Summary
In reviewing public comment letters submitted during prior stages of BOEM’s planning process, including those provided by the Commonwealth of Massachusetts, Cape Cod Commission, and National Park Service, regarding viewshed impacts concerns, particularly to the Cape Cod National Seashore, BOEM produced several visual simulations to depict hypothetical offshore wind development scenarios within the Proposed Sale Notice (May 2024) lease areas. These simulations will inform BOEM on future planning and leasing efforts, including the designation of final lease areas.
How would actual offshore wind facilities differ from these visual simulations?
Based on the knowledge we have today, the simulations are designed to represent a most extreme impact scenario (e.g., operating capacity, wind turbine size, spacing, configuration, and meteorological conditions that maximize visibility) that assumes advancements in floating wind technology consistent with industry trends we have observed for fixed turbine technology.
The visual simulations illustrate theoretical wind projects using hypothetical 16-18+ MW turbines that are not commercially available for floating wind technology. Each turbine has a hub height of 725 ft, rotor diameter of 935 ft, and maximum height at the blade tip of 1,171 ft. Turbines are modeled in a grid pattern, 1 nautical mile (nm) apart, with the first row oriented on the shore-most boundary of the proposed lease areas and filling in seaward to represent the “most-visible” representation of each wind facility.
The visual simulations model a hypothetical project buildout of 1,142 16-18+ MW turbines for a total generating capacity of approximately 15 GW of renewable energy:
| Proposed Lease Area | Modeled Number of Turbines Assuming 1nm x 1nm Spacing |
| OCS-A 0562 | 143 |
| OCS-A 0563 | 154 |
| OCS-A 0564 | 129 |
| OCS-A 0565 | 139 |
| OCS-A 0566 | 154 |
| OCS-A 0567 | 142 |
| OCS-A 0568 | 149 |
| OCS-A 0569 | 132 |
| Total for All Proposed Lease Areas | 1,142 |
In addition, two sets of simulations were produced for each key observation point (KOP) that illustrate variations in wind turbine visibility. The 1st set is titled “Predicted Visibility” which approximates the visibility of the hypothetical project buildout based on the atmospheric conditions and natural lighting angles on the day and at the time the photo was taken. The wind turbines generators are difficult to see given the visibility conditions at the time of the photo.
To offset this result, a second set of simulations were produced titled “Maximum Visibility”. These simulations show the wind turbine generators as if the atmospheric conditions in the photo have no effect on their visibility. However, the natural lighting angle is accurately simulated to show how sun angle would affect visibility on the day and at the time the photo was taken (e.g., front-lit, side-lit, backlit).
These two sets of simulations were produced to help people familiar with the variations in visibility off the coast of Cape Cod to develop a more informed insight on probability of actual visibility. If the atmospheric conditions in the photo are the more common viewing condition, then the “Predicted Visibility” series may represent a more frequent and theoretical impact level. If atmospheric conditions in the photos are uncommon, then the “Maximum Visibility” series may represent the more frequent and theoretical level of impact.
Visual contrast is created by light reflecting off the surface of wind turbine generators and will vary throughout the day depending on the visual character of the horizon’s backdrop and whether the wind turbine generators are backlit, side-lit, or front-lit. Depending on sun angle, the backdrop sky color may have various intensities of white to gray and sky blue to pale blue to dark blue gray. Partly cloudy to overcast conditions will also influence the color make-up of the horizon’s backdrop. These effects are also influenced by varying atmospheric conditions, direction of view, distance between the viewer and the wind turbine generators, and elevation of the viewer. The only constant to visibility is that it is always changing. However, if less visual contrast is more commonly apparent in the morning hours, then it is likely that the visual contrast may be more pronounced in the afternoon. The inverse is possible, as well.
Should any offshore wind energy leases be awarded and project plans submitted, project-specific visual simulations will be prepared by a lessee and submitted with a proposed Construction and Operations Plan (COPs) for comprehensive regulatory and environmental reviews. See:
- Guidelines for Information Requirements for a Renewable Energy Construction and Operations Plan
- Guidance on Information Needed for Issuance of a Notice of Intent (NOI) Under the National Environmental Policy Act (NEPA) for a Construction and Operations Plan (“NOI Checklist”)
- Seascape, Landscape, and Visual Impact Assessment (SLVIA) Methodology
Instructions for Viewing the Visual Simulations
Photo simulations are presented in two formats: Panoramic photo format, which approximates the human-field-of-view; the other is single frame photo format that is equivalent to a photo taken with a 50 mm lens on a 35 mm full-frame camera, which represents the “normal” camera lens field-of-view. Each format set has a purpose.
The panoramic photo format approximates the 124° human field-of-view and illustrates the horizontal breadth a person may see when standing at the location and looking in the direction the photo was taken. This photo informs the viewer how much of horizontal span of view would be occupied by the project without moving the head from side to side. However, the panoramic photo simulation does not properly illustrate the vertical size and scale of the wind turbines and other offshore facilities associated with the wind energy development.
The series of 5 single frame photo simulations are a photo-equivalent to a 50 mm lens on a 35 mm full-frame camera, which more accurately approximates the vertical size and scale of the project’s offshore wind turbines and other associated offshore facilities that people would see from the photo-point location. However, the horizontal field-of-view in the single frame photos are considerably less than the 124° human field-of-view.
BOEM recommends viewing both sets of photos in unison and in accordance with the instructions below for viewing printed photos or on-screen viewing to fully understand the overall horizontal and vertical size and scale of the project represented in the photo simulations.
- Online viewing: Each simulation has a scaling bar with instructions to what length to zoom the bar. Once the scale is set, it is likely that the simulation will be larger than the monitor’s screen requiring panning across the screen to view the full context of the simulation.
Images viewed digitally are representations and the visibility of the turbines projected on a computer screen will depend on the scale at which the image is being viewed. Simply put, zooming in on the image will over-represent visibility and, conversely, zooming out will minimize visibility of the turbines.
- Viewing printed simulations: The simulations are intended to be viewed as large high-resolution printed panoramas printed on photo-quality paper, while the images are okay to be viewed flat, for full experiential accuracy they are best viewed when properly mounted onto a curved stand and placed at a typical viewing distance based on the image width. The panoramas cover a field of view 124-degrees horizontally by 55-degrees vertically, which is consistent with the typical human field of view.
11 x 17 printed simulations on bond paper are not optimal for viewing but are more convenient than large format prints on photo-quality paper. 11 x 17 prints should be held 19.7 inches away from the viewer’s face when viewing.
Visual Simulations
BOEM consulted with the National Park Service in selecting three key observation points (KOPs) along the Cape Cod National Seashore. The KOPs were chosen with the goal of representing a range of elevations, times of day, and viewing angles. The visual simulations depict a hypothetical offshore wind project. Please read the information above prior to viewing the simulations of hypothetical offshore wind projects.
- KOP1: Top of the Highland Lighthouse
- Photography was taken in the morning to simulate a “back lit” scenario.
- Viewpoint elevation: 167.93 ft
- Camera height: 5.41 ft
- Visual simulation
- KOP2: Marconi Wireless Station (top of bluff)
- Photography was taken mid-day to simulate a “front right lit” scenario.
- Viewpoint elevation: 108.61ft
- Camera height: 5.41 ft
- Visual Simulation
- KOP3: Nauset Beach
- Photography was taken in the early evening to simulate a “front lit” scenario.
- Viewpoint elevation: 14.07 ft
- Camera height: 5.41 ft
- Visual Simulation