Transportation Demand Module
The NEMS Transportation Demand Module estimates energy consumption across
the nine Census Divisions (see Figure 5) and over ten fuel types. Each
fuel type is modeled according to fuel-specific technology attributes applicable
by transportation mode. Total transportation energy consumption is the
sum of energy use in eight transport modes: light-duty vehicles (cars and
light trucks), commercial light trucks (8,501-10,000 lbs gross vehicle
weight), freight trucks (>10,000 lbs gross vehicle weight), buses, freight
and passenger aircraft, freight and passenger rail, freight shipping,
and miscellaneous transport such as recreational boating. Light-duty vehicle
fuel consumption is further subdivided into personal usage and commercial
fleet consumption.
Key Assumptions
Light-Duty Vehicle Assumptions
The light-duty vehicle Manufacturers Technology Choice Model (MTCM) includes
63 fuel saving technologies with data specific to cars and light trucks
(Tables 7.1 and 7.2) including incremental fuel economy improvement,
incremental cost, first year of introduction, and fractional horsepower
change.
The vehicle sales share module holds the share of vehicle sales by manufacturers
constant within a vehicle size class at 2007 levels based on National
Highway Traffic and Safety Administration data. [1] EPA size class sales
shares are projected as a function of income per capita, fuel prices, and
average predicted vehicle prices based on endogenous calculations within
the MTCM. [2]
The MTCM utiizes 63 new technologies for each size class and manufacturer
based on the cost-effectiveness of each technology and an initial availability
year. The discounted stream of fuel savings is compared to the marginal
cost of each technology. The fuel economy module assumes the following:
- The economic effectiveness of all fuel technologies are evaluated on the
basis of a 3-year payback
period using a real discount rate of 15 percent.
- Fuel economy standards reflect current law through model year 2011. For
model years 2012 through
2016, fuel econony standards reflect NHTSA and
EPA's proposed standards. For model years 2017
through 2020, the standards
reflect EIA assumed increases that ensure a light vehicle combined fuel
economy of 35 mpg is achieved by model 2020. For model years 2021 though
2030, fuel economy
standards are held constant at model year 2020 levels
with fuel economy improvements still possible
based on an economic cost
benefit analysis only.
- Expected future fuel prices are calculated based on an extrapolation of
the growth rate between a five
year moving average of fuel price 3 years
and 4 years prior to the present year. This assumption is
founded upon
an assumed lead time of 3 to 4 years to significantly modify the vehicles
offered by a
manufacturer.
Degradation factors are used to convert new vehicle tested fuel economy
values to "on-road" fuel economy values (Table 7.3). The degradation factors
represent adjustments made to tested fuel economy values to account for
the difference experienced between fuel economy performance realized in
the CAFE test procedure compared fuel economy realized under normal driving
conditions.
Commercial Light Duty Fleet Assumptions
The Transportation Demand Module is designed to divide commercial light-duty
fleets into three types: business, government, and utility. Based on this
classification, commercial light-duty fleet vehicles vary in survival rates
and duration in fleet use before being sold for use as personal vehicles
(Table 7.4). The average length of time vehicles are kept before being
sold for personal use is 4 years for business use, 5 years for government
use, and 6 years for utility use. Of total automobile sales to fleets,
80.6 percent are used in business fleets, 6.5 percent in government fleets,
and 12.9 percent in utility fleets. Of total light truck sales to fleets,
59.5 percent are used in business fleets, 3.6 percent in government fleets,
and 36.8 percent in utility fleets. [3] Both the automobile and light
truck shares by fleet type are held constant from 2004 through 2035. In
2006, 18.1 percent of all automobiles sold and 18.2 percent of all light
trucks sold were for fleet use. The share of total automobile and light
truck sales to decline over the forecast period based on historic trends.
Alternative-fuel shares of fleet vehicle sales by fleet type are held constant
at year 2005 levels. Size class sales shares of vehicles are held constant
at 2005 levels (Table 7.5). [4] Individual sales shares of new vehicles
purchased by technology type are assumed to remain constant for utility,
government, and for business fleets [5] (Table 7.6).
Annual VMT per vehicle by fleet type stays constant over the forecast period
based on the Oak Ridge National Laboratory fleet data.
Fleet fuel economy for both conventional and alternative-fuel vehicles
is assumed to be the same as the personal new vehicle fuel economy and
is subdivided into six EPA size classes for cars and light trucks.
