Seabirds in 3D: A Framework to Evaluate Collision Vulnerability With Future Offshore Wind Developments

California aims to decarbonize electricity delivered to customers in the state, with a goal ensuring that 100 percent of electricity sales are from renewable sources and zero-carbon resources by 2045. Offshore wind is expected to play an important role in reaching this goal, due to the strong and reliable winds offshore California. Realizing the potential of offshore wind while minimizing impacts to biodiversity is also a priority for the state and many stakeholders. This study evaluates the potential tradeoffs between the collision vulnerability of 44 types of seabirds and offshore wind power-generation along California's coast. Using a multi-objective framework, the team assessed anticipated energy production and seabird densities at heights where seabirds are vulnerable to colliding with rotating turbine blades, highlighting regions that minimize seabird exposure while ensuring viable power generation. Long-term datasets suggest only about 8 percent of the seabird community is likely to be present at heights exceeding 10 meters above the sea surface, a height that serves as a conservative proxy for rotor swept heights. Furthermore, seabird populations are most dense nearshore and to the south, while the best wind resources are generally offshore and to the north. These findings can guide offshore wind site selection to ensure that California's renewable energy development considers seabird populations, focusing on those that are most likely to be exposed. Actual collisions are expected at a much lower rate than exposure because of species-specific behavior that could not be accounted for in this study.