Deployment of wind turbines offshore along the U.S. east coast is critical to transition of the electricity supply and achieving net zero carbon emissions from the power sector by 2035. It is attractive due to the excellent wind resource and proximity to large markets. Realizing the current pipeline of 26 GW of offshore wind projects in 16 lease areas off the US east coast will almost double global offshore wind installed capacity and require capital investment of $50-120 billion. It thus requires careful management and planning. The proposed density of wind turbine installations is consistent with European offshore wind farms, but the areas are much larger raising the potential for large wake-induced power losses.
Using high-resolution simulations with the Weather Research and Forecasting (WRF) model and the modified Fitch wind farm parameterization we quantify the likelihood that current and future lease areas will operate in the wake of other lease areas, and provide information relevant to where additional offshore lease areas should and should not be located to maximum electricity production and minimized levelized cost of energy. We show that if lease areas are subject to deployment of 15 MW wind turbines with a spacing equal to the European average (1.85 km, 7.7 rotor diameters), expected electricity production is 116 TWh/year or 3% of current national supply. Wakes within and between the lease areas reduce power production by an average of one-third. Under some flow conditions mean velocity deficits of 5% can extend up to 90 km downwind of the largest lease areas. Simulations including reduced installed capacity density due to implementation of maritime corridors demonstrate power efficiency gains and may offer contingent benefits. A new metric – the normalized wake extent (NWE) – is used to describe the areal extent of disturbed flow caused by a given wind farm. It is the ratio of the spatial extent of the area with a velocity deficit of at least 5% generated by a wind farm to the area of the wind farm. Output from these detailed simulations is also used to derive engineering models of NWE as a function of wind turbine installed capacity and prevailing meteorology (freestream wind speed, turbulent kinetic energy and boundary layer depth).