Satellite Captures a Surprising Impact of Offshore Wind Farms

Sediment plumes at the London Array in the North Atlantic. All Images: NASA Earth Observatory
Sediment plumes at the London Array in the North Atlantic. All Images: NASA Earth Observatory

Offshore wind power is taking off in Europe, but we’re still coming to grips with the environmental impacts of sticking gigantic steel towers in the oceans. One effect of these clean energy behemoths, however, seems indisputable: sediment plumes.

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Captured by the Operational Land Imager on NASA and the USGS’ Landsat 8 satellite, these striking images show us what looks like a bunch of jet skiers zipping across the North Sea in mathematically precise formation. In reality, these are vast wakes and plumes of suspended sediment generated by three enormous offshore wind farms.

Location of the Greater Gabbard wind farm, London Array, and Thanet wind farm in the North Atlantic.
Location of the Greater Gabbard wind farm, London Array, and Thanet wind farm in the North Atlantic.
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The London Array, pictured above, spans 40 square miles and produces up to 630 megawatts (MW) of power, enough for nearly half a million UK homes a year. To its north and south lie the Greater Gabbard and Thanet wind farms, respectively spanning 57 and 14 square miles and producing up to 504 and 300 MW of power. All told, wind farms in the North Sea account for roughly 70 percent of the European Union’s installed offshore capacity.

Sediment plumes and a boat wake at the Greater Gabbard wind farm in the North Atlantic.
Sediment plumes and a boat wake at the Greater Gabbard wind farm in the North Atlantic.

A 2014 analysis found that sediment plumes from offshore wind farms, which tend to align with the tidal current, can measure anywhere from 100 to 500 feet wide and stretch for several miles. What effect, if any, these plumes have on fish nurseries and marine life living in the shallow offshore environments of the North Sea is unclear.

Sediment plumes and a boat wake at the Thanet wind farm in the North Atlantic.
Sediment plumes and a boat wake at the Thanet wind farm in the North Atlantic.
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Proponents of offshore wind power tend to downplay potential ecological impacts, which are arguably less of a concern than the continued release of giga-tons of carbon into our atmosphere by the fossil fuel industry. But if offshore wind is to play a significant role in Europe’s (or America’s) energy future, the reality is that we’re going to need many, many thousands of turbines. It’s better we know what we’re getting ourselves into.

[NASA Earth Observatory]

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Maddie Stone is a freelancer based in Philadelphia.

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DISCUSSION

warriorscot
warriorscot

They are typically excellent for marine life, if you look into studies of marine predators in the UK waters you find that they use the offshore wind farms as feeding grounds(Moslty from SAMS and St. Andrews). Based on the background studies they almost always show enormously improved ecosystem productivity in the area that is a combination of the new environment and the fact they act as defacto marine protected areas.

The only real concern is the impact of potentially new environments on things like invasive species. The North Sea and most coastal waters around developed Northern Hemisphere countries are so terribly damaged that any productivity is a plus as compared to the baseline studies that often showed a nearly barren environment(largely due to over fishing from bottom dragging trawlers).

Also technically they aren’t really causing plumes of sediment in every case, the flow and sediment load is already there, what we are observing is wake turbulence in an existing larger sediment plume and vertical mixing that otherwise wouldn’t be present. It’s a little complicated, and there is a certain bit of pernicketiness about comparing a wake and a plume, but there are plenty of studies looking at it already including a lot of CFD models of it.

Honestly it’s one of the most researched topics going, there are several of the best universities in Europe(including several in the top 100 in the world) whose engineering departments are very much dominated by renewables research. I would say we do more of that than anything else and it’s billions a year. Right now most of my colleagues and myself who are working in offshore wind research are looking at the next generation, we know what we need to know and are looking at the long term impacts of operating them(not on the environment so much as the engineering and logistics). For me own research I’m looking mostly at end of life more than anything else and I’ve found other than the immediate impact of removal or remedial works the environmental impacts are a total non issue.