Co-located offshore renewable energy systems: Complementarity analysis and Atlantic–Mediterranean case studies

Renewable energy systems are becoming vital in fulfilling global energy demand. In this context offshore renewable energy resources constitute an important sector in which to invest to reach the ambitious decarbonisation targets. As renewable energy sources, they are affected by weather and climate, resulting in significant spatial and temporal fluctuations hence complicating power grid stabilisation. Offshore renewable energy sources, whenever available, offer significant potential to enhance the reliability of renewable energy systems by complementing each other across temporal and spatial scales. Specifically, the integration of co-located systems within a single power station presents a viable approach to manage the natural variability of renewable energy sources. This solution relies on the complementary characteristics of renewable energy sources i.e. when one resource is lacking, another can offset this shortfall simultaneously. Indeed, complementarity analysis is becoming an effective method for evaluating an optimal combination of variable energy sources in a specific location and it can act as a decision support for new investments. Co-located energy systems that exploit highly complementary renewable resources may improve power output stability, reduce periods of energy generation shortfall, and lessen the dependency on energy storage solutions. In this project innovative complementarity metrics—including total variation, variance, and standard deviation— are used to evaluate the temporal interactions among wave, tidal, wind, and solar resources. A comparative analysis between the Mediterranean Sea conditions surrounding the Italian peninsula and the Atlantic Ocean on west coast and Irish Sea on the east coast conditions of Island of Ireland reveals significant differences in the potential of offshore renewable energy sources. The temporal complementarity results illustrate the clear benefits of varying the resource mix, with the maximum complementarity attained by mixing all four resources in Irish conditions and wind-wave-tidal in Italian conditions. Furthermore, a novel metric is devised to assess the co-located installation potential of renewable systems in a generic area under consideration, and it is applied to both Italian and Irish sea conditions. This novel metric allows for the evaluation of potential complementarity resulting from the exploitation of both a single resource and multiple combinations of co-located resources within a specific area, simplifying the selection of the most beneficial site for devices installation within the same area. In the same areas, Montecarlo analysis is undertaken with varying numbers of devices for each offshore energy resource, with each configuration reflecting a specific layout of devices in the area under consideration. This research has identified the most complementarity sites, showing that Carnsore Point and Inishtrahull Sound are the Irish locations with better conditions for the selected type of devices when all resources are combined. Finally, the ideal number of devices to be deployed in a specified region to maximise temporal complementarity while maintaining the required connecting cable length within a specific range has been computed.