Energy modelling for technology assessment: the MARKAL approach

The primary objective of energy policy in many countries is to change the structure of their energy systems so as to reduce the dependence on imported oil. A large amount of funds is spent on energy research and development. The technologies competing for such funds have widely varying characteristics. These relate to costs and benefits, technical performance, environmental effects, the requirements for land, water and materials and the impact on employment. It is necessary to analyse these effects in some detail before decisions on technology programmes can be made. A complete assessment of the possible value of a particular technology cannot be made on an individual basis. It is necessary to consider many technologies simultaneously, competing against each other for various shares of the energy market. However, analysing the behaviour of the entire energy system requires the handling of an extensive amount of data and can only be done effectively with the help of a computerised system. The model, MARKAL, described in this paper is a multi-period linear programming model which has been developed and applied by 15 OECD countries for the purpose of energy technology research and development planning. Examples of the use of the model for this purpose are given both for the group as a whole and for individual countries. The model is structured so that an exogenously specified set of end-use demands must be satisfied given available technologies and energy supplies. The model allows for substitution possibilities in both the energy supply and demand sectors. A feature of the model is the use of varying objective functions such as minimum discounted costs, oil imports, or environmental effluents. These can be used individually or in combination in trade-off situations. The broader question of the use of energy modelling for technology assessment, including its limitations, is also discussed with particular reference to the insights that can be gained from the MARKAL model. Information from the MARKAL model has been used by the International Energy Agency to assist it in formulating a strategy for energy research development and demonstration.