Quantifying operational flexibility of distributed cross-sectoral energy systems for the integration of volatile renewable electricity generation

As one element of power system transition, distributed cross-sectoral energy systems (DCES) can provide flexibility for the electricity market. So far, no applicable method for quantifying the flexibility potential of DCES operation exists. Nonetheless, by comparing the flexibility demand of the electricity market and the electricity flow between a DCES and the electricity grid it becomes possible to quantify market-serving flexibility of DCES operation. In this work, we categorize aim and scope of already known flexibility quantification methods and develop a new method to assess DCES market-serving flexibility covering residual load (RL). Part of this method is the new developed quantification indicator Flexibility Deployment Index (FDI), integrating two factors: The RL of the electricity market and the electricity purchase and feed-in of a DCES. By normalizing both factors, operation of different DCES concepts and scenarios regarding their flexibility can be compared. The developed quantification method is applied in a case study of a hospitals' DCES in Germany. Using a MILP optimization model with different technology concepts and scenarios, we study FDI variation for a fixed tariff, a dynamic tariff and a CO<inf>2</inf>-emission-optimized operation. The results of the case study prove that high-capacity combined heat and power units combined with thermal storage units lead to high flexibility provision. Also, the results outline higher flexibility provision in the winter than in the summer period.