THE TIMES MODEL

Getting started with TIMES modelling

The IEA-ETSAP methodology is applied since 1976 in an increasing number of countries through bilateral and multilateral partnerships, supporting energy–climate analysis in developing, transition, and industrialised economies.

TIMES is the current state-of-the-art model generator developed and maintained by ETSAP. Building and running a TIMES model requires several components, collectively referred to as ETSAP Tools.

TIMES modelling relies on the integration of :

TIMES model generator

The core source code processes input data files and produces the mathematical programming formulation of the energy system. It also post-processes optimisation results.

TIMES model database

A set of data files (spreadsheets, databases, etc.) which fully describes the underlying energy system (technologies, commodities, resources, and demands) in a format compatible with the TIMES model generator. Each database instance is tailored to specific applications.

General Algebraic Modeling System (GAMS)

The computer programming language in which the TIMES source code is written; a commercial modelling language required to run the TIMES source code.

Solver

A mathematical optimisation package integrated with GAMS to solve TIMES models. Options include linear programming (LP), mixed-integer programming (MIP), or non-linear programming (NLP) solvers.

User interface

A software environment for managing input data, executing the model, and analysing/visualizing results. While small models can be handled using text editors, most users rely on dedicated interfaces such as VEDA (current) or ANSWER (legacy).

TIMES model generator (core source code)

The TIMES model generator is the core optimisation engine of the ETSAP methodology.
Written in the GAMS language, it is available free of charge under the GNU GENERAL PUBLIC LICENSE v. 3.0 and can be downloaded directly from GitHub.

Download TIMES

ETSAP developed and coded two model generators – MARKAL and TIMES. MARKAL was first developed since 1976 in a cooperative multinational project over a period of almost two decades by the ETSAP community. TIMES is the successor to MARKAL, and all modellers are advised to use TIMES. The MARKAL code will continue to be supported in its current form but no further development will take place. See a comparison of the two model generators.

TIMES model databases

A TIMES model database contains all the input data describing an energy system — technologies, commodities, resources, and service demands — in a format compatible with the model generator.

It is important to distinguish between the structure of a model and a specific instance of its implementation. The structure reflects the fundamental modelling framework shared by all TIMES applications, while an instance represents a fully specified database built for a given jurisdiction. Because TIMES is data-driven, the effective structure of an instance will vary according to the modeller’s inputs.

Certain features are only activated if the relevant data is provided.

In practice, the structure of a TIMES instance is defined by the union of the underlying TIMES equations and the data supplied by the modeller. This combination produces the mathematical representation of the Reference Energy System (RES) for each region. TIMES is therefore described as a model generator — it creates a complete model instance from the information provided.

TIMES does not come with pre-loaded data; building the database is the modeller’s responsibility. However, some open-source model instances are available in the Resources page. These include examples such as the ETSAP TIAM global model and other models developed by partner institutions.

Third-party software

To operate TIMES effectively, external software components are required – the GAMS programming language, with the appropriate solver(s), and the VEDA user interface – and must be purchased from their respective developers at the prices they set.

Fully functional 60-days evaluation versions and purchase options for GAMS+Solver and VEDA are available here.

GAMS

GAMS is commercial software and requires a valid license. For most model applications, a linear programming (LP) solver is sufficient; more advanced features may require a mixed-integer (MIP) or non-linear (NLP) solver.

Solvers may be open source or proprietary, and must either be integrated into GAMS or callable from it. GAMS is the property of GAMS Development Corporation, Washington D.C. More specific GAMS – ETSAP information can be obtained from Gary Goldstein.

VEDA

VEDA (VErsatile Data Analyst), a proprietary software developed by KanORS-EMR (India), is the primary commercial interface for working with TIMES (and MARKAL).

It is a robust, user-friendly model management system designed to handle every stage of the modelling workflow — from organising and editing large, complex input datasets to running the TIMES code and exploring results. VEDA reads structured Excel-based inputs, passes them to the TIMES model generator in the GAMS environment, and processes the outputs into numerical and graphical formats for analysis. Optimised for large-scale, multi-region models but equally capable of supporting smaller systems, VEDA’s strength lies in improving the efficiency, transparency, and flexibility of managing data-intensive models. Under continuous development since its origins in the late 1990s, VEDA now serves licensed users in over 90 countries, supported by an active VedaForum and VedaSupport.

More specific VEDA – ETSAP information can be obtained from Dr. Amit Kanudia.

ANSWER, a proprietary software developed by Noble-Soft Systems Pty Ltd. (Australia), was one of the two main user interfaces for TIMES (and MARKAL) model generators. Known for its user-friendly design and gentle learning curve, it supports data entry and editing, model execution in the GAMS environment, and results review within an integrated Microsoft Access database, with Excel tools for bulk data handling. Dr. Ken Noble, the owner of the ANSWER software has retired at the end of 2017. Starting from 2018 no further changes are made to ANSWER and is now considered a legacy option.

Any new user wishing to work with TIMES is encouraged to consider using the VEDA 2.0 software.