Subsidies for renewable energy in inflexible power markets

This paper analyses how short-term operational efficiency and the CO 2 emissions of a power system depend on different subsidies for wind power and on the flexibility of the power system. This is analysed in the framework of a numerical power market model, calibrated to Danish data, where the start-up costs and other constraints in fossil-fuelled power plants are taken into account. The main conclusion is that flexibility is crucial for the costs of integrating wind power in an existing system. If thermal power plants are inflexible, subsidies for wind power should strive to increase the flexibility of the market by passing market signals to wind power. A subsidy that conceals market signals from wind power producers (a production subsidy) or disconnects wind power incentives from the market signals altogether (a fixed price) increases costs considerably. An inflexible power system should aim to introduce optimal subsidies (an investment subsidy) instead of production subsidies or a fixed price. The design of the subsidy scheme should take into account both the characteristics of the existing system and the characteristics of renewables.