How offshore wind turbines could be more efficient

Aug 17, 2012
How offshore wind turbines could be more efficient

A Cambridge University study suggests that offshore wind farms could be 100 per cent more efficient in terms of energy payback if manufacturers embraced new methods for making the structures that support the turbines.

As wind farms are increasingly sited offshore rather than on land, and installed at water depths of up to 40 metres, a Cambridge University engineer is urging the wind power industry to look again at the design of the heavy supporting towers and foundations used out at sea in order to improve the energy payback achieved.

Jim Platts of the Institute for Manufacturing (IfM) believes that the wind power sector could achieve significantly higher payback ratios if turbine manufacturers used guyed towers (towers held in place by steel cables) made in composite materials rather than free-standing towers made in conventional steel materials.

A preliminary study undertaken at IfM suggests that payback ratios for could be doubled if the industry embraced new construction methods.

“The development of the wind turbine industry, and the way in which it works with the civil engineers who make the heavy supporting towers and foundations, which are not visible out at sea once the turbines are installed, mean that we have ignored something which is almost embarrassingly obvious in our race to meet the targets set for renewable energy production,” said Platts.

“We urgently need to reduce the high levels of energy embedded in offshore wind turbines which make them both ineffective in energy payback and costly in financial terms. We can do this fairly easily if we invest in more innovative methods for making and installing the towers and foundations that support them.”

The effectiveness of wind turbines is determined by a key figure: the harvesting ratio. This ratio is a measure of the energy it provides set against the energy embedded in it (energy used in manufacturing it).

Wind turbines comprise three main elements: the blades that harness the wind energy; the gearbox and generator mechanisms that produce the electricity; the tower that supports these moving parts and the foundations that hold the tower in place. The tower is conventionally made of steel and the foundation in steel and concrete.

For a turbine designed for use on land, the energy embedded in the moving parts represents two-thirds of the total energy invested in the installation while the supporting structure (tower and foundation) represents the remaining third. Onshore turbines typically achieve a harvesting ratio of 40:1.

When wind turbines are sited offshore, the towers required are both taller and heavier and the foundations more massive, using up to four times the amount of steel and concrete. “When you look at offshore you see a series of slim structures – what you don’t see are the far heavier supporting structures below the surface that they slot into,” said Platts.

Both steel and concrete are highly energy intensive to produce so the harvesting ratio of offshore turbines reduces to typically 15:1 – far lower than for onshore turbines.

On top of this, offshore turbines are subject to corrosion, which reduces the lifespan of the steel used. “Steel is prone to corrosion and to fatigue,” Platts explained. “This begs the question: could we do better with other materials. The answer is yes, we can use composites for towers just as we do for blades. They are lighter, stronger, corrosion free and more resilient than steel.”

A preliminary study undertaken by the Institute for Manufacturing suggests that guyed towers offer significant advantages over conventional towers. The use of steel cables, fixed to the sea bed by screw anchors, means that towers can be significantly slimmer as the tent-like guyed shape distributes the loads more efficiently to the seabed. Similarly, the foundations required are substantially less weighty.

The resulting reduction in the volume of steel and concrete needed means that a harvesting ratio of 25:1 can be achieved, the study concluded.

“The use of guyed towers is just the first step for the industry to take. The second step would be to make towers in composite materials which are less energy intensive to make than steel which relies on smelting and concrete that also depends on a chemical reduction process in manufacturing cement. Composites also have a longer life than steel as they stand up to fatigue much better. Using these new materials could increase the harvesting ratio still further to 32:1 and extend the lifetime of a turbine installation from the present 20 years to up to 60 years,” said Platts.

“The Finnish wind turbine manufacturer Mervento has shown the way with a guyed turbine designed for use in the Baltic. Other producers – such as those making turbines for sites in the North Sea – need to take heed and invest in research into designs that take a similar approach to making the industry far more efficient and sustainable.”

The wind turbine industry has experienced an average of 25 per cent per annum growth over the past 20 years. It has pioneered many composite materials developments that have benefited other sectors, such as aerospace. Wind turbine manufacturers use ten times more than the car and aerospace industries combined.

