Hybrid wind-solar energy resources mapping in the European Atlantic

The complementarity of offshore wind and solar resources can enhance the energy output of a hybrid farm and reduce its variability relative to a stand-alone, conventional offshore wind farm. In this work offshore wind and solar resources are characterised and mapped in a large study area covering the European Atlantic, the North and Baltic Seas, and the Canary Islands. The intra-annual and overall variabilities of wind power density and solar irradiance are investigated, and their complementarity is evaluated on the basis of their correlation. Negatively correlated regions include the seas around Ireland and Great Britain, with vast wind resources (mean wind power density ~1500 Wm-2 off W Ireland) and comparatively limited solar resources (mean solar irradiance ~100 Wm-2). Positively correlated regions include notably the Canary Islands, with the highest values of solar irradiance in the study area (mean values of ~280 Wm-2). Two study sites are chosen for more detailed investigation - one with a negative correlation, off W Ireland; the other with a positive correlation, off the Canary Islands. Even in the positively correlated regions, it is found that the correlation coefficient is never large (always under 0.2), which signals an opportunity for reducing power output variability through hybrid or co-located wind-solar farms. This, along with the other advantages of hybrid or co-located wind-solar farms (optimised use of scarce marine space, shared electrical infrastructure, shared O&M crews and vessels, etc.), attests to their potential in the European Atlantic. This potential could be realised through new hybrid or co-located wind-solar farms, or by retrofitting floating solar PV into existing offshore wind farms.

The energy park of the future: Modelling the combination of wave-, wind- and solar energy in offshore multi-source parks

To mitigate the effects of climate change, a significant percentage of future energy generation is set to come from renewable energy sources. This has led to a substantial increase of installed offshore wind in the North Sea in the last years (28 GW in 2021) and is projected to further accelerate to an installed capacity of 212 GW by 2050. Increasing the renewable energy grid penetration brings challenges, including 1) limitations in space availability and 2) the reliability of renewable energy systems in terms of grid balancing. In the North Sea, maritime space is getting scarce and the projected upscaling of offshore wind is putting pressure on the chemical-, biological, and physical balance of the marine ecosystem. Without economically viable large-scale storage systems, a renewable energy system focused on one intermittent source does not provide reliable baseload- and energy demand compliance. By integrating different supplementary offshore renewable energy sources into multi-source parks output becomes smoother, while the energy yield per area increases. Despite multiple studies stating the benefits of multi-source energy parks of either wind and wave energy or wind and PV energy, no study has been conducted on the co-location of all three offshore renewables. This study combines and analyzes the three offshore renewable energy sources: wave-, offshore PV- and wind energy in the example of Ten Noorden van de Waddeneilanden, a future wind farm north of the Dutch Wadden Islands. The additional renewables are allocated within the wind turbine spacing, taking into account safety zones and maintenance corridors. Co-location of these renewables increases the extracted energy density by 22%, making more efficient use of the limited available marine space. Moreover, the park output becomes smoother as the yearly-averaged coefficient of variation decreases by 13%, the capacity factor with respect to the export cable increases by 19%, and the hours where the output of the park is below 20% of the export cable capacity decreases by 86.5%.

Floating solar panels on reservoirs impact phytoplankton populations: A modelling experiment

Floating solar photovoltaic (FPV) deployments are increasing globally as the switch to renewable energy intensifies, representing a considerable water surface transformation. FPV installations can potentially impact aquatic ecosystem function, either positively or negatively. However, these impacts are poorly resolved given the challenges of collecting empirical data for field or modelling experiments. In particular, there is limited evidence on the response of phytoplankton to changes in water body thermal dynamics and light climate with FPV. Given the importance of understanding phytoplankton biomass and species composition for managing ecosystem services, we use an uncertainty estimation approach to simulate the effect of FPV coverage and array siting location on a UK reservoir. FPV coverage was modified in 10% increments from a baseline with 0% coverage to 100% coverage for three different FPV array siting locations based on reservoir circulation patterns. Results showed that FPV coverage significantly impacted thermal properties, resulting in highly variable impacts on phytoplankton biomass and species composition. The impacts on phytoplankton were often dependent on array siting location as well as surface coverage. Changes to phytoplankton species composition were offset by the decrease in phytoplankton biomass associated with increasing FPV coverage. We identified that similar phytoplankton biomass reductions could be achieved with less FPV coverage by deploying the FPV array on the water body's faster-flowing area than the central or slower flowing areas. The difference in response dependent on siting location could be used to tailor phytoplankton management in water bodies. Simulation of water body-FPV interactions efficiently using an uncertainty approach is an essential tool to rapidly develop understanding and ultimately inform FPV developers and water body managers looking to minimise negative impacts and maximise co-benefits.