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To take advantage of the North Sea wind, we must understand


December 22, 2021

For countries with easy access to the shallow, windy North Sea, offshore wind is key to achieving the Net Zero goal. The development of these wind farms is partly a challenge for engineers, but it also depends on the geology below the seafloor. Earth scientists like us are coming.. As the industry collects more data, the geology of the seafloor is much more complex and clear than previously envisioned.

Over the past millions of years of on-off ice ages, large ice sheets have advanced and retreated many times over Northern Europe. This changed the landscape and caused changes in sea level. Britain’s current coastline provides a snapshot of this changing landscape, but sinking beneath the ocean is a much more complete archive of recent Earth history.

For example, Dogger Bank, a shallow area in the central North Sea where wind power is likely, About 8000 years ago.. Fishing boats occasionally drag prehistoric tools and relics from the people who lived there. We now know much more about these cycles of ice advance and retreat, thanks to the vast areas of the North Sea being investigated for the development of offshore wind farms.

An example of a seafloor cross section in the southern part of the North Sea. It shows different layers of sediment where the turbine and cable intersect. Quoted from Eaton et al Journal of Quaternary Science (2020), Courtesy of author

We are geoscientists Map layers of these deposits Under the seabed. Each layer tells us something about the world when it was deposited. Some layers are glacier deposits, which are bullish by the movement and pressure of the ice above, and in some places there are glacial lakes formed from water melting from the ice sheet. Other layers show that as the ice receded, land landscapes were formed by a complex network of river channels meandering through forests and flark.

As the ice sheet melted towards the end of each ice age, sea level rise flooded the landscape. This is known because these warm sands and silts contain shells. This cycle of destruction as the ice progresses and repairs as the ice recedes and floods the land has resulted in a complex arrangement of sedimentary layers.

Three maps of the seabed
Dogger Bank wind farm data reveals a submerged landscape. A) Glacial landforms provide evidence of ice sheets 23,000 years ago. B) The retreat of ice left a shallow relief land landscape dissected by an early human-attracting river. C) Formation of sand spit when the landscape becomes coastal and settlers are forced to move before the sea floods. Adapted from three studies by the author (lead author Andie Mary) published at Dogger Bank, Courtesy of author

A closer look at these past environments will give us a better understanding of how landscapes evolve in response to changing climates. Studies of this property have been carried out on land for centuries, where geological records are frustratingly fragmented by traces of erosion and human development. By comparison, thanks to unprecedented detailed data collected to support offshore wind power, the transition from the Ice Age to warm landscapes tens or hundreds of kilometers can be tracked.

In the North Sea, this reveals that multiple cold-temperature cycles leave different deposits under changing climate and sea level. These complex ground conditions can make the installation of wind turbines and interconnect cables very problematic. Different types of sediments pose different challenges..

Hard glacier clay often provides a strong foundation for turbines, but coarse sea sand is prone to erosion from around the base tower and can be unstable. Peat formed during the warm climate before sea level rise poses specific challenges as its fibrous nature makes it difficult to dig and reduce the efficiency of cables that transfer energy on land. increase.

Detailed seafloor mapping allows the offshore wind industry to plan more efficient and custom installations at each wind farm site, with resolutions never before possible or considered. Also, as sea level drops by more than 100 meters during each ice age, many other submerged continental shelves currently planned for offshore development will eventually be exposed. Over the past millions of years, this changing landscape brings diverse and complex layers of sediment at potential offshore wind farm sites around the world, whether near or far from previous ice sheets. .. conversation


author

Natasha Barlow, Associate Professor of Quaternary Environmental Change, University of Leeds When David Hodgson, Professor of Sedimentology and Stratigraphy, University of Leeds

This article will be republished from conversation Under a Creative Commons license.read Original work..

https://www.oedigital.com/news/493036-to-harness-the-north-sea-winds-we-must-understand-its-complicated-seabed-geology To take advantage of the North Sea wind, we must understand

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