IEA-ETSAP Energy Systems Analysis Tools

The elegance and power of IEA-ETSAP tools enables the management of large data sets efficiently, which is the hallmark of the IEA-ETSAP methodology. There are tools that help you prepare the data to be provided to the model generator. The model generator is capable of detailed and credible representation of the energy-environment systems. The model generated is then solved using solvers to get the results. There are intuitive results visualization tools available to interpret these results – to extract insights out of information.


ETSAP developed and coded two model generators - MARKAL and TIMES. TIMES is the successor to MARKAL, and all modelers are advised to use TIMES. The MARKAL code will continue to be supported in its current form but no further development will take place.

ETSAP Tools (Previous image)

Model generator
TIMES is the state of the art model currently being developed and maintained by ETSAP. For historical reasons we offer a comparison between TIMES and MARKAL model generators.

Originally there were two user interfaces for the model generators, namely ANSWER and VEDA. Starting from 2018 no further changes are made to ANSWER, and any new user wishing to work with TIMES is encouraged to consider using the VEDA 2.0 software.

In order to create a model, data and assumptions are fed into the interface that provides input to the model generators. The model generators work in the GAMS environment and produce output that is read by the interface to produce numerical and graphical output for the user.

Users are encouraged to try fully functional evaluation versions of the user interface and GAMS. See the developer's websites for more information:

TIMES is a partial equilibrium model which enables one to do the kind of analysis that is summarized in the picture below.

Typical Results From MARKAL/TIMES

The following terms are used for the ETSAP tools:

  • The model is a set of data files (spreadsheets, databases, simple ASCII files), which fully describes the underlying energy system (technologies, commodities, resources and demands for energy services) in a format compatible with the associated model generator (TIMES). For example, instances of global models include the Energy Technology Perspectives (ETP) model of the IEA, the TIAM model, and the European Fusion Development Agreement TIMES model. Pan-European TIMES is a regional model covering EU27 + Norway, Switzerland and Iceland. Finally, there are several national models of the ETSAP partner institutions, and various regional and municipal models developed by other institutions. Each set of files defines one model and is owned by the developer(s).
  • The user interface oversees all aspects of working with a model including management of the input data, running of the Model Generator, and examining the results. It thereby makes practical the use of robust models (theoretically simple models can be handled by means of ASCII file editors, if desired). The interfaces are ANSWER originally developed by ABARE and subsequently the property of Noble-Soft Systems Pty Ltd and VEDA developed by KanORS Consultants. The interfaces were partly developed using ETSAP resources, and as such small group licenses (5 personal computers (PC)) for each are provided on request free of charge to ETSAP contracting parties and their designated representatives.
  • The TIMES Model Generator is the source code, which process each set of data files and generate a matrix with all the coefficients that specify the economic equilibrium model of the energy system as a mathematical programming problem. The Model Generator also post-process the optimization results. The source code for the TIMES model generator is written in GAMS and is available free of charge under a GPL v3.0 license.
  • General Algebraic Modeling System (GAMS) is the computer programming language in which the MARKAL and TIMES Model Generators are written. GAMS is the property of GAMS Development Corporation, Washington D.C. Information on GAMS may be found at More specific GAMS - ETSAP information can be obtained from This email address is being protected from spambots. You need JavaScript enabled to view it..
  • A solver is a software package integrated with GAMS which solves the mathematical programming problem produced by the Model Generator. Information on solvers may be found at

GAMS, appropriate solver(s) and an interface, referred to as Third Party Software, have to be purchased by those looking to effectively use TIMES at the prices established by the developers. Collectively the Model Generator(s) and Third Party Software are referred to as ETSAP Tools.

Through bilateral and multilateral partnerships, the methodologies and tools developed and used by the ETSAP network are utilized in an increasing number of countries, including developing countries and those with economies in transition as well as the industrialized countries.

Limited support is available at This email address is being protected from spambots. You need JavaScript enabled to view it.. Non-ETSAP institutions who are interested in receiving more substantial support for the development of models based on the ETSAP model generators may request ETSAP Support for the payment of an annual fee.