The Light Commercial Truck Model
The Light Commercial Truck Module of the NEMS Transportation Model represents
light trucks that have a 8,501 to 10,000 pound gross vehicle weight rating
(Class 2B vehicles). These vehicles are assumed to be used primarily for
commercial purposes.
The module implements a twenty-year stock model that estimates vehicle
stocks, travel, fuel economy, and energy use by vintage. Historic vehicle
sales and stock data, which constitute the baseline from which the forecast
is made, are taken from a recent Oak Ridge National Laboratory study. [6]
The distribution of vehicles by vintage, and vehicle scrappage rates are
derived from R.L. Polk company registration data. [7],[8] Vehicle travel
by vintage was constructed using vintage distribution curves and estimates
of average annual travel by vehicle. [9],[10]
The growth in light commercial truck VMT is a function of industrial output
for agriculture, mining, construction, trade, utilities, and personal travel.
These industrial groupings were chosen for their correspondence with output
measures being forecast by NEMS. The overall growth in VMT reflects a weighted
average based upon the distribution to total light commercial truck VMT
by sector. Forecasted fuel efficiencies are assumed to increase at the
same annual growth rate as conventional gasoline light-duty trucks (<8,500
pounds gross vehicle weight).
Consumer Vehicle Choice Assumptions
The Consumer Vehicle Choice Module (CVCM) utilizes a nested multinomial
logit (NMNL) model that predicts sales shares based on relevant vehicle
and fuel attributes. The nesting structure first predicts the probability
of fuel choice for multi-fuel vehicles within a technology set. The second
level nesting predicts penetration among similar technologies within a
technology set (i.e., gasoline versus diesel hybrids). The third level
choice determines market share among the different technology sets. [11]
The technology sets include:
- Conventional fuel capable (gasoline, diesel, bi-fuel and flex-fuel),
- Hybrid (gasoline and diesel),
- Plug in hybrid (10 mile all electric range and 40 mile all electric range)
- Dedicated alternative fuel (CNG, LPG, methanol, and ethanol),
- Fuel cell (gasoline, methanol, and hydrogen), and
- electric battery powered (nickel-metal hydride and lithium ion) [12]
The vehicle attributes considered in the choice algorithm include: price,
maintenance cost, battery replacement cost, range, multi-fuel capability,
home refueling capability, fuel economy, acceleration and luggage space.
With the exception of maintenance cost, battery replacement cost, and luggage
space, vehicle attributes are determined endogenously. [13] Battery costs
for plug-in hybrid electric and all-electric vehicles are based on a production
based function over several technology phase periods. The fuel attributes
used in market share estimation include availability and price. Vehicle
attributes vary by six EPA size classes for cars and light trucks and fuel
availability varies by Census division. The NMNL model coefficients were
developed to reflect purchase decisions for cars and light trucks separately.
Where applicable, CVCM fuel efficient technology attributes are calculated
relative to conventional gasoline miles per gallon. It is assumed that
many fuel efficiency improvements in conventional vehicles will be transferred
to alternative-fuel vehicles. Specific individual alternative-fuel technological
improvements are also dependent upon the CVCM technology type, cost, research
and development, and availability over time. Make and model availability
estimates are assumed according to a logistic curve based on the initial
technology introduction date and current offerings. Coefficients summarizing
consumer valuation of vehicle attributes were derived from assumed economic
valuation compared to vehicle price elasticities. Initial CVCM vehicle
stocks are set according to EIA surveys. [14] A fuel switching algorithm
based on the relative fuel prices for alternative fuels compared to gasoline
is used to determine the percentage of total VMT represented by alternative
fuels in bi-fuel and flex-fuel alcohol vehicles.
Freight Truck Assumptions
The freight truck module estimates vehicle stocks, travel, fuel efficiency,
and energy use of three size classes: light medium (Class 3), heavy medium
(Classes 4 -6), and heavy (Classes 7-8). Within the size classes, the stock
model structure is designed to cover 38 vehicle vintages and to estimate
energy use by four fuel types: diesel, gasoline, LPG, and CNG. Fuel consumption
estimates are reported regionally (by Census Division) according to the
distillate fuel shares from the State Energy Data Report [15]. The technology
input data specific to the different types of trucks including the year
of introduction, incremental fuel efficiency improvement, and capital cost
of introducing the new technologies, are shown in Table 7.7.
