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 - and two data management systems.


Data and assumptions are fed into data handling systems that provide input to the model generators. The model generators work in the GAMS environment and produce text output that is read by the results handling system. The results handling system produces numerical and graphical (mainly via Excel) output for the user.

Choosing a data handling system:
The two systems are based on very different philosophies and have their own strengths and weaknesses in terms of the learning curve and power/flexibility. Users are encouraged to try fully functional evaluation versions of the systems before making the final decision. See the developers websites for more information:

Choosing a results handling system:
VEDA-BE works with output in its elemental form and gives the user full flexibiltiy in exploring the model solution. Elaborate tools are available for interactive and batch mode operation. It works well with both model generators.
ANSWER has comprehensive but pre-defined output tables for MARKAL models. VEDA-BE is recommended for handling results from TIMES models running under ANSWER.
See the developer's websites for more information.

Choosing a model generator:
TIMES is the successor of MARKAL. The ETSAP executive committee has decided to promote TIMES for new users starting winter 2008. However, MARKAL code will continue to be supported in its current form and it is still an option for new users who may have their own reasons to choose it over TIMES. See a comparison of the two model generators.

ETSAP tools enable one to do the kind of analysis that is summarized in this picture.

Typical Results From MARKAL/TIMES

  • 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 (MARKAL or TIMES, see 2.) For example, instances of global models include the Energy Technology Perspectives (ETP) project MARKAL model of the IEA, the TIAM model, and the European Fusion Development Agreement TIMES model. Pan-European TIMES (PET/M) is a regional model covering EU27 + Noway, 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 (perhaps consisting of a number of regional models) and is "owned" by the developer(s).
  • A "shell" is a user interface which 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). "Shells" include MUSS, developed by DecisionWare Inc. for early MARKAL models; ANSWER originally developed by ABARE and subsequently the property of Noble-Soft Systems Pty Ltd for all MARKAL variants and TIMES; and VEDA developed by KanORS Consultants for both TIMES and MARKAL. The "shells" 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 MARKAL and TIMES Model Generators are the source codes, which process each set of data files (the model, see 1.) 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 Generators also post-process the optimization results. MARKAL and TIMES result from the contributions of the Contracting Parties and the ingenuity of the developers. The source code for either model generator is available free of charge, upon providing a signed copy of the ETSAP Letter of Agreement to the ETSAP Operating Agent (currently ASATREM srl).
  • 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 for a particular instance of the MARKAL or TIMES model. Information on solvers may be found at

GAMS, appropriate solver(s) and a "shell", referred to as Third Party Software, have to be purchased by those looking to effectively use MARKAL or 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 other countries, including developing countries and those with economies in transition as well as the industrialized countries. As a result of numerous successful training and capacity building programs, today over 150 teams in more than 50 countries around the world make use of the MARKAL-MACRO family of Energy/Economy/Environment/Engineering (4E) models.

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.