Techno-economic optimization of a multimodal energy system for a fully renewable energy-supplied Danish island

Accelerating the green energy transition is of great importance in fighting global climate change. Currently, the Danish island Aero utilizes a large amount of fossil fuel-based energy resources in the electricity, heating, and transport sectors. In line with the holistic green transition initiatives in Denmark and the holistic goal of the fossil-fuel free Danish energy sector by 2050, this study aims to find a feasible solution for the island to be fully sustainable relying solely on renewable energy sources, operating in island mode. To that end, different approaches are investigated including the electrification of the transport sector, installing energy storage systems, increasing renewable energy production capacities, energy production planning, and demand side management. Using linear programming, a hybrid scenario combining these energy approaches is developed and an hourly optimization is conducted to balance the island’s energy production and demand. The proposed hybrid scenario is compared to the island’s current energy system operation (base scenario) via a techno-economic approach, where dimensioning of the technologies is evaluated and the overall system cost is projected. The results showed that the hybrid scenario achieves higher renewable energy contribution (100%) and lower system cost (1625.9 DKK/month/person) compared to that of the base scenario (55.77% and 1689.6 DKK/month/person respectively). In connection to the hybrid scenario, a sensitivity analysis is carried out to investigate the impact of specific modifications to the hybrid scenario on the system’s technical and economic performance. The results showed that installing an additional ferry is the most beneficial approach to improve the hybrid scenario’s performance.