The freight module uses projections of dollars of industrial output to
estimate growth in freight truck travel. The industrial output is converted
to an equivalent measure of volume output using freight adjustment coefficients.
[16],[17] These freight adjustment coefficients vary by North American
Industrial Classification System (NAICS) code with the deviation diminishing
gradually over time toward parity. Freight truck load-factors (ton-miles
per truck) by NAICS code are constants formulated from historical data.
[18]
Fuel economy of new freight trucks is dependent on the market penetration
of various emission control technologies and advanced technology components.[19]
For the advanced technology components, market penetration is determined
as a function of technology type, cost effectiveness, and introduction
year. Cost effectiveness is calculated as a function of fuel price, vehicle
travel, fuel economy improvement, and incremental capital cost. Emissions
control equipment is assumed to enter the market to meet regulated emission
standards.
Heavy truck freight travel is estimated by class size and fuel type based
on matching projected freight travel demand (measured by industrial output)
to the travel supplied by the current fleet. Travel by vintage and size
class is then adjusted so that total travel meets total demand. Initial
heavy vehicle travel, by vintage and size class, is derived using Vehicle
Inventory and Use Survey (VIUS) data. [20]
Initial freight truck stocks by vintage are obtained from R. L. Polk Co.
and are distributed by fuel type using VIUS data. [21] Vehicle scrappage
rates are also estimated using R. L. Polk Co. data. [22]
Freight and Transit Rail Assumptions
The freight rail module uses the industrial output by NAICS code measured
in real 1987 dollars and converts these dollars into an adjusted volume
equivalent. Coal production from the NEMS Coal Market Module is used to
adjust coal based rail travel. Freight rail adjustment coefficients (used
to convert dollars to volume equivalents) are based on historical data
and remain constant.[23],[24] Initial freight rail efficiencies are based
on historic data taken from the Transportation Energy Databook. [25] The
distribution of rail fuel consumption by fuel type is also based on historical
data and remains constant over the projection. [26] Regional freight rail
consumption estimates are distributed according to the State Energy Data
Report. [27]
Domestic and International Shipping Assumptions
Similar to the previous sub-module, the domestic freight shipping module
uses the industrial output by NAICS code measured in real 1987 dollars
and converts these dollars into an adjusted volume equivalent.
The freight adjustment coefficients (used to convert dollars to volume
equivalents) are based on historical data. Domestic shipping efficiencies
are based on the model developed by Argonne National Laboratory. The energy
consumption in the international shipping module is a function of the total
level of imports and exports. The distribution of domestic and international
shipping fuel consumption by fuel type is based on historical data and
remains constant throughout the forecast. [28] Regional domestic shipping
consumption estimates are distributed according to the residual oil regional
shares in the State Energy Data Report. [29]
Air TravelDemand Assumptions
The air travel demand module calculates the domestic and international
ticket prices for travel as a function of fuel cost. Domestic and international
revenue passenger miles are based on historic data, [30] per capita income,
and ticket price. The revenue ton miles of air freight are based on merchandise
exports, gross domestic product, and fuel cost. [31]
Airport capacity constraints based on the FAAsAirportCapacityBenchmarkReport2004are incorporated into the air travel demand module using airport
capacity measures. [32] Airport capacity is defined by the maximum number
of flights per hour airports can routinely handle, the amount of time airports
operate at optimal capacity, and passenger load factors. Capacity expansion
is expected to be delayed due to the economic environment and fuel costs.
Aircraft Stock/EfficiencyAssumptions
The aircraft stock and efficiency module consists of a world, US and Non-US,
stock model of wide body, narrow body, and regional jets by vintage. Total
aircraft supply for a given year is based on the initial supply of aircraft
for model year 2008, new passenger sales, and the survival rate by vintage
(Table 7.8). [33] New passenger sales are a function of revenue passenger
miles and gross domestic product.
Wide and narrow body planes over 25 years of age are placed as cargo jets
according to a cargo percentage varying from 50 percent of 25 year old
planes to 100 percent of those aircraft 30 years and older. The available
seat-miles per plane, which measure the carrying capacity of the airplanes
by aircraft type, vary over time, with wide bodies remaining constant and
narrow bodies increasing. [34] The difference between seat-miles demanded
and available seat-miles represents potential newly purchased aircraft.
