World Energy Projection System (WEPS): 

Overview

Independent Statistics & Analysis

www.eia.gov

U.S. Department of Energy

Washington, DC 20585

Last Updated 2023 
U.S. Energy Information Administration | World Energy Projection System: Overview i

This report was prepared by the U.S. Energy Information Administration (EIA), the statistical and 

analytical agency within the U.S. Department of Energy. By law, EIA’s data, analyses, and forecasts are 

independent of approval by any other officer or employee of the U.S. Government. The views in this 

report therefore should not be construed as representing those of the U.S. Department of Energy or 

other federal agencies.
U.S. Energy Information Administration | World Energy Projection System: Overview 1

Contents

Introduction .................................................................................................................................................. 2

Historical Data............................................................................................................................................... 4

Global Activity Module ................................................................................................................................. 4

Residential Demand Module ........................................................................................................................ 5

Commercial Demand Module....................................................................................................................... 5

Industrial Demand Module ........................................................................................................................... 5

Transportation Demand Module .................................................................................................................. 6

Electricity Module ......................................................................................................................................... 7

District Heat Module..................................................................................................................................... 7

Hydrocarbon Activity Module....................................................................................................................... 7

Coal Supply Module ...................................................................................................................................... 8

Greenhouse Gases Module........................................................................................................................... 9

Convergence Module.................................................................................................................................... 9

Table of Figures

Figure 1. World Energy Projection System (WEPS) regions.......................................................................... 3
U.S. Energy Information Administration | World Energy Projection System: Overview 2

Introduction

The World Energy Projection System (WEPS) generates projections of energy consumption, prices, and 

production for the International Energy Outlook (IEO). This overview briefly describes the methodology 

and scope of each of the component modules of WEPS and the modeling system. Further details on 

each of the component modules of WEPS are available in individual module documentation sections.

The complete WEPS system contains three main parts:

• A common database to track historical energy data and WEPS projections

• Energy modules that represent the various sector-level demand, transformation, and supply 

projection activities 

• A convergence module that determines when the system has reached an equilibrium between 

supply and demand

WEPS is a modular system that is made up of a number of separate energy modules joined through a 

common database, which enables them to communicate and work with each other. We develop each of 

these modules independently and incorporate well-defined guidelines, or protocols, for system 

communication and interactivity. The overall WEPS system uses an iterative solution technique that 

works toward converging consumption and price in an equilibrium solution.

The core WEPS modules together simulate the international energy system, along with a greenhouse gas 

emissions module. The system also includes modules that perform preprocessing and post-processing, 

including various final reporting programs.

The core set of WEPS modules, in order of execution, are:

• Global Activity Module

• Residential Demand Module

• Commercial Demand Module

• Industrial Demand Module

• Transportation Demand Module

• Electricity Module

• District Heat Module

• Hydrocarbon Activity Module

• Coal Supply Module

• Greenhouse Gas Module

• Convergence Module

Each module is run independently but reads and writes to a common database to communicate with 

other modules. The common database provides seed values for macroeconomic quantities, energy 

prices, and energy consumption. The system runs each module in turn before running the convergence

module, which determines if the system has converged. If the system has not converged, it begins 

another sequence (iteration). If it has converged, it finishes with report writing.

WEPS models the world as 16 regions.
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Figure 1. World Energy Projection System (WEPS) regions

Source: U.S. Energy Information Administration

We sometimes report WEPS results according to the following aggregate regions:

• Americas: United States, Canada, Chile, Colombia, Puerto Rico, U.S. Virgin Islands, Mexico, 

Antarctica, Antigua and Barbuda, Argentina, Aruba, The Bahamas, Barbados, Belize, Bermuda, 

Bolivia, Brazil, British Virgin Islands, Cayman Islands, Costa Rica, Cuba, Dominica, Dominican 

Republic, Ecuador, El Salvador, Falkland Islands, French Guiana, Greenland, Grenada, 

Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Jamaica, Martinique, Montserrat, 

Netherlands Antilles, Nicaragua, Panama, Paraguay, Peru, St. Kitts and Nevis, St. Lucia, St. Pierre 

and Miquelon, St. Vincent/Grenadines, Suriname, Trinidad and Tobago, Turks and Caicos Islands, 

Uruguay, Venezuela

• Europe and Eurasia: Austria, Belgium, Czech Republic, Denmark, Estonia, Finland, France, 

Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania Luxembourg, Netherlands, 

Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye, United 

Kingdom, Albania, Armenia, Azerbaijan, Belarus, Bosnia and Herzegovina, Bulgaria, Croatia, 

Cyprus, Faroe Islands, Georgia, Gibraltar, Kazakhstan, Kosovo, Macedonia, Malta, Moldova, 

Montenegro, Romania, Russia, Serbia, Tajikistan, Turkmenistan, Ukraine, Uzbekistan

• Africa and Middle East: Bahrain, Iran, Iraq, Jordan, Kuwait, Lebanon, Oman, Palestinian 

Territories, Qatar, Saudi Arabia, Syria, United Arab Emirates, Yemen, Algeria, Angola, Benin, 

Botswana, Burkina Faso, Burundi, Cameroon, Cape Verde, Central African Republic, Chad, 

Comoros, Congo (Brazzaville), Congo (Kinshasa), Côte d’Ivoire, Djibouti, Egypt, Equatorial 

Guinea, Eritrea, Eswatini, Ethiopia, Gabon, The Gambia, Ghana, Kenya, Lesotho, Liberia, Libya, 
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Madagascar, Malawi, Mali, Mauritania, Mauritius, Morocco, Mozambique, Namibia, Niger, 

Nigeria, Reunion, Rwanda, Sao Tome and Principe, Senegal, Seychelles, Sierra Leone, Somalia, 

South Africa, South Sudan, St. Helena, Sudan, Tanzania, Togo, Tunisia, Uganda, Western Sahara, 

Zambia, Zimbabwe

• Asia-Pacific: Australia, American Samoa, Guam, Japan, New Zealand, South Korea, Afghanistan, 

Bangladesh, Bhutan, Brunei, Burma (Myanmar), Cambodia (Kampuchea), China, Cook Islands, 

Fiji, French Polynesia, Hong Kong, India, Indonesia, Kiribati, Laos, Macau, Malaysia, Maldives, 

Mongolia, Nauru, Nepal, New Caledonia, Niue, Northern Mariana Islands North Korea, Pakistan, 

Papua New Guinea, Philippines, Samoa, Singapore, Solomon Islands, Sri Lanka, Taiwan, Thailand, 

Timor-Leste (East Timor), Tonga, Vanuatu, Vietnam, Wake Islands

Individual modules can use more detailed regions for internal calculations.

Historical Data

We use several key historical data sources for WEPS:

• EIA’s International Energy Statistics (IES) database 

– Provides country-level data for the following fuels consumed for electricity generation:

• Liquids

• Natural gas

• Coal

• Nuclear

• Hydroelectric and other renewables

– Includes data on electricity generation and installed generating capacity for:

• Thermal (liquid fuels, natural gas, coal)

• Nuclear

• Hydroelectric

• Other renewables, specifically wind, biomass and waste, geothermal, solar, tide,

wave, and fuel cells

• The international data produced and maintained by the International Energy Agency (IEA) in 

Paris as part of its energy balances database provide country-level consumption data for a wide 

variety of flows (sectors and users) and for a wide variety of products (detailed petroleum 

products, coal types, renewable sources, etc.). We use these detailed data to derive the 

historical, end-use sector data used in WEPS demand modules.

• Historical data and projections for the United States are from our most recent Annual Energy 

Outlook.

The EIA IES database provides the overall consumption levels for non-U.S. regions, and the IEA data 

provide consumption information at more detailed levels. The IEA data, therefore, must be calibrated 

(or shared) to agree with the EIA data.

Global Activity Module

The commercially available Oxford Economics Global Economic Module (GEM) and Global Industry 

Module (GIM) generate projections of gross domestic product (GDP) and gross output for the various 
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WEPS regions and their respective industrial sectors, given energy inputs from WEPS. The theoretical 

structure of GEM differentiates between the short-term and long-term projections for each country and

extensively covers the links between different economies. GEM produces GDP outputs for WEPS and 

provides drivers for GIM. GIM calculates gross output in various industrial sectors for each WEPS region 

based on input-output relationships.

Residential Demand Module

The WEPS Residential Demand Module projects household energy consumption with one exception—

the Transportation Demand Module projects residential demand for motor fuel.

The Residential Demand Module primarily uses a dynamic econometric equation for the key energy 

sources, basing the projection on household income, residential retail energy prices, and an assumed 

future trend. The dynamic equation uses a lagged dependent variable to approximate fuel stock 

accumulation in the calculation of fuel prices for each region over time. Income and price projections

are available from the Global Activity Module and supply modules via the common database. The trend 

factor is meant to represent continuing impacts on energy use not directly represented in household 

income and prices, and it may include the effects of a variety of behavioral, structural, and policyinduced activities.

