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Seatower's game-changing wind turbine foundations could reduce the cost of offshore wind farming

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May 13, 2014

Seatower: bringing down the cost of offshore wind farming

Seatower: bringing down the cost of offshore wind farming

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Offshore wind farming combines the clean, green, environmentally neutral benefits of land-based wind turbines, while being a lot less visually intrusive ... and restricting the usual NIMBY opposition to crustaceans and invertebrates. It's currently a lot more expensive to install turbines out at sea, though, and that's restricting the sector's development. Which is why the Seatower Cranefree turbine platform could be such a significant step forward. Cheaper and easier to install, and requiring less gargantuan and specialized equipment than standard monopile foundations, the Seatower base could help offshore wind farms reach profitability a lot quicker.

Wind farms are one of the cheapest, greenest and most reliable forms of energy generation. One modern turbine can now power more than a thousand homes, and in many areas they're becoming a significant part of the energy mix.

Offshore wind turbines are even better in a performance sense, and they're a lot further out of the way, so fragile petals like conservative Australian Treasurer Joe Hockey don't have to endure the "utterly offensive" sight of clean energy turbines on their way to work in the morning. Strange how conservative politicians seem to find open-cut coal mines far less offensive.

Still, up to this point, offshore turbines have been much, much more expensive to install. That's because there's a lot of challenges to overcome when you're trying to drive a massive monopile foundation into the sea bed.

For starters, the monopiles are huge, they weigh up to 650 tons each, and they require large, expensive ships to transport them. Ships that can drop legs down to the sea floor and elevate themselves above the waves to provide a stable platform that a giant crane can operate from. Very specialized, very rare and very expensive gear that works in a fairly narrow range of weather conditions.

Seatower: bringing down the cost of offshore wind farming

Norway's Seatower foundations offer a much cheaper installation process that works roughly like this: firstly, the bases are mass-produced and assembled on land. Next, the hollow bases are lowered into the water, where they float in a stable fashion.

From there, they can be towed to the install site by a fairly small boat, at which point two more boats string a line to the base to position it precisely above its resting place.

At this point, a valve opens and water is let into the base to weight it. The structure sinks gradually to the ocean floor. A steel skirt around the outside of the base digs into the sea bed to anchor it, and concrete mix is poured into the gap between the base and the sea floor to provide a 100 percent contact between the base and the ground.

A sandy slurry is then pumped into the top of the structure until it achieves its target weight (usually between 6,000 and 7,000 tons), and then the base is ready for the turbine to be stuck on top of it. Even though this step likely requires the very cool jack-up crane ship to come in, it's certainly required for less time.

Should the tower ever need to be decommissioned, the above steps can more or less be followed in reverse, floating the base back up to the surface and leaving very little effect on the surrounding environment. Except, of course, a few squashed crayfish.

Seatower: prefabricated and assembled on land

No undersea work is required from divers or submersibles, there's no drilling or hydraulic hammering required to seat the foundation.

"Seatower Cranefree Gravity is most applicable for water depths ranging 35 - 80 meters (115 - 262 ft)," Seatower's Niels Brix tells us. "However in some cases, where you i.e. have rocky seabed (and therefore cannot drill/pile), you might use it at less than 35 meters."

The technology will be demonstrated in early 2015 with a single Seatower and turbine to be installed at the Fécamp wind farm site off the coast of Normandy, France.

Brix believes the relatively simple Seatower installation process could have a significant impact on the high cost of offshore wind generation. "The concept will certainly, taken to larger scale manufacturing, help to drive down the total CAPEX of an offshore windfarm," he says. "Our foundation is easier and much less costly to install than typical steel structures using special purpose vessels and offshore jack up vessels."

While Western Europe, Scandinavia and the British Isles offer immediate opportunities, with large areas of relatively shallow seas, large populations close by and good strong winds, Blix says Seatower has global ambitions. "Many sites in the USA and Asia are potentially very interesting to us."

Power generation is a money-in, money-out game. Coal and gas fired power plants persist not only because of entrenched business and political lobbying, but because they make good economic sense.

Right now, offshore wind is expensive and makes less economic sense. If Seatower and other technologies can help bring the cost of offshore wind generation down, more turbines could be installed offshore where they're not "a blight on the landscape" or "a health hazard," and the likes of Joe Hockey will have to find some other reason to oppose them.

Source: Seatower

About the Author
Loz Blain Loz has been one of Gizmag's most versatile contributors since 2007. Joining the team as a motorcycle specialist, he has since covered everything from medical and military technology to aeronautics, music gear and historical artefacts. Since 2010 he's branched out into photography, video and audio production, and he remains the only Gizmag contributor willing to put his name to a sex toy review. A singer by night, he's often on the road with his a cappella band Suade.   All articles by Loz Blain
11 Comments

It could ?

