Efforts to expand the number of offshore wind farms has sparked fierce debates in communities around the globe. While governments and policymakers view offshore wind as a central pillar in the transition to renewable energy, many citizens of coastal communities are vehemently opposed to the technology. Protests and anti-offshore wind groups can be found in coastal towns along the eastern United States, as well as in Galicia, Spain, northern France and other regions where projects have been proposed.
Anti-offshore wind sentiment is based on many factors. High on the list of grievances, however, is the environmental toll of the projects. Opponents cite whale deaths, disruption to bird migration patterns, and a host of other ecological consequences as reasons alone to scrap the projects.
What can be surmised about the ecological impacts of offshore turbine development? While there is still much to learn, here are three research-backed ecological effects of offshore wind development.
1. Underwater Noise Levels
Engineers have developed various techniques to attach wind turbines to the seabed, but the most common is pile driving–which can create dangerously high noise levels in the surrounding aquatic environment. It’s also important to know that sound travels faster in water than in air, thus making it appear louder.
Loud sounds emitted during turbine pile driving could cause irreparable hearing damage to marine mammals in the construction area. Large whales are considered to be especially sensitive to the low frequency sound produced during pile driving.
However, once wind turbines become operational, underwater sound levels are unlikely to reach levels that would be of concern to marine wildlife.
Furthermore, there is growing interest in floating windmills, as opposed to those that require pile driving. If floating windmill technology becomes the industry standard, underwater noise levels during windmill construction could be reduced significantly.
2. Bird Collisions
An operational wind farm poses other environmental dangers. One is the deleterious effect it might have on marine birds. Birds are susceptible to colliding with wind turbine blades. Circumventing wind farms comes at an additional caloric cost to birds that breed or forage in the vicinity. Migration patterns might also be affected.
Recent science has proposed a clever solution to the windmill-bird collision problem. According to a study published in Biological Conservation, selectively stopping turbines with the highest mortality rates reduced avian fatalities by 50%. And, unique data signatures captured by weather radars may be the key to knowing when to turn the windmills on and off, thus maximizing energy production while minimizing disruptions to avian birds.
3. Electromagnetic Fields
The energy produced by offshore wind farms is typically transmitted back to shore via underwater cables. These cables emit electromagnetic fields, which have been shown to adversely impact various aquatic species, such as elasmobranchs, teleost fish, decapod crustaceans and sea turtles.
Research, however, suggests some powerful ways to mitigate these effects. For one, not siting the cable lines near where sea turtles are known to nest, or where there are high densities of species known to be adversely affected by electromagnetic fields, is a possible mitigation technique. Other mitigation techniques include burying the cables deep enough to minimize seabed effects. If burying the cables is not an option due to topographical constraints of the seabed, then covering cables with rocks or concrete mattresses is another option. Also important is the cable design (e.g., placing the cables as close together as possible and using metal sheaths/armoring) and cable voltage (higher voltage cable systems produce lower magnetic fields than lower voltage systems for the same power delivered).
Amidst the many dangers, there are also possible ecological benefits of offshore wind development–beyond the obvious benefit of increasing clean energy production.
“Wind turbine foundations may act as artificial reefs, providing a surface to which animals attach,” state the authors of one study. “Consequently there can be increases in the number of shellfish, and the animals that feed on them, including fish and marine mammals.”
Furthermore, scientists speculate that wind farms may have a “sheltering” effect on marine ecosystems, closing off large swaths of the ocean to shipping and fishing activity. Other research suggests that there may be an opportunity to combine offshore wind farms with aquacultural projects.
There are currently hundreds of offshore wind farms producing energy around the globe, with China, the United Kingdom and Germany leading the pack. Many more are expected to come online over the next decade.
The ability of the engineering and construction community to develop creative solutions to the many physical and ecological problems they will inevitably face will likely determine the fate of the nascent offshore wind industry.