If demand is less than supply, then passenger aircraft is either parked
or exported, starting with twenty nine year old aircraft, at a pre-defined
rate. Aircraft continue to be parked until equilibrium is reached. If supply
is less than demand planes are either imported or unparked and brought
back into service.
Technological availability, economic viability, and efficiency characteristics
of new aircraft are assumed to grow at a fixed rate. Fuel efficiency of
new aircraft acquisitions represents an improvement over the stock efficiency
of surviving airplanes. A generic set of new technologies (Table 7.9) are
introduced in different years and with a set of improved efficiencies over
the base year (2007). Regional shares of all types of aircraft fuel use
are assumed to be constant and are consistent with the State Energy Data
Report estimate of regional jet fuel shares.
Legislation and Regulations
Energy Independence and Security Act of 2007 (EISA2007)
The EISA2007 legislation requires the development of fuel economy standards
for work trucks (8,500 lbs. to less than 10,000 lbs GVWR) and commercial
medium- and heavy-duty on-highway vehicles (10,000 lbs or more GVWR). The
new fuel economy standards require consideration of vehicle attributes
and duty requirements and can prescribe standards for different classes
of vehicles, such as buses used in urban operation or semi-trucks used
primarily in highway operation. The Act provides a minimum of 4 full model
years lead time before the new fuel economy standard is adopted and 3 full
model years after the new fuel economy standard has been established before
the fuel economy standards for work trucks can be modified. Because these
fuel economy standards are pending and NEMS does not currently model fuel
economy regulation for work trucks or commercial medium- and heavy- duty
vehicles, this aspect of the Act is not included in AEO2010.
A fuel economy credit trading program is established based on EISA2007.
Currently, CAFE credits earned by manufacturers can be banked for up to
3 years and can only be applied to the fleet (car or light truck) from
which the credit was earned. Starting in model year 2011 the credit trading
program will allow manufacturers whose automobiles exceed the minimum fuel
economy standards to earn credits that can be sold to other manufacturers
whose automobiles fail to achieve the prescribed standards. The credit
trading program is designed to ensure that the total oil savings associated
with manufacturers that exceed the prescribed standards are preserved when
credits are sold to manufacturers that fail to achieve the prescribed standards.
While the credit trading program begins in 2011, EISA2007 allows manufacturers
to apply credits earned to any of the 3 model years prior to the model
year the credits are earned, and to any of the 5 model years after the
credits are earned. The transfer of credits within a manufacturers fleet
is limited to specific maximums. For model years 2011 through 2013, the
maximum transfer is 1.0 mpg; for model years 2014 through 2017, the maximum
transfer is 1.5 mpg; and for model years 2018 and later, the maximum credit
transfer is 2.0 mpg. NEMS currently allows for sensitivity analysis of
CAFE credit banking by manufacturer fleet, but does not model the trading
of credits across manufacturers. The AEO2010 does not consider trading
of credits since this would require significant modifications to NEMS and
detailed technology cost and efficiency data by manufacturer, which is
not readily available.
The CAFE credits specified under the Alternative Motor Fuels Act (AMFA)
through 2019 are extended. Prior to passage of this Act, the CAFE credits
under AMFA were scheduled to expire after model year 2010. Currently, 1.2
mpg is the maximum CAFE credit that can be earned from selling alternative
fueled vehicles. EISA2007 extends the 1.2 mpg credit maximum through 2014
and reduces the maximum by 0.2 mpg for each following year until it is
phased out by model year 2020. NEMS does model CAFE credits earned from
alternative fuel vehicles sales.
American Recovery and Reinvestment Act o f2009 and Energy Improvement and
Extension Act of 2008
ARRA Title I, Section 1141 modified the EIEA2008 Title II, Section 205
tax credit for the purchase of new, qualified plug-in electric drive motor
vehicles. According to the legislation, a qualified plug-in electric drive
motor vehicle must draw propulsion from a traction battery with at least
4 kilowatthours of capacity and is propelled to a significant extent by
an electric motor which draws electricity from a battery that is capable
of being rechargrd from an external source of electricity.
The tax credit for the purchase of a plug-in electric vehicle is $2,500
plus, starting at a battery capacity of 5 kilowatthours, an additional
$417 per kilowatthour battery credit up to a maximum of $7,500 per vehicle.
