3.4.4. Environmental impacts
Potential impacts of offshore wind on the environment include effects on fisheries, seabed communities, and migratory birds. Additionally, vibrations from the windmills could disturb marine mammals. Currently, there is no evidence of damaging effects from offshore wind turbines, but insufficient studies on environmental impact have been conducted.
For offshore wind farms, visual impact and noise pollution should be minor if the farms are not visible from shore [39]. While most plants to date have been sited very near shore in shallow water, it is anticipated that as the economics of offshore plants improve, future plants will be built farther from shore and in deeper waters, where visual and noise impacts are greatly reduced [37].
One of the few noted environmental drawbacks of wind power in general is the potential to kill birds. Careful siting of windmills to avoid important bird migration corridors can significantly mitigate this danger. Empirical studies have concluded that diving birds at Tuno̵ Knob in Denmark are not frightened from the sites of wind farms [36] and [39], and that bird mortality from collision with windmills at Blythe Harbor, UK is significantly lower than background mortality [40]. With careful siting to avoid harm to local or migratory birds and fish, offshore wind may be one of the most environmentally benign of ocean energy resources, as it has a very small footprint, does not affect currents, waves or tidal flows, and does not discharge fluids or change the ambient temperature of the waters [37].