Support schemes adapting district energy combined heat and power for the role as a flexibility provider in renewable energy systems

Combined heat and power units connected to district energy plants have an important role displacing condensing mode power generation and boiler-based heat-only generation. However, often the earnings on the electricity markets are not sufficient to promote the establishment of these; therefore, support schemes are needed. When designing a support scheme to promote combined heat and Power, it is important to consider that in the transition to a renewable energy system, the role changes radically from displacing traditional generation to assisting in the integration of fluctuating renewables and finally providing the electrical capacity needed during hours with insufficient wind and sun. An energyPRO-based comparison of a premium and a triple tariff support scheme is presented. The comparison shows that, during a 20-year period, the cost to society is less than half when using the triple tariff compared to using the premium scheme for providing a certain capacity. While this capacity displaces the same amount of production from condensing mode power plants, the triple tariff promotes larger thermal energy storage capacity compared to the premium scheme, which is beneficial for district energy combined heat and power to fulfil its subsequent tasks in a renewable energy system.