Lewis Wind Power predicts that the development would not only help Scotland reach its goal but it would also generate 10 to 14 million U.S. dollars (6 to 8 million pounds sterling) of annual income for the Western Isles.
"The Western Isles has been identified as an area facing particular challenges," said John Price, Lewis Wind Power's development director.
"The population is declining, unemployment is high, activity rates are low, and gross domestic product per head is well below the national average. The development has been designed to be large enough to provide real economic benefits to the Western Isles."
But the scale and location of the wind farm would cause serious harm to the region's bird life, according to RSPB Scotland's McCall.
One concern, she says, is that large birds like golden eagles risk being chopped up in the massive turbine rotors, which measure 320 feet (100 meters) across.
"Eagles hunt over large areas, and they focus quite closely on what they're trying to hunt rather than on turning blades," McCall said.
"Collision risk is also a big problem for large birds like divers, geese, and swans, which have dedicated flight lines.
"The idea of birds flying into objects may sound a bit odd, but they'll be flying in all types of weather conditionsfog, cloud, mist, rain, and wind."
Models for collision risk predict that birds will avoid the turbines 95 percent of the time.
"Even then you're looking at losing 50 golden eagles over the 25-year lifetime of this development," McCall said.
Collision-risk estimates suggest a similar death toll for merlin, a species of falcon, and the loss of between 200 and 250 red-throated divers.
An even bigger threat from the proposed wind farm is potential damage to the peatland breeding habitat of wading birds like greenshank, dunlin, and golden plover, McCall said.
"These birds don't like tall structures or moving blades, so they will move away," she added.
Lewis Wind Power says only one percent of the habitat will be disturbed by development, but an RSBP-commissioned study suggested the potential impact could be up to 30 times greater.
Tom Dargie, ecologist for Lewis Wind Power, says he's "deeply concerned" by RSPB's response to the developer's environmental survey.
"Senior, very experienced peatland ecologists" at Scottish Natural Heritage, Scotland's independent government conservation agency, agree with Lewis Wind Power's estimates of the farm's environmental impacts, he said.
But Lewis Wind Power concedes that there will be some cost to local wildlife. For example, the developer projects that four percent of the British population of dunlin could be affected.
Lewis Wind Power's Price counters critics by saying the project will contribute significantly to the fight against global warming, "which the RSPB acknowledges as the greatest threat to birds and bird habitats."
"We acknowledge there are concerns about the impacts of the proposal on birds and on the landscape of north Lewis, and [we] have worked hardincluding commissioning the largest bird survey ever undertaken in Europein developing the design to minimize these impacts," he said.
Price adds that the wind farm would benefit the Western Isles economically, creating more than 300 jobs, plus another 350 jobs over 25 years.
While the regional council has backed the project, there is strong opposition from local residents.
About 3,200 Lewis residents have issued formal objections to the proposed wind farm.
Former Western Isles Member of Parliament Calum MacDonald, who was voted out of office during national elections last May, blamed his defeat on his support for the plan.
His defeat, he said, "was a protest vote against [the wind farm]."
Wind-farm opponents say any economic benefits to the Western Isles would be outweighed by lost tourism revenue.
Lewis resident Justin Busbridge is one such critic.
"It is often said, You can't eat a view, but tourism operators and thousands of islanders earn their living from just these views," he commented. "If they are destroyed, so is their livelihood."
Busbridge, who runs an adventure business, says tourism represents 20 percent of employment in the Western Isles, providing 2,300 jobs.
A survey by VisitScotland, the national tourist board, found that 50 percent of visitors felt that wind turbines would spoil the scenery, while 25 percent said they would be "less likely" to return to an area with turbines.
The RSPB Scotland says it supports wind farms in principle and other forms of renewable energy, and objects to only around 10 percent of proposed wind power schemes it's consulted on.
"We must be very careful to make sure that renewable energy developments themselves do not pose a threat to important bird and biodiversity resources that we are trying to protect," RSPB Scotland's McCall said.
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