BEYOND-THE-HORIZON - RECENT DIRECTIONS IN LONG-TERM ENERGY MODELING

Extending time horizons for energy analysis increases both the cumulat ive effect of gradual structural changes and the likelihood of revolut ionary innovations, on scales ranging from individual end-use sectors or regions to the entire global economy. Distinguishing features of lo ng-term modeling therefore include technological change (e.g., new tec hnologies or factor substitution), shifts in energy supply (due to exh austion of conventional sources or the emergence of new sources), and dynamic energy-economy interactions (the impact of growth on energy de mand and simultaneous role of the energy sector in determining growth paths). A taxonomy of model types including computable general equilib rium (CGE), aggregate optimization, and energy-sector models can be de fined based on their scope of coverage (partial vs general equilibrium ) and behavioral outlook (simulation vs optimization). This paper iden tifies the motivation and key attributes of each model type with refer ence to several particular specifications.