computed from the Moving Cooler study data are also based on discounting
future vehicle operating cost savings at a rate of seven percent. Costeffectiveness
estimates from other studies cited in this report that included
future cost savings may have used other discounting assumptions.
The cost-effectiveness estimates should be read with caution because they
reflect monetary costs only, and in many cases may not reflect other very
significant benefits or disbenefits to consumers.
Life-Cycle Fuel Emissions Analysis
The analysis of fuel emissions presented in Volume 2, Section 2.0 considers
“well-to-wheel” (WTW) emissions, which includes all three stages of the life
cycle of a transportation fuel (first, feedstock extraction and distribution, and
second, fuel production and distribution, which are collectively known as
“upstream” or “well-to-pump” emissions; and third, vehicle operation, also
known as “downstream” emissions).
The proportion of GHG use associated with vehicle operation versus upstream
emissions can vary significantly be the type of fuel. For example, hydrogen fuel
cells and electric vehicles have no operating emissions since there is no fuel
combustion in the vehicle. The properties of selected fuels and GHG emissions
by life cycle stage are shown in Table A.1. The results shown in the table are
based on an analysis using the Greenhouse Gas, Regulated Emissions, and
Energy Use in Transportation (GREET) model, version 1.8b (released May
2008). This model, developed at Argonne National Laboratory, is one that is
commonly used by EPA and DOE to assess total fuel cycle emissions of
alternative fuel vehicles. The GREET model calculates WTW emissions, which
takes into account emissions from all phases of production, distribution, and
use of transportation fuels (Chien, 2009). A strength of GREET is that the user
A-6