The tax credit eligibility and phase-out are specific to an individual
vehicle manufacturer. The credits are phased out once a manufacturer's
cumulative sales maximum after December 31, 2009. The credit is reduced
to 50 percent of the total value for the first two calendar quarters of
the phase-out period and then to 25 percent for the third and fourth calendar
quarters before being phase out entirely thereafter. The credit applies
to vehicles with a gross vehicle weight rating of less than 14,000 pounds.
ARRA also allows a tax credit of 10 percent against the cost of a qualified
elevctric vehicle with a battery capacity of at least 4 kilowatthours subject
to the same phase out rules as above. The tax credits for qualified plug-in
electric drive motor vehicles and electric vehicles are included in AEO2010.
Energy Policy Act of 1992 (EPACT)
Fleet alternative-fuel vehicle sales necessary to meet the EPACT regulations
are derived based on the mandates as they currently stand and the Commercial
Fleet Vehicle Module calculations. Total projected AFV sales are divided
into fleets by government, business, and fuel providers (Table 7.10).
Because the commercial fleet model operates on three fleet type representations
(business, government, and utility), the federal and state mandates are
weighted by fleet vehicle stocks to create a composite mandate for both.
The same combining methodology is used to create a composite mandate for
electric utilities and fuel providers based on fleet vehicle stocks. [35]
Low Emission Vehicle Program (LEVP)
The LEVP was originally passed into legislation in 1990 in the
State of California. It began as the implementation of a voluntary
opt-in pilot program under the purview of Clean Air Act Amendments of 1990
(CAAA90), which included a provision that other States could opt in to
the California program to achieve lower emissions levels than would otherwise
be achieved through CAAA90. 14 states have elected to adopt the California
LEVP.
The LEVP is an emissions-based policy, setting sales mandates for 6 categories
of low-emission vehicles: low-emission vehicles (LEVs), ultra-low-emission
vehicles (ULEVs), super-ultra low emission vehicles (SULEVs), partial
zero-emission vehicles (PZEVs), advanced technology partial zero emission
vehicles (AT-PZEVs), and zero-emission vehicles (ZEVs). The LEVP requires
that in 2005 10 percent of a manufacturers sales are ZEVs or equivalent
ZEV earned credits, increasing to 11 percent in 2009, 12 percent in 2012,
14 percent in 2015, and 16 percent in 2018 where it remains constant thereafter.
In August 2004, CARB enacted further amendments to the LEVP that place
a greater emphasis on emissions reductions from PZEVs and AT-PZEVs and
requires that manufacturers produce a minimum number of fuel cell and electric
vehicles. In addition, manufacturers are allowed to adopt alternative
compliance requirements for ZEV sales that are based on cumulative fuel
cell vehicle sales targets for vehicles sold in all States participating
in Californias LEVP. Under the alternative compliance requirements, ZEV
credits can also be earned by selling battery electric vehicles. Currently,
all manufacturers have opted to adhere to the alternative compliance requirements.
The mandate still includes phase-in multipliers for pure ZEVs and allows
20 percent of the sales requirement to be met with AT-PZEVs and 60 percent
of the requirement to be met with PZEVs. AT-PZEVs and PZEVs are allowed
0.2 credits per vehicle. EIA assumes that credit allowances for PZEVs
will be met with conventional vehicle technology, hybrid vehicles will
be sold to meet the AT-PZEV allowances, and that hydrogen fuel cell vehicles
will be sold to meet the pure ZEV requirements under the alternative compliance
path.
Transportation Alternative Cases
High Technology Case
In the high technology and low technology cases for cars and light trucks,
the conventional fuel saving technology characteristics are based on NHTSA
and EPA values.[36] Tables 7.10, 7.11, 7.12, 7.13, and 7.14 summarize
the High and Low Technology matrices for cars and light trucks. Tables
7.15 and 7.16 reflect the high and low technology case assumptions for
heavy trucks. These reflect optimistic and pessimistic values, with respect
to efficiency improvement and capital cost, for advanced engine and emission
control technologies as reported by ANL. [37]
For the Air Module, the high technology case reflects earlier introduction
years for the new aircraft technologies and a greater penetration share.
The low technology case is reflected by a delay in the introduction of
new aircraft technologies. Tables 7.17 and 7.18 reflect these cases.
Transportation Tables
Transportation Demand Module Notes |