World Energy Projection System Plus Model Documentation: Greenhouse Gases Module
September 29, 2011
Introduction
Purpose of This Report
The Greenhouse Gases (GHG) Model of the World Energy Projection System Plus (WEPS+) is a computer-based model that computes energy-related carbon dioxide emissions by fossil fuel energy source and to allow the user to implement various carbon policy cases (specifically carbon tax and carbon cap policies). This report describes the version of the GHG Model that was used in production of the world projections published in the International Energy Outlook 2011 (IEO2011). The GHG Model is one of 13 components of the WEPS+ modeling system. The WEPS+ is a modular system, consisting 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+ system 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 the WEPS+ GHG Model. It also catalogues and describes critical assumptions and computational methodology, 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 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 Greenhouse Gases (GHG) Model has two primary functions. First, the mode is used to calculate the energy-related carbon dioxide emissions by fuel. This is accomplished by importing all consumption by end use sector and fuel from the demand and transformation models via the restart file and applying the appropriate carbon dioxide emissions factors. A distinction between fuel used as feedstocks and “sequestered” fuels that are consumed in a carbon capture and storage (CCS) technology.
The second primary function of the GHG Model is to enable the endogenous implementation of carbon policies, such as a carbon tax or a carbon emissions cap. The model can implement a carbon tax by adding an additional price for each energy source based upon the relative carbon content. The model can also implement a carbon cap by iteratively making successively better estimates of the allowance price, which in turn causes the demand models to reduce their demand to achieve the overall emissions cap levels. The GHG Model allows the user to implement carbon taxes at a worldwide level, at a regional level, or at a combined regional and end-use sector level. Finally, the model allows the user to implement a carbon cap at a worldwide or regional level.
Model Archival Citation
This documentation refers to the WEPS+ Greenhouse Gases Model, as archived for the International Energy Outlook 2011 (IEO2011).
Model Contact
Brian Murphy
U.S. Energy Information Administration
Renewable Electricity Analysis Team
EI-81/Forrestal Building
United States Department of Energy
1000 Independence Avenue, SW
Washington, D.C. 20585
Telephone: (202) 586-1398
E-mail: Brian.Murphy@eia.gov