Available at www.world-nuclear.org/ uploadedFiles/REPORT_OptimizCapacity.pdf. The present chapter broadens and deepens the treatment of system effects. Section 4.1 provides an overview of system effects or externalities in the power sector with the help of the comprehensive system cost matrix. It will also characterise more specifically the system effects at the grid-level, such as additional investments in the grid transport infrastructure, short-term balancing and long-term backup capacity.