Commercial Demand Module

The WEPS Commercial Demand Module projects energy consumption that takes place in commercial 

buildings and activities. It also includes municipal activities, such as street lighting.

The Commercial Demand Module primarily uses a dynamic econometric equation for the key energy 

sources, basing the projection on service sector gross output, prices, and an assumed future trend. The 

dynamic equation uses a lagged dependent variable to approximate fuel stock accumulation in the 

calculation of fuel prices for each region over time. Service sector gross output and price projections are 

available from the Global Activity Module and supply modules via the common database. The trend 

factor is meant to represent continuing impacts on energy use not directly represented in service sector 

gross output and prices, and it may include the effects of a variety of behavioral, structural, and policyinduced activities.

Industrial Demand Module

The WEPS Industrial Demand Module (also known as the World Industrial Module, or WIM) projects the 

amount of energy that is directly consumed as a fuel or as a feedstock by industrial processes and 

activities. This projection includes both energy-intensive and non-energy-intensive manufacturing 

industries as well as non-manufacturing industries. 

WIM uses an array of seven energy intensity (EI) modules to find the best fit for each region and 

industry sector based on historical trends, statistical measures, and analyst judgement. WIM has three 

ordinary least squares (OLS) and three least absolute difference (LAD) modules, with each type featuring 

a logarithmic growth, exponential decay, and flat module where LAD modules revert to the historical
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median and OLS modules return to the historical mean. The seventh module assumes exponential decay 

in all cases and is linked to the last historical year.

All seven EI modules use historical energy intensity data to estimate the coefficients that they apply to

compute projections for the projection period. An algorithm ranks the EI module results using several 

statistical indicators; the main indicator is the Akaike Information Criterion corrected for small samples. 

The top-ranked EI module result is selected, unless an analyst overrides the EI module selection 

algorithm. The energy consumption for each region and industry sector is calculated as the gross output 

multiplied by the projected EI. The energy consumption in each fuel category is calculated as the total 

consumption in a region-industry multiplied by the fuel shares.

We do not use the seven EI modules to calculate energy consumption from feedstocks in basic 

chemicals, other industrial, and the iron and steel industry. Feedstocks are not subject to efficiency 

improvements and have energy intensity levels frozen at the last historical year level for each region. 

Iron and steel industry projections are based on historical trends in physical production levels, 

production methods (primary versus secondary), and fuel consumption by region.

Transportation Demand Module

The WEPS Transportation Demand Module projects the amount of energy consumed to provide 

passenger and freight transportation services. This projection includes personal household on-road 

transportation in light-duty vehicles (counted here rather than in the Residential Demand Module), fuel 

consumed by natural gas pipelines, and small amounts of lubricants and waxes. The module projects

transportation consumption for 14 energy sources in each of the WEPS regions over the projection 

period. The Transportation Demand Module provides an accounting framework that considers energy 

service demand and service intensity (efficiency) for the overall stock of vehicles. The service demand is 

a measure of overall passenger miles for passenger services and overall ton miles for freight services. 

The service intensity is a measure of passenger miles per unit of energy expended (in British thermal 

units [Btu]) for passenger services and ton miles per unit of energy expended (in Btu) for freight 

services.

The Transportation Demand Module:

• Uses a bottom-up approach to estimate demand for transportation energy by mode (such as 

road, rail, air, and marine) and vehicle type (such as light-duty vehicles, freight trucks, passenger 

rail, etc.)

• Estimates transportation energy consumption by fuel and region

• Estimates vehicle stocks by vehicle type and region

The Transportation Demand Module reads macroeconomic (GDP and population) and energy price 

projections from the common database. After running, the module provides transportation energy 

consumption projections to the common database.
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Electricity Module

The WEPS Electricity Module, also called the International Electricity Market Module (IEMM), projects:

• Electricity generating capacity additions and retirements

• Electricity generation

• Electricity added to and removed from storage 

• Electricity sold and purchased

• Electricity delivered to consumers

• Fuel consumed in electricity generation

• Carbon dioxide emissions

• Electricity prices

This module projects these quantities for each of the 16 WEPS regions by year and time-slice. A timeslice is a time period specified by EIA analysts as a period of the day during a particular month or season 

(for example, January from 6:00 a.m. to 7:00 a.m.). In some cases, some of the quantities listed above 

are also broken out by other characteristics such as the type of technology used to generate the 

electricity. 

