Non-noise downsides of Offshore Wind

Our last three pieces on offshore wind covered noises from site surveys, installation, and operations. But there are other concerns not associated with noise which also need to be considered.

One of the top human concerns is disruption of the viewshed. It is commonly tossed around in the industry that the proposed siting of America’s first coastal windfarm off Martha’s Vineyard – in Senator Ted Kennedy’s viewshed, delayed the development of US offshore wind by ten years. The first wind project off Block Island was operating in 2016. And while the 180m (600’) structures can be easily seen from the island, the Block Islanders who I know are somewhat proud of them.

Of course this is Block Island, not Big Sur, so this pride won’t be the case in all locations. But accounting for the curvature of the earth, a 600’ tower located 30 miles offshore would not be visible from the shore. Of course this changes in California, where much of the coasts are cliffs with significant altitude – many higher than 600’(like Big Sur). What we can count on here on the West Coast is the very common offshore fog banks – particularly in the northern coasts. But they come and go, and once we know the turbines are out there, the horizon remains altered and tamed in our minds.

Another human-oriented concern comes from the fishermen. Many of the commercial and recreational fishing rules are in development, dealing with exclusion zones, gear entanglement, prohibition of certain equipment. And then there is the concern as to whether the electro-motive force (EMF) from the high-voltage power cables will negatively affect fishes – and sharks, and turtles, and lobsters…

It is known that many animals get navigation cues from the earth’s magnetic field. Will the significantly higher magnetic flux density from the cables skew their cues? Given that some creatures (like sharks) are more dependent on electromotive cues than others, how will this bias biological homeostasis over large ocean areas?

And then there is the forest of masts and jacks, transmission lines, cables, and tethers. Will these impede the migration and feeding of whales? Will they provide increased vertical feeding areas for fish, with algae, seaweed, barnacles, sea anemones, and other invertebrates recruiting onto these underwater surfaces – potentially increasing usable habitat for certain fish species? Perhaps these masts and jacks be used for ocean-restorative “vertical aquaculture.”

Then there is the bird mortality question. A Department of Fish and Wildlife sponsored paper states that the estimated bird mortality from terrestrial wind farms in the contiguous (terrestrial) United States is “not insignificant,” and estimated to be between 140,000 and 328,000 birds annually. That is a lot of birds, and most commonly raptors which see the mast as a good survey perch for hunting, but do not have the vigilance-imprint of a 300mph propeller tip chopping at them from apparently nowhere.

But these are terrestrial numbers. There are not a lot of raptors 20 miles or more out at sea. And offshore wind farms can be sited away from known bird migration routes, which are usually much higher than 600’ over water anyway.

So a lot of questions remain unanswered, or only partially answered. We do know that pivoting away from fossil fuel will be big, and thus have significant impacts on our planetary habitat.

But one thing is certain; we know that fossil fuels, when used as directed will kill the planet.