Robust Energy Systems. Strategies for CO2 Emission Control

Sammanfattning: This dissertation deals with strategies to handle uncertainty about restrictions in CO2 emissions. A method has been developed for treating sequential decisions in energy planning. The method is an extension of the conventional scenario analysis, and is based on the evaluation of decision trees. The method has been applied using a standard energy systems engineering model, IEA-MARKAL. The model is a dynamic linear programming model of the technical energy system. Three strategies have been considered: immediate action to adapt to a future CO2 emission constraint (Commitment), business-as-usual (No Hedging), and Hedging. In the Hedging strategy, measures are taken outside the energy system to enable swift implementation of new technologies if emission restrictions are imposed. However, the energy system itself is allowed to develop according to baseline assumptions up to the time when the uncertainty has been resolved. Analyses have been undertaken for the national energy system of Sweden, as well as for one regional and one local energy system. The development of the national energy system has been studied for two rates of economic growth in combination with three nuclear policies and two CO2 policies. The value of preparations for meeting a possible restriction on CO2 emissions, i.e., following either the Commitment or Hedging strategy, is considerably higher when the energy demand increases rapidly. In the low growth case, the choice of strategy is largely dependent upon the decision maker's estimate of the likelihood of an emission cap. In the high growth case, this likelihood must be considered to be very small in order to choose the No Hedging strategy, even with reinvestments in nuclear capacity beyond 2010.