The module projects these quantities by minimizing an objective function, subject to several constraints. 

The objective function represents the total cost for electricity suppliers to meet all electricity demands, 

by year and time slice, projected by the WEPS demand modules. Examples of constraints include limits 

on fuel-specific electricity generating equipment, policy constraints (for example, renewable portfolio 

standards), and emissions caps. The IEMM uses linear programming to perform the constrained 

optimization.

District Heat Module

The WEPS District Heat Module projects the generation of district heat (steam or hot water from an 

outside source used as an energy source in a building) to satisfy the demands projected by the 

Residential Demand Module, Commercial Demand Module, and Industrial Demand Module for each 

region. For each fuel, the module estimates the amount of heat generated and the amount consumed, 

as well as the end-use price of heat for each of the three demand sectors. In addition, the module

projects fuel consumed and heat generated in each of the WEPS regions over the projection period for 

eight energy sources. The module uses prices from the supply modules for distillate, residual fuel, 

natural gas, and coal.

The District Heat Module uses a stock/flow approach in which it adds new heat generation capability 

each year as necessary, based on the heat generation requirement from the end-use demand sectors. 

The module takes into account the amount of heat that is available from combined-heat-and-power 

plants in the electric power sector.

Hydrocarbon Activity Module

The WEPS Hydrocarbon Activity Module (World Hydrocarbon Activity Module) is a linear integer 

optimization module that projects the supply of liquid fuels and natural gas necessary to meet global 
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consumption, along with imports and exports of those products. It also provides WEPS with projections 

of:

• Energy used in oil and natural gas exploration

• Energy used related to natural gas transmission

• Refining consumption

• End-use sector prices by WEPS region and commodity

Coal Supply Module

The WEPS Coal Supply Module (International Coal Market Module, or ICMM) contains three submodules 

that determine the production, import, export, and price of coal:

• Data processor

• Production module

• Logistics module

Each component is connected to the others to process data from external input files, to create and to 

shift coal supply curves, and to project the coal trade between each pair of regions. 

The data processor starts the ICMM run by creating the input files necessary to run the production 

module and the logistics module. For example, it:

• Separates coal demand data into the four (or more) coal types defined by EIA analysts

• Creates regions, defined in the ICMM, to generate transportation rates based on data about 

trade routes

At the end of each run, the data processor creates the ICMM outputs for the common WEPS database

and for a module-specific diagnostic tool. 

The production module creates the coal supply curves that the logistics module uses to project the price 

per unit of coal. Through an iterative process, the production module and the logistics module compare 

and adjust coal supply curve parameters. This process (called the supply shift) allows the modules to 

simulate regional decisions, based on the previous year’s projections, to increase or decrease their 

production in the current projection year. The frequency of the adjustments is used as a convergence 

criterion: convergence is considered met if the supply shift does not change the coal production 

projected by the logistics module. 

The logistics module projects the quantities of coal shipped from supply regions to demand regions. It 

uses a linear program (LP) that maximizes profit. It also projects the prices of different coal commodities 

(that is, metallurgical, bituminous, subbituminous, and lignite) in the demand regions, the quantities 

shipped on each trade route, and coal production quantities. The profit maximization LP determines the

trade routes with the lowest transportation rates and the supply regions with the lowest supply prices

to meet demand at the lowest possible delivered price. The logistics module passes the projected coal 

production quantities to the production module, which uses them to create new supply curves for the 

next iteration. 
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Greenhouse Gases Module

The WEPS Greenhouse Gases Module projects energy-related carbon dioxide emissions by taking energy 

consumption projections from all other WEPS modules and applying carbon dioxide emissions factors to 

each fuel by WEPS region. The emissions factors are calibrated to recent historical data from EIA’s 

International Energy Statistics database. Emissions estimates provided by the module take into account 

some limited carbon capture and storage within each region’s electric power sector. The module does 

not address carbon dioxide emissions from non-energy consumption of fossil fuels, nor does it account 

for non-carbon dioxide greenhouse gas emissions.

Convergence Module

The WEPS Convergence Module evaluates and finds an equilibrium in which selected price and 

consumption variables have not changed more than an analyst-defined tolerance between successive 

WEPS iterations. After the other WEPS modules have run, the WEPS convergence module checks 

whether an equilibrium has been found. If not, then other modules are executed again, using prices and 

quantities from the preceding iteration. As configured, the WEPS convergence module adjusts prices up 

or down to speed finding an equilibrium.