World Energy Projection System Plus Model Documentation: Transportation Module
January 23, 2018
Introduction
Purpose of this report
The Transportation Sector Model (generally referred to as the International Transportation Energy
Demand Determinants model, or ITEDD) of the World Energy Projection System Plus (WEPS+) is a
computer-based energy demand modeling system of the world transportation sector at a regional level.
This report describes the version of ITEDD that was used to produce the transportation sector
projections published in the International Energy Outlook 2017 (IEO2017). ITEDD is one of many
components of the WEPS+ energy modeling system, but ITEDD can also be run as a separate, individual
model. The WEPS+ is a modular system, consisting of a number of separate energy models that are
joined together through the overall system model in order to communicate and work with each other.
These models are each developed independently but are designed with well-defined protocols for
system communication and interactivity. The WEPS+ modeling system uses a common and shared
database (the “restart file”) that allows all the models to communicate with each other when they are
run in sequence over a number of iterations. The overall WEPS+ uses an iterative solution technique
that allows for convergence of consumption and price to a simultaneous equilibrium solution.
This report documents the objectives, analytical approach, and development of ITEDD. It also catalogues and describes critical assumptions, computational methodology, parameter estimation techniques, and model source code. This document serves three purposes. First, it is a reference document providing a detailed description for model analysts, users, and the public. Second, it meets the legal requirement of the U.S. Energy Information Administration (EIA) to provide adequate documentation in support of its models (Public Law 93-275, section 57.b.1). Third, it facilitates continuity in model development by providing documentation from which energy analysts can undertake and analyze their own model enhancements, data updates, and parameter refinements for future projects.
Model summary
The WEPS+ ITEDD for the IEO2017 projects the amount of energy that is consumed in providing passenger and freight transportation services. This projection includes personal household on-road transportation in light-duty vehicles, which is projected by ITEDD rather than by the residential consumption model. This also includes fuel consumed by natural gas pipelines and small amounts of lubricants and waxes. The model projects transportation consumption for 10 energy sources in each of the 16 WEPS+ regions to the year 2040. Underlying the consumption projections are projections of energy service demand and energy efficiency by travel mode. Service demand is measured in passengermiles for passenger services and in ton-miles for freight services. The energy efficiency is measured as the passenger-kilometers per Btu (British thermal unit, a measure of energy consumption) for passenger services except for light-duty vehicles, where miles per gallon (MPG) is used. Efficiencies are reported in ton-miles per Btu for freight services.
ITEDD categorizes transportation services for passengers and freight in four modes: road, rail, water, and air. These modes are also disaggregated into submodes (Table 1. Transportation Submodes Included in the ITEDD Model ). ITEDD projects service demand by fuel and service based on multiple demand determinants. Service demand fuel shares are projected for most modes. The service energy efficiency projections by service and fuel are endogenous to the model. Total consumption by fuel and service is a function of demand and efficiency.
TEDD obtains macroeconomic and price projections from the WEPS+ “restart file.” These projections have been previously calculated in the WEPS+ macroeconomic model and by various transformation and supply models. The transportation model projects transportation energy consumption for a variety of energy sources and outputs them to the restart file for use by the other models.
Model archival citation
This documentation refers to the WEPS+ ITEDD as archived for IEO2017.