Simplified analysis of balancing challenges in sustainable and smart energy systems with 100% renewable power supply

In a power system, the basic physical law states that the total production is always exactly the same as total consumption. This physical law is always fulfilled no matter the type of power plants in the power system. In a power system with large shares of solar and wind power, this means that the other power plants have to fill the gap between actual solar plus wind power and the demand during each second/minute/hour. However, if there are large amounts of solar and wind power, then sometimes the available power from solar and wind exceeds the demand. In a future system based on large shares of solar and wind power, all these different situations have to be handled, and the question is how to analyze this. Three different methods concerning how to analyze systems with large shares of solar and wind power will be presented. The methods are applied to a Swedish case with close to 100% renewable power based on hydro, solar, wind and, bio‐fuelled combined heat and power (CHP). This study shows that there are limited balancing costs for this case. The costs for curtailment of surplus as well as to keep enough capacity to cover a high load combined with low solar and low wind is comparatively small, below 0.3 Eurocent/ kWh . However, more detailed studies are needed to quantify the exact cost under different conditions, but this study indicates the size of the challenges. WIREs Energy Environ 2016, 5:401–412. doi: 10.1002/wene.194 This article is categorized under: Energy Infrastructure > Systems and Infrastructure Energy Policy and Planning > Systems and Infrastructure Energy and Development > Systems and Infrastructure