In order to mitigate the impacts of climate change, the international community envisages significant investments in electricity generation from renewable energy sources (RES). The integration of this decentralized and fluctuating type electricity generation poses several challenges to planning, operation, and economics of power systems. The established energy systems were originally designed for a centralized electricity generation that follows the uncontrolled but well predictable demand. However, for large shares of RES, relying only on the flexibility of the generation side would be economically inefficient. Furthermore, the environmental benefits of using RES would be depleted by additional carbon emissions from ramping highly flexible fossil-fueled power plants. An appealing alternative to facilitate the efficient integration of large shares of RES is to exploit the so far mainly passive demand side as an additional source of flexibility. The established centralized approaches can hardly handle the fine-grained and decentralized nature of demand side flexibility. Therefore, the intermediation between centralized control and decentralized demand will play a major role in future energy markets, which constitutes the overarching topic of this dissertation.