Block Island Wind Farm

Challenge

• Provide 100% renewable energy for all residential households and tourism on Block Island.
• Reduce noise pollution produced by diesel generators.
• Provide aquatic habitat for marine animal species.
• Reduce any negative visual and environmental impacts of wind turbines
• Provide educational opportunities about wind power.

• The Block Island Wind Farm provides electricity to all residents of Block Island (slightly over 1,000 residents representing approximately 443 households) as well as tourists, with additional energy provided to mainland Rhode Island and beyond, replacing carbon-based energy (diesel generators) with renewable energy. After the completion of the Block Island Wind Farm, the previously used four diesel-fuel generators continue to be maintained for planned outages or as backup for unexpected outages.
• The project’s 5 turbines are located 3.8 miles from shore, and each turbine stands 593 ft tall. The turbines are spaced approximately 0.5 miles apart and are arranged in a single radial array approximately 2 miles long, running roughly parallel with the southeastern shoreline of Block Island.
• Block Island uses a fixed-bottom jacket support structure, which is a type of turbine foundation with a lattice framework that uses multiple anchoring points to connect to the sea bed. Use of the fixed-bottom jacket allowed the project to reduce the use of steel and reduce costs by sourcing materials from fabricators in the United States. Installation of the fixed-bottom jacket is typically safer than installation of turbine foundations used in shallower water, and typically reduces ocean floor disturbance.

The landscape architect prepared a Visual Impact Assessment, which included visual simulations and a study of visual impacts of the 5-turbine project. High-resolution computer enhanced image processing was used to develop realistic simulations of the completed project, showing anticipated visual changes that would occur as a result of the construction of the turbines. The landscape architect also evaluated the overall design impact of the project by defining areas of similar landscape character, called Landscape Similarity Zones, based on features such as landform, vegetation, water, and land use patterns. These Landscape Similarity Zones were assessed based on landscape composition; form, line, color, and texture; focal point; order; scenic or recreational value; duration of view; atmospheric conditions; lighting direction; project scale; spatial dominance; visual clutter; and movement.

Assembly and installation of the Block Island Wind Farm cost an estimated $20,880,240 through the use of a flexible “Twisted Jacket” ocean floor anchoring system, compared to an estimated $26,100,300 for installation of a more traditional monopile anchoring system. The “Twisted Jacket” has fewer parts, resulting in a reduction in steel usage due to more efficient weight distribution. It is also faster to assemble than the monopile system while retaining the same anchoring capacity and ability to withstand storms.

Visual Assessment Process

• During the creation of the visual impact simulations from the Rhode Island mainland, the landscape architects were unable to accurately quantify how the curvature of the Earth would impact the visibility of the offshore turbines. Because of this, they visualized the turbines as if they were sitting directly on the horizon, instead of below it as would be expected due to the Earth’s curvature. In reality, only the tops of the turbine blades are visible from the Rhode Island mainland, meaning that the original visual impact simulations showed much greater visual impact than actually occurred.
• The visual impact simulations did not include quantifiable differences in weather and atmospheric conditions. This gave them a stark “crispness” that made the turbines appear far more noticeable than in reality, where offshore atmosphere and fog generally soften the views of the turbines. Representing the simulations without weather and atmosphere incorporated may not have conveyed the actual experience of the finished project, but it is the most conservative and forthright way to demonstrate to the public the full potential impact of the project.
• In the process of completing the visual assessment and evaluation, repetitiveness of reviewing over 100 photos for the specified criteria caused a certain degree of fatigue for the four landscape architects, which may have had negative impacts on the quality of the analysis. To address this, landscape architects modified or shortened several of the review protocols.
• The landscape architects determined that the predefined scoring values of 1-3 for visual quality as denoted in the Army Corps of Engineers’ Visual Resources Assessment Procedure did not allow for enough differentiation of visual impact between views. To address this, they created a 1-9 scoring scale that was later converted back to 1-3 for the purposes of adhering to the accepted methodology.

Project Team

Developer and Wind Farm Design: Ørsted, formly Deepwater Wind
Landscape Architect: Environmental Design & Research, Landscape Architecture, Engineering & Environmental Services, D.P.C.

Role of the Landscape Architect

The landscape architect provided visualization support to assist the project’s permitting and public outreach, including the creation of visual and scenic impact assessments after the phases of land acquisition and initial studies were completed. These assessments included the preparation of 28 photo-realistic visual simulations that were used in public meetings to demonstrate impacts to the visual character of the landscape, as well as authoring a Visual Impact Assessment report. The landscape architect also created the wind farm’s project website and an animated video flyover that has supported the project’s public outreach efforts.