• Turbines under discussion off the coast of Bald Head Island and other Brunswick County beaches would be very tall — 853 feet from base to blade tip, with towers and blade tips all flashing simultaneously 30 times per minute in all directions
  • At 15 nautical miles (the Wilmington East wind energy area off Bald Head Island), the upper 770 feet (90 percent) of those turbines would be visible from a beach house on stilts
  • At 10 nautical miles (the Wilmington West wind energy area off Brunswick County beaches), the upper 834 feet (98 percent) would be visible

The previous brief in this series discussed the potential visibility of large arrays of enormous wind turbines placed off the coast of North Carolina. At present, those areas include the “Carolina Long Bay” wind energy areas, which would feature turbines 853 feet tall and be either 15 nautical miles offshore (Wilmington West) or nine nautical miles offshore (Wilmington East), and the Kitty Hawk wind energy area, which would feature turbines 1,042 feet tall and be 24 nautical miles from shore.

Wilmington East and Wilmington West offshore wind energy areas (“Carolina Long Bay”) and proximity to shore

Brunswick County residents were recently invited to an “open house” meeting with officials from the Biden and Cooper administrations (both of which openly advocate aggressive building of offshore wind energy facilities) and wind energy advocates. Concerned residents were told that they’d “likely only be able to see the turbines with binoculars.”

Previous analysis from the federal Bureau of Ocean Energy Management (BOEM) under Pres. Barack Obama had shown that the much smaller, earlier generation of offshore wind turbines (up to 577 feet tall) would be visually arresting features on the coastal horizon, especially at night. Furthermore, the Cape Hatteras Lighthouse, which reaches 210 feet above sea level (less than one-fourth the size of the turbines currently considered off Brunswick County shores), is visible up to 20 nautical miles according to the National Park Service.

Some things that should not be overlooked in the discussions of turbine visibility include:

  • the effect of vantage point on one’s visual horizon, owing to the curvature of the earth
  • how very tall the turbines under discussion would be from sea level to blade tip
  • how sensitive the human eye is to distant light
  • how many of these very tall turbines would make up the arrays

This brief will cover those topics.

Visibility of the Charlotte skyline

It’s well known that, given a clear sky, higher vantage points allow for people to see for longer distances. The Blue Ridge Parkway is dotted with scenic overlook vistas for that very reason. Many visitors to the North Carolina mountains have even been able to see the Charlotte skyline from Grandfather Mountain (80 miles away), Mount Mitchell (100 miles), and others.

Source: Grandfather Mountain account on Twitter

Not only is the state’s largest building, the Bank of America Corporate Center (871 feet tall) visible, but so are 550 South Tryon (786 feet), Truist Center (659 feet), and several other, smaller towers. Those are distinguishable 80 miles away, but also from a mile above sea level (and uptown Charlotte is 746 feet above sea level). The question is, how visible would 853-feet-tall wind turbines — a vast array of towers of comparable size to the Bank of America Corporate Center but filling an area over three times the City of Wilmington — be from lower vantage points? How about when they are all flashing repeatedly in unison at night?

Wind turbine visibility from a beach home on stilts

So far every visualization of wind turbines that would affect Brunswick County residents and beach tourists is made at the water’s edge – i.e., right at mean sea level — and made during the day. Even so, BOEM analysis in 2016 found that turbines as small as 328 to 492 feet tall — i.e., much smaller than 853 feet tall — could be seen unaided on a clear day from as far away as 23.5 to 27.8 nautical miles.

Effect of Earth Curvature on Visibility (Includes Refraction) — BOEM Illustration

Source: BOEM

The shoreline (sea level) perspective, however, is not the only view, and it certainly isn’t the one availed the most by coastal residents. How would turbine visibility change for people in a typical beach home on stilts, including in the evening?

To answer that question, I consulted the Earth Curvature Calculator and input distances in nautical miles to the turbine array, the heights of the turbines, and the eye level of the viewer (for a North Carolinian of average height either at water’s edge or viewing from the first level of a beach house at the location’s average elevation).

From the shoreline, an array of 853-foot-tall wind turbines 10 nautical miles offshore (such as called for in the Wilmington West area) would be highly visible. Only about the bottom 50 feet would be obscured by the earth’s curvature. So the upper 803 feet (94 percent) of the turbines would be visible.

At 15 nautical miles (such as called for in the Wilmington East area), the bottom 139 feet would be obscured, while the upper 714 feet (84 percent) would be visible. At 20 nautical miles, which was the distance discussed at the “open house,” the bottom 272 feet would be obscured, while the upper 580 feet (68 percent) would be visible.

These calculations are significantly different for someone viewing the ocean from a beach house on stilts. From such a vantage point on Bald Head Island:

  • At 10 nautical miles, only 19 feet would be obscured and 834 feet (98 percent) would be visible
  • At 15 nautical miles, only 83 feet would be obscured and 770 feet (90 percent) would be visible
  • At 20 nautical miles, only 190 feet would be obscured and 663 feet (78 percent) would be visible

Of course, at even higher vantage points (upper decks, second floors, condominium towers, etc.) those wind turbine arrays would appear more prominent. They would be even more so at night, as attested to by the BOEM viewshed analysis discussed in the previous brief. Because the human eye is so perceptive of light (even light as small as a candle flame can be seen for 1.6 miles), height is more important than intensity for light visibility. An array of massive turbines fitted with lights on the towers and blade tips all flashing simultaneously 30 times per minute in all directions would simply be impossible to ignore.

Coastal residents are right to be concerned — and for many more reasons than spoiled views. The “Big Blow: Offshore Wind Power’s Devastating Costs and Impacts on North Carolina” report from Locke’s Center for Food, Power, and Life provides a comprehensive look at many issues surrounding offshore wind.

The next brief in this series will discuss why negative tourism effects are to be expected from offshore wind turbine arrays — and look at how state leaders responded to a prior threat to destroy the viewsheds of another part of the state heavily dependent on tourism.