“It’s often overlooked that manufacturers of turbines have driven advances in composites, producing materials with 95 per cent of the performance of the high-cost composites made for the aeronautical sector at 5 per cent of the cost. Much of this work has been led by UK companies. These companies now need to look at new ways of working,” said Platts.

In the 1980s, Jim Platts developed the designs, the manufacturing processes, the team and the company that made all the large wind turbine blades in the UK. That team is now the Global Blade Technology division of Vestas, the world’s largest manufacturing company.

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NotParker
1.4 / 5 (23) Aug 17, 2012
"towers held in place by steel cables"

Translation: Our turbines aren't killing as many birds as we would like them to.
julianpenrod
1.9 / 5 (18) Aug 17, 2012
An eminent question remains. Namely that turbines convert energy from wind into electricity. But, when energy is taken from something, coverted into something else, stored or transmitted elsewhere, it ceases to exist where it was. Since wind energy is the movement of air, that means wind turbines will remove significant amounts of wind. And wind does many things. It equalizes temperature; it mixes air masses; it causes waves, which also has a purpose. I warned about land turbines and already it's being admitted air downwind of turbines is unnaturally warm. To be sure, many shills decried me saying, "Turbines will never affect the air at all." The climatic makeup of different parts of the U.S. are different, but look at the dispersal of wind farms in the Mid West and the extent of the dorught. there seems a close fit. Energy to fuel hurricanes is being taken from the air, which is why hurricane seasons since 2005 were lessened, but other arease are being hit differently.
Neurons_At_Work
4.8 / 5 (4) Aug 17, 2012
julianpenrod--
I think it's possible you are overestimating the effect humans have or might eventually have on the total energy distribution of wind:
"It is estimated that the energy contained in the wind accounts for approximately 2% of the total amount of solar energy that reaches the Earth, which represents almost two billion tonnes oil equivalent (TOE) per year (200 times more than the total consumed by all the world´s nations) although, in practice, only a very small part of this amount can be used, given its randomness and dispersion (around 5%)."
So if we are able to utilize ALL of the wind power available to us, we could harvest enough energy to power all of the world's nations 10 times over. We are currently harvesting--what?--maybe .01 percent of what could be harvested (likely less)? The Earth is big, the Sun dumps massive amounts of energy here, and I just don't think us puny humans are going to alter that energy balance much no matter how many turbines spring up--IMHO...
julianpenrod
1 / 5 (14) Aug 17, 2012
It would be frightening if Neurons at Work's "analysis" of the situation were a generally approved one
Consider, Neurons at Work "argues" that the total energy of the sun that goes into the wind is 2% of the total amount. So, because that's so small, affecting it would not affect much at all.
Consider a world without wind. With turgid, stagnant air hanging unmovingly everywhere. Cloud systems not moving. Thermal regions not displacing. Seeds not being distributed. Dust building up in all the low places. In such a world, all parts of the world will adopt a uniform temperature. A few bolts at crucial spots can represent a tiny fraction of a building, but can cause disaster if removed.
Lurker2358
2.3 / 5 (9) Aug 17, 2012
Energy to fuel hurricanes is being taken from the air, which is why hurricane seasons since 2005 were lessened, but other arease are being hit differently


You gotta be joking!?

You have any idea how much energy is in a hurricane?

We could make 10 times enough turbines to power all of humanit and it wouldn't effect hurricanes at all, it would certainly have less of an effect than all the pollution we make through burning fossil fuels anyway...
NotParker
1.2 / 5 (17) Aug 17, 2012
"Satellite data over a large area in Texas, that is now covered by four of the world's largest wind farms, found that over a decade the local temperature went up by almost 1C as more turbines are built."

