Maps show visual impact of wind farm

Tue, 05/24/2011 - 2:15pm
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These two maps, prepared three years ago for Deepwater Wind, give a rough indication of where offshore turbines would be visible from around Block Island.

On the left, colored areas show where people could see any portion of a turbine when trees and bushes are in leaf. On the right, the map shows the turbines’ visual impact when no vegetation or buildings are taken into account. The turbines would occupy a site three miles south of the island.

The analyses by Saratoga Associates show that summer visitors on the northern half of highly trafficked Crescent Beach would be able to see at least some portion of five turbines. The windmills would also be easy to see from the southern shore of the island, and high points everywhere. The top edge of one turbine would also be visible from Sandy Point at the island’s northern tip, where the North Light is a big tourist draw.

Deepwater’s island liaison Bryan Wilson cautions that the maps are just a starting point.

“They use bare bones assumptions, and they were part of the preliminary planning process,” he said. “They’re a great tool, but they need to be updated.”

Deepwater commissioned the maps for a presentation the company gave to the Rhode Island Historical Preservation and Heritage Commission two and a half years ago. At the time, the company was planning to use 3.6 megawatt turbines, which are 436 feet tall. But current plans are for bigger turbines, either 5 or 6 megawatts, which would sit about 50 feet higher, Wilson said.

The maps use topographical information from satellite images, but they’re not sophisticated enough to take any buildings, stone walls or other structures into account. And the map that includes vegetation assumes a solid 15-foot wall of greenery everywhere, instead of the variable landscape of trees and bushes that actually exists.

And, said Wilson, “We don’t know if they take into account the curvature of the earth.” The earth’s natural curve could be significant over the 10 miles between the turbines and the North Light, for instance, he said.

The state Supreme Court is currently considering an appeal from two manufacturers who charge that the offshore project will make electricity costs too high. If the court finds in favor of Deepwater, Wilson says the company will continue with its planning, including commissioning more maps. “We want very much to use this type of tool,” he said. “We want to make sure that we do it right.”

The Department of Energy sent out letters last week warning that federal funding for renewable projects is on hold. Jeff Grybowski, Deepwater’s spokesman, said that’s not a death knell for the project because the company has other financial backers.

The federal money “can be an important element in a financing package,” Grybowski said, “however there are alternative financing options as well. It’s too soon to know which set of funding options will be the final package.”