As the demand for renewable energy gets higher and higher, offshore wind turbines will inevitably move further and further away from the shore. Fortunately, floating turbine technology will help facilitate this shift—but now, for the first time ever, areas of the UK continental shelf that are “seasonably stratified” are now open for development.
What does “seasonably stratified” mean?
According to David Attenborough, seasonally stratified waters are some of the most biologically productive waters on earth. Even though they only cover seven percent of the ocean, they account for around 10 to 30 percent of the life found at the bottom of the food web.
Seas that are seasonably stratified are thoroughly mixed in the winter, but as the seasons change to spring, the sunlit water becomes warmer and forms a layer over top of the colder water underneath. This separation is called “stratification,” and triggers an explosion of marine life as phytoplankton blooms in the surface waters, creating a base for the food chain that supports fish, seabirds, and whales.
Nutrients that are found in the sunlit surface layer of the water are quickly used up by the plankton bloom, which means that the growth of more nutrients depends on nutrients that are stirred up from deep down by turbulence caused by tides, winds, and waves.
On top of stirring up nutrients, this turbulence brings oxygen down into the depths where dead plants and animals are rotting. Oxygen is necessary for decay, so mixing the nutrients and oxygen can help the rotting process and transform what’s died into useful nutrients once again.
What do seasonably stratified waters have to do with climate change?
The changing climate is making stratification happen earlier in the year, which means plankton also blooms earlier, resulting in a life cycle that is out of sync with the lives of larger animals. During summer, stratification is expected to increase, reducing the ability of natural turbulence to stir up the vital nutrients from the depths and ultimately diminishing the ability to sustain marine ecosystems. Plus, a warming ocean holds less oxygen, which could potentially lead to poor water quality.
How do wind farms help this problem?
New research suggests that one of the byproducts of deep-sea wind farming is that the foundations of these floating turbines could actually reverse some of the damaging effects of climate change on seasonably stratified waters by providing an artificial source of turbulence.
The water that flows past the floating turbine foundations will generate wakes, and this will cause the warm and cold water to mix again. Research has already demonstrated that the wake caused by the turbine foundations at least doubles the natural turbulent mixing within the region of an offshore wind farm.
The hope is that this artificial turbulence could offset the impacts of climate change on stratification and allow oxygen to travel deeper while stirring nutrients to the surface layer. Not only will offshore wind turbines provide us with renewable energy, but if carefully designed, they can be an effective tool in saving important marine ecosystems.