Imagine another 10 million wind turbines not only bankrupting most countries, but raising temperatures.
julianpenrod
1 / 5 (12) Aug 17, 2012
It can take no more than a hbundred or so kilojoules to block up an active river and cut a diversion to an empty ravine. After a year, though, the energy that redirects can be significant. If energy even is only redirected, huge amounts of energy can be kept from one use by a small input of energy in a specific area. Consider, too, hurricanes are not always huge. At one point, they are small squalls, and a calculated realigning of the atmosphere at that point, even a minor one, can keep them from become huge later.
kochevnik
3.3 / 5 (12) Aug 17, 2012
"Satellite data over a large area in Texas, that is now covered by four of the world's largest wind farms, found that over a decade the local temperature went up by almost 1C as more turbines are built."
Wait you wrote before that temperatures were going DOWN !!!
You have any idea how much energy is in a hurricane?
Typical hurricane has the power of 480 hydrogen bombs. Penrod is hitting the bottle again...
david_king
1 / 5 (8) Aug 18, 2012
Maybe I'm daft but would these guy wires which are anchored to the bottom also connect to the top of the mast at the nacelle? If this is the case then the wires will be in the way of the blades when the nacelle rotates to capture changing wind directions. Presumably they would connect at the waterline and only stabilize the underwater portion.
Seems like we would be better served by a floating, autonomic sailing craft with a storage system or a tether. No one would complain about that blocking their million dollar ocean view.
Neurons_At_Work
5 / 5 (2) Aug 18, 2012
I believe Penrod's arguments are based on Edward Lorenz's 'Butterfly Effect'--chaos theory's 'sensitive dependence on initial conditions'. I don't discount this out-of-hand--I do however look at the alternatives and recognize that much more harm is being done and will continue to be done through the use of fossil-fuel based power generation than would be done using various alternative methods. Possible climate issues aside, (whether real or fictitious), the simple long-term health and economic benefits brought about by embracing SOME form of power production not dependent on coal, gas, or radioactive decay seems like a step in the right direction for our continued viability as a species. Call it the lesser of two evils if you like, but the key word is 'lesser'.
kochevnik
2.6 / 5 (5) Aug 18, 2012
What penrod fails to illuminate is how one goes about CONTROLLING outcomes of the butterfly effect, which are by definition UNPREDICTABLE due to infinite bi/tri/quad/frucation
julianpenrod
1.5 / 5 (15) Aug 18, 2012
So kochevnik is saying that, because a hurricane represents a huge amount of energy means it is impossible to prevent with a minor exercise of energy before the hurricane becomes fully formed.
Is kochevnik aware that simply not tossing a lit match into dry brush can avoid a massive forest fire? Or is kochevnik so rabidly determined to undermine everything I say that they will iungore all reality?
kochevnik
3 / 5 (6) Aug 18, 2012
Hate to break it to you, but until you invent a way to stymy vortex motion at every scale from the subatomic to the planetary, you have no useful control over hurricanes. Among other things you would need to stop the Earth's rotation.
86daily
1 / 5 (9) Aug 18, 2012
Instead of making all that effort collecting power from wind why don't we spend a little effort in collecting energy from the most powerful energy sitting around us. THE ATMOSPHERE. If UFO can sit over a lighting storm to energize their space ships then why can't we do the same. Oh, that's right that's all top secret hush hush. Your 40-1 ratio is nothing comparing to oil at 100-1 ration and 1,000,000-1 atmospheric collection. See KesheFoundation.com and open your eyes. I know this will be taken down quick. We wouldn't want the sheeples to know that the banksters are controlling information.
kochevnik
3.4 / 5 (5) Aug 18, 2012
@NotSmarter Translation: Our turbines aren't killing as many birds as we would like them to.
If you read the article, you would know that the preponderance of cable is underwater. And how many land-dwelling birds are in the middle of the ocean, exactly?
MarkyMark
3.4 / 5 (5) Aug 18, 2012
"Satellite data over a large area in Texas, that is now covered by four of the world's largest wind farms, found that over a decade the local temperature went up by almost 1C as more turbines are built."

Imagine another 10 million wind turbines not only bankrupting most countries, but raising temperatures.

