Exploring Near-Optimal Solutions of Energy-System Models to Increase Energy-System Resilience

In conventional energy system planning, cost optimisation is usually the decisive factor. The objective of the research, on which this article is based, is to develop alternatives to cost-optimised energy supply concepts that are near optimal cost and also meet the criterion of increased resilience. The methodology presented here thus expands the solution space for the planning of energy systems and the consideration of additional criteria beyond pure cost optimisation. The transition from a fossil fuel-based energy system to one reliant on renewable sources brings significant structural changes and uncertainties. Resilience management offers a guiding concept to address the non-linear complexities and unpredictability of this transformation process and to cope with uncertain and unknown stressors. Thus, a comparative assessment of the resilience of different future energy concepts is crucial to provide a basis for decision making and implementation of resilient energy systems. This research approach entailed the optimisation of a heat supply concept for an urban district and the investigation of near-optimal alternatives in the vicinity of the optimal solution. The resilience of these near-optimal solutions was then analysed. For this purpose, certain resilience-enhancing structures and functionalities (diversity, redundancy, buffer capacity) were evaluated by quantifiable indicators. The analysis of the heat supply scenarios has shown that resilience, measured by the indicators used, could be increased at a low additional cost. In the top-performing alternative-heat-supply scenarios generated, the diversity has been increased by 585 %, redundancy by 18 % and buffer capacity by 98 %. The majority of the generated alternatives that were examined showed that an increase in diversity and redundancy could be achieved at a relatively low additional cost.