ABSTRACT
In this work, the influence of oil-price-dependent macroeconomic variables/parameters on subsidies for promoting renewable energy supply (RES) is examined. The model used for estimating optimal subsidy, Iopt by means of break-even-point analysis for the State, contains, interalia, as independent/explanatory macroeconomic variables, the rate of interest and the rate of return on the second best, as they are influenced by the oil-price change i.e. although considered at first instance as independent they become dependent on an exogenous magnitude that varied over time. Consequently, the I opt-model becomes dynamic and the impact on the estimated values is dramatic for relatively medium/high rates of oil-price increase per period: the ranges for acceptable I opt-values (‘windows of applicability’), according to national legislation and the EU directives, turn to be very narrow and interval analysis (adopted herein to count for uncertainty) gives irrational estimates in several combinatorial spaces. Some theoretical issues are also discussed by means of trade-off diagrams, which indicate a shifting of I opt-value towards high values, a tendency expected to continue over time in the near future, provided that the oil price remains at high level.
