The next big thing in wind: Slow wind, huge turbines

With politicians pushing adoption of renewable energy in the United States and Europe, the last few years have seen a surge in plans for wind farms--both on land and sea. But wind power isn't viable everywhere--and prime coastal spots are often already developed.

So some wind-turbine makers are shifting their focus toward building bigger wind turbines that can harvest the lower-speed winds that are more readily available. This next generation of wind turbines is no small matter: their rotors have a diameter the size of a football field.

In general, wind turbines get more powerful and efficient with taller turbine towers and larger areas swept by the blades, according to the American Wind Energy Association. A turbine's swept area is a key indicator in how much power output potential the turbine has.

"Lower wind-speed turbines certainly open up more land for development," said Rich Reno, platform leader for General Electric's new 2.5-megawatt wind turbine. "Larger turbines open up the opportunity to get more megawatts out of a given piece of land."

The Siemens SWT-2.3-101 has a maximum power output that's enough to power approximately 700 homes.

(Credit: Siemens)

Finding new sites for wind farms is essential to the sector's growth because many of the places with the most attractive wind conditions tend to be developed already. More efficient turbines also make wind power a more realistic option for countries like Germany, which is not very windy and has relatively limited shoreline, where winds tend to be stronger. Despite those obstacles, the country has the world's second largest installed base of wind power.

Wind farm development continues to push into new regions--particularly in the U.S. and parts of Europe, where politicians are encouraging renewable-energy R&D.

"We see continued growth in Europe, notably because of EU legislation to derive 20 percent of its energy from renewable sources," Victor Abate, vice president for the renewables arm of GE Energy, told Reuters in an interview. The European Union issued a directive in December 2008 to have 20 percent of its energy come from renewable sources by 2020. Europe contains more than half of the world's installed wind power capacity.

The U.S. is now the country with the world's largest installed base of wind power, according to the World Wind Energy Association. More than 8,300 megawatts of wind power was installed in 2008, expanding the nation's total wind power generating capacity by 50 percent in a single calendar year.

Although that growth is expected to slow in 2009, according to both the AWEA and investment bank HSBC, the wind industry is still getting support stateside. As part of the economic stimulus plan signed in February, President Obama extended tax credits for wind and increased the amount the government will spend on those credits by 30 percent.

Industry watchers predict much of the growth in the wind market will be in the low- to medium-wind segments. And as that trend continues, wind turbines in general have been increasing in size--from typical 18-yard rotors 25 years ago to about 110 yards in recent years. The average wind turbine installed in 2007, with a capacity of 1.6 megawatts, is twice as powerful as the average wind turbine installed in 2000 (0.76 MW), according to AWEA.

Several manufacturers are rolling out new low-speed turbines to help meet that demand. Siemens, Vestas, and Nordex all recently released new, large wind turbines directed at low-wind markets. Last year, General Electric released its largest turbine for low-wind use.

Siemens predicts that the low-wind market alone should represent one-third of the total global wind-power market in the coming years. Its new turbine, the SWT-2.3-101, has a "nominal" (that's maximum in wind-engineering speak) power output of 2,300 kW, enough to power approximately 700 homes, depending on wind conditions. The turbine is enormous, with a 110-yard rotor diameter--larger than an American football field.

A turbine blade convoy passes through Edenfield, U.K., with blades 42 yards long. Nordex's newer low-wind model, the N100, has a 53-yard blade--11 yards longer than the ones pictured. Transportation might prove to be one limit to how big land turbines can get.

(Credit: Paul Anderson)

Designed to harvest weaker winds, SWT-2.3-101 has a swept area of 86,111 square feet, 17 percent larger than Siemens' previous 2,300 kW turbine.

"The new wind turbine will open up many potential new sites for our customers," Andreas Nauen, CEO of Siemens' Wind Power Business Unit, said in a statement.

Danish wind-power company Vestas recently unveiled its V 112, a 3 MW low-wind turbine the company claims is the world's largest mass-produced wind turbine for low- and medium-wind-speed sites.

The wind turbine has a nominal power output of 3,000 kW, the same as the company's previous largest turbine. But because of its larger blade diameter, it's able to reach that potential with lower speed winds. It can generate electricity at wind speeds as low as 6.7 miles per hour and reach maximum power at about 31 mph. The previous model required 8.9 mph winds to deliver power, and 34 mph to attain maximum output.

Three factors have made it possible to make modern turbines so big, according to General Electric: controlling the load on the grid, new blade design, and new materials to reduce the weight of the turbine.

"As the technology increases in those areas it allows advancement," said Reno, of GE Energy.

New materials and construction techniques make it possible to build even larger wind turbines. Siemens says it uses a proprietary manufacturing process, which casts the 53-yard, fiberglass-reinforced epoxy blades in one piece. The process eliminates weaknesses from gluing parts together, as is done with traditional blades and thus makes it possible to make turbines this size.

Vestas is increasingly using composite materials and has a low-weight-design philosophy. In March, Vestas teamed up with U.S. aerospace company Boeing for projects in areas such as aerodynamics and composite-materials fabrication processes, design, and analysis.

But there are limits to how big these turbines can get. GE says the grid's ability to handle more powerful loads is one limiting factor. And in the future, problems with transportation could limit the size of new land-based turbines. Going around road corners and narrow bridges with 50-yard blades is already a problem, and the only thing that could alleviate that would be technology for making multiple-piece blades. Offshore this transport problem doesn't exist so the turbines could be bigger there. GE thinks the size increase of the turbines will plateau, but that won't happen for a while.

