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Generation expansion model

GEM is the Electricity Commission's generation expansion model. It was constructed in late 2006 to support the production of generation capacity expansion paths under various future scenarios; a central aspect of the grid planning assumptions, which the Commission is required to publish. The Commission is also using GEM to support a number of other workstreams and believes that some industry participants and/or their consultants may find it helpful.

GEM is a mathematical programming (i.e. optimisation) problem of the mixed integer program (MIP) type. It is coded using the GAMS software and is solved with the CPLEX solver (although alternative MIP/LP solvers could be used, e.g. XPRESS).

Matlab scripts are included for processing GEM output files and generating various plots. In addition, compiled versions of the Matlab scripts have been included for users who don't have Matlab installed on their computers. However, in order to use the compiled Matlab scripts, it is necessary to download and install the Matlab Component Runtime (MCR) exe [122676 KB].

We recommend obtaining the MCR from here to ensure compatibilty with the compiled Matlab scripts. In the interest of transparency and openness the Commission is pleased to make the GEM programs and data files freely available. It is distributed under the terms of the GNU General Public License. This means it may be freely used, modified and distributed. However, the GEM software carries no warranty, either expressed or implied, and the Electricity Commission can not be held liable for losses arising from any decisions based entirely or in part on GEM results. The GNU General Public License does not apply to the GAMS, CPLEX or Matlab software. Users are expected to purchase their own licenses for the software required to operate GEM. The Electricity Commission has negotiated an arrangement with the GAMS Development Corporation (www.gams.com) whereby the necessary licenses to solve GEM can be purchased at a substantial discount to the usual cost of a complete GAMS system. Please contact gem@electricitycommission.govt.nz for further information.

    GEM is undergoing continual development. Updates will periodically be posted on the Commission's website. Included in the release package(GEM-1-5-1.zip [4519 KB]) is a short list of planned developments. Comprehensive documentation is currently being prepared and should be available soon. The Commission invites interested parties to offer comments or suggestions on improvements to GEM. Please direct all correspondence to gem@electricitycommission.govt.nz.
    Last update on 25 August 2008 12:07 PM