Lol love this now 'not warming' Parker had admited that warming has occured but only because of wind turbines. Guess this is why he says global warming is real, for as he see's it all warming is caused by Turbines and birds live underwater!!!
ahaveland
3.9 / 5 (7) Aug 18, 2012
Debating anything with NotParker is like playing chess with a pigeon... No matter how true your facts, or how well you play, he'll knock the pieces over, crap on the board and fly off thinking he won.
NotParker
1.3 / 5 (12) Aug 18, 2012
@NotSmarter Translation: Our turbines aren't killing as many birds as we would like them to.
If you read the article, you would know that the preponderance of cable is underwater. And how many land-dwelling birds are in the middle of the ocean, exactly?


The turbines are sited 40m underwater. But offshore wind turbines are taller than 40m, so more cable is above the water.

These ones are 440 feet high.

http://www.wicked...3upPXG1s

Or even bigger ones: " 6 MW offshore wind turbine with a 154-meter rotor"

Many migratory birds fly over the water, and since wind turbines are usually just off the coast, then a wind farm would be an even bigger death trap.

NotParker
1.3 / 5 (14) Aug 18, 2012
"Satellite data over a large area in Texas, that is now covered by four of the world's largest wind farms, found that over a decade the local temperature went up by almost 1C as more turbines are built."

Imagine another 10 million wind turbines not only bankrupting most countries, but raising temperatures.

Lol love this now 'not warming' Parker had admited that warming has occured


Temperature always goes up and down.

From 1921 to 1977 Texas temperature dropped over 4F, and has since recovered.

https://sunshineh...1895.png

Surprisingly, no AGW cult member screamed about CO2 causing cooling in the 60s and 70s in Texas ...

or low temperature and high rain record falling lately:

http://mapcenter....max,rain

julianpenrod
1 / 5 (11) Aug 18, 2012
Vortex motion is not the key behind hurricanes' power. Water flowing down a drain spins in a vortex, but it won't knock a building down. It's the energy that is concentrated in the space of a hurricane that makes it dangerous. And if you can impede the concentrating of energy, you can keep a hurricane from happening. The recently wideley disseminated derechos can be as powerful as a hurricane, but don't need vortices, so there is nothing magical about them. The word, "vortex", though can convince the gullible and dim that kochevnik is right and anything else is wrong.
And it appears the obligatory retinue of gratuitous approval is back on the job, providing 5's at the drop of the hat, even if undeserved while making sure to give me only a 1 so that any later approval ratings will be diluted and decreased.
NotParker
1.3 / 5 (12) Aug 18, 2012
Debating anything with NotParker is like playing chess with a pigeon... No matter how true your facts, or how well you play, he'll knock the pieces over, crap on the board and fly off thinking he won.


"Sudden fluctuations in Germany's power grid are causing major damage to a number of industrial companies. While many of them have responded by getting their own power generators and regulators to help minimize the risks, they warn that companies might be forced to leave if the government doesn't deal with the issues fast."

http://www.spiege...419.html

That is reality.
Shootist
1.4 / 5 (11) Aug 19, 2012
Unicorn farts and pixie dust is all this will ever amount too.

Liberalism is is a philosophy of consolation for western civilization as it commits suicide.
geokstr
1 / 5 (8) Aug 19, 2012
"Satellite data over a large area in Texas, that is now covered by four of the world's largest wind farms, found that over a decade the local temperature went up by almost 1C as more turbines are built."

Imagine another 10 million wind turbines not only bankrupting most countries, but raising temperatures.


I hear the Chevy Volt will be offering energy saving options like rooftop windmills (except for convertibles) and solar cell paint jobs.
crackerhead
not rated yet Aug 26, 2012
not everyone has All the latest information ! The Sun drives our weather ! Something as simple as DUST will prevent storms from forming ! Sahara dust crosses the Ocean and blocks the heat from the Sun , so the heat that drives the storms is not in the water !The Sun drys the desert and produces the wind that carry the dust. Not only that but the Sun has cycles that effect Gaia ! We need more information !
crackerhead
not rated yet Aug 26, 2012
THINK Wave Energy !

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