"I think 70 meters (77 yards) was a pretty big rotor 10 years ago. Today 110 is out there," Reno said. "Can they grow another 30 meters (33 yards) in 10 years? I think it is possible."

[agsGeoff]

Maybe I'm oversimplifying things, but wouldn't it make more sense to have hundreds of these scattered around the grid rather than having a farm all pumping in energy in one place. Wouldn't that make distribution easier? If part of the grid fails all the other turbines are still generating and adding energy

[dragonbite]

Not to mention as smaller impact on changing the overall wind flow.

I think they put them together in farms so they just need to run fewer long-distance lines to get them on the grid (a bunch of smaller pipes connecting to one huge pipe to the powergrid)

[ssejhill]

I think that 's what this article is about. Most areas only have a low to medium wind speed so wind turbines need to be developed and installed that can utilize and produce electricity at these slower speeds. As the technology is being developed and refined then we will see more diversification in where these wind farms can be placed. The more spread out the wind grid is ... the more uniform and continuous will be the power that results from it.

[gmhendo]

Having more sites reduces transmission losses to, which can be larger than 12%. But it also adds to management costs too. Plus, there is still a lot of nimby-ism out there to overcome - and there is not always the political will to confront that.
Effects on wind-flow and of turbulence don't seem to be well researched as yet. But climate change has been researched, and the urgent need for alternatives established. I would think that turbulence or not, wind-power should prevail over pollution.

[man290663]

We already have this in Europe where the standard turbines are much higher with larger baldes (larger swept area) and slower speed of rotation than the model used in the US which tends to smaller blades but faster rotation.

its simply a continuation of the current process used in Europe where efficiency matters more than sheer numbers as local planning consents here mean the number of turbines per site is limited (unlike in the US where wind farms can contain hundreds of turbines). Also the larger slower swept area also reduces the need for maintenance on bearings and reduces noise as well as improving efficiency.

[Warhaven]

I believe the much larger, slower-turning wind turbines are not only more efficient, but less prone to avian impacts, which has started to receive some attention here in the States with our smaller, fast-turning turbines.

[jonathanleistiko]

"And in the future, problems with transportation could limit the size of new land-based turbines. Going around road corners and narrow bridges with 50-yard blades is already a problem, and the only thing that could alleviate that would be technology for making multiple-piece blades."

I suspect that blimps would be a good way to transport blades of 53 yards or longer to remote locations. Assuming that wind farm locations are in or near relatively flat locations, it should be possible to set up a blimp tether there.

Yeah. I think that a blimp that could carry a heavy payload is the right answer. I wonder if it could carry the entire assembly (in pieces, of course)?

[Seaspray0]

Loved the post! Good job on thinking outside the box.

[4markowen]

I was thinking the exact same thing regarding Airships (blimps) you should check out the Skycat concept, which is designed for large/heavy loads and is designed to land with minimal ground crew, sans tethering. Could certainly be used for transportation, however for construction the kind of accuracy required to construct a wind turbine (hook rotor to turbine shaft) would be difficult to achieve IMO due to the very wind the turbine is trying to tap affecting the airship. wouldnt b cost effective to wait for the one or two days when wind is low...

also highlighting the main problem of wind turbines there, the inconsistent nature of weather...

[dadcss]

Can anyone tell me how the blades in general handle ice build up?

[Zoobie]

They have coatings on them to prevent ice build up, salt damage, and sand erosion. Some of the older designs didn't consider the ice build up, and houses/farms in the vicinity would get hit by big slabs of ice that would break off the blades.

[gmhendo]

The Danes have some experience with this. One solution is to heat the blades, but of course this consumes a lot of the energy produced by the device.

[Mindstrike]

Reminds me of the old radio dish days. Bigger was better. Then came the 13 inch home version and multiple dish arrays. I could use about twenty (low cost) small turbines. I better hurry though, our local electric company wants to put legislation in place to prevent people from producing their own power from residential wind turbines. I guess they want to maintain their monopoly..

Wouldn't it be possible to use multiple small turbines linked like battey cells to achieve the same overall power production? -- even at low wind velocities?

[jemiller0]

I read somewhere that the current tax credits for wind are only for large wind farms. I don't know the details of it, but, that's exactly what I suspected. i.e. the power companies lobbied for the breaks and probably talked the politicians out of giving tax credits to individuals.

[timber2005]

I think its more like
A) the tax credits can be more valuable in large purchaces because they stimulate manufacturing economy and
B) large scale turbines have a greater payoff (to the entire grid), where as home ones don't.

[RTFM]

They can use a heavy lift helicopter to deliver the large blades directly from the port or barge. You know, the two rotor ones. (There are not too many blimps available to do this.)

[RobHunterJohnson]

4150 megawatt last year? 8300 meg this year? How many megawatt does the united states have now? Rob

[timber2005]

According to: http://www.eia.doe.gov/cneaf/electricity/epa/epa_sum.html
The total energy production is 4,157 MWh [Million megawatt hours) in 2007

For all the breakdowns by source (solar, coal, etc): http://www.eia.doe.gov/cneaf/electricity/epa/epat2p2.html

[Maccess]

I'm not entirely convinced that massive wind farms are not messing up the planet's climate systems. These turbines take massive amounts of power from air movements that stabilize climate systems, and may be affecting climate negatively. We've been having massive storms, off-season bad weather, and torrential rains concentrated on limited areas.

