Characterizing Air Quality Impacts Related to North Atlantic Offshore Emissions Sources

Wind energy projects are being planned and constructed off the northern Atlantic coast to provide additional energy capacity to the eastern U.S. Emissions related to construction, operation, and routine maintenance of these offshore wind projects and the chemical transformation of these emissions in the atmosphere can result in pollutants that have known negative human health effects. However, the increased electrical capacity provided by these offshore wind projects could result in some reduction to onshore electrical generating (EGU) facilities. Here, multiple air quality models (a reduced complexity tool and a more sophisticated photochemical grid model) were applied to predict annual average PM_2.5 and seasonal average maximum daily 8-hr average O₃ impacts from offshore wind projects and resulting reductions in onshore EGUs. The reduced complexity tool reasonably replicated the magnitudes and spatial gradients of impacts predicted by the photochemical transport model. Air pollution impacts from the offshore wind energy projects tended to be highest nearest the projects. Air pollution impacts were much higher from the construction phase compared to post-construction (operation and maintenance). Predicted reductions to onshore EGUs due to increased offshore energy capacity resulted in regional decreases in PM_2.5 and O₃ that outpaced increases related to offshore wind projects. This effect was more pronounced for population influenced PM_2.5 compared to O₃. This is likely due to offshore wind energy capacity being highest in the winter which results in more onshore EGU emissions reductions outside of the summer season when precursor emissions would be most impactful on O₃ production. Reductions in onshore EGU emissions were based on assumptions that the increased energy capacity would not simply meet increased demand over present-day levels or be balanced by non-fossil fuel-based energy sources such as nuclear, solar, or onshore wind farms.