It would ?

It should ?

watersworm
13th May, 2014 @ 01:07 am PDT

I am pretty sure the seabed under the tower will settle much like the sand under that famous bell tower in Pisa.

Slowburn
13th May, 2014 @ 01:26 am PDT

@Slowburn

I am pretty sure the designers thought of that.

LordInsidious
13th May, 2014 @ 09:41 am PDT

All these ocean based wind farms are missing a good source of energy. The wind should be only one part of the energy mix. They should have a turbine under the surface to harvest the power of the ocean currents and the waves.

HenryFarkas
13th May, 2014 @ 09:47 am PDT

Stanford's Mark Jacobson is putting forward a plan to power the world economy fully with wind, water and solar (WWS) by 2050 with http://thesolutionsproject.org

Advances like these make this approach ever more feasible.

More data on US and worldwide implementations are here:

http://www.stanford.edu/group/efmh/jacobson/Articles/I/WWS-50-USState-plans.html

moreover
13th May, 2014 @ 12:19 pm PDT

You can partly integrate the power generation of these windfarms with pumping water up a hydro-electric dam during times where not a lot of power is needed (i.e. at night). During the day, you can use the stored energy of the water to run the hydroelectric dam at a total efficiency of 80%. This partly solves the intermittent power source problem of winds, thanks to the fast response time of dams to adjust their generated power.

Unfortunately, the hydro electric dam capacity in the developed world has reached a stadium where there isn't a lot of room to expand. Not to mention the local region impact of building one.

Fretting Freddy the Ferret pressing the Fret
13th May, 2014 @ 03:00 pm PDT

Pumped storage is effective if done properly and there is a place it can be constructed. For the good and bad sides of this see :

http://en.wikipedia.org/wiki/Taum_Sauk_Hydroelectric_Power_Station

Not long after it was built some friends and I were bicycling in the area and rode our bicycles up the mountain and around the reservoir. We had no idea what it was and had a lot of fanciful theories. When we got to the end of the road that went most of the way around it we had to climb up to the top of the wall to see what it was all about. And being downwind on a very windy day got a face full of spray. We each had to have a look for ourselves. Finding a big lake on the top of a mountain. is not something you would expect. It took a while to decide what it was for as we had never heard of doing something like this.

Intellcity
13th May, 2014 @ 09:32 pm PDT

Joe Hockey was horribly quoted out-of-context by a dimwitted reporter - he was offended by the financial unsustainability of wind farms, not their aesthetics (bloody obvious - he's our Treasurer, how the heck the idiot reporter who heard him talk failed to grock what he said continues to amaze me).

If you watch the interview (or pull out your calculator and do some basic maths), you'll find that coal is *way* cheaper.

And, before you get started on CO2 arguments, show me how you plan to convince everyone in the developing world to stop cooking, or all industrial peoples to stop making stuff, first. We're stuck on a rock with 7.1+billion people screwing it up, and there's not a licking thing anyone can do to stop it.

Yes - YOU can make a difference, and windfarms will help, but no, nobody will ever notice what difference you or windfarms will actually make, because it's nothing more than a drop in the ocean.

christopher
13th May, 2014 @ 09:52 pm PDT

Freddy there are a lot of existing dams that are rarely if ever full - eg. Lake Mead (Hoover Dam) hasn't been full for over 30 years and with climate change on top of fresh water demand that is looking likely to remain the norm rather than the exception

So there is considerable capacity within the existing infrastructure for pump up hydro.

Reason
13th May, 2014 @ 11:21 pm PDT

Christopher, apart from indirectly calling Alan Jones a "dimwitted reporter" (hard to disagree, although real reporters should take offense) , Hockey is on record on his own web site, and there is nothing out of context about it. Jones was trying on his tired old denier spiel but clear as day, Hockey just thinks the wind farms spoil his chauffeured drive to work;

http://jbh.ministers.treasury.gov.au/transcript/028-2014/

Reason
14th May, 2014 @ 03:09 am PDT

@christopher

How do you get up in the morning with this belief 'We're stuck on a rock with 7.1+billion people screwing it up, and there's not a licking thing anyone can do to stop it.'? Love the straw man argument about CO2, because cooking fires are a major contributer to AGW and there is absolutely no way to power a factory without burning something. /s

With such a dreary outlook how do you continue on?

LordInsidious
14th May, 2014 @ 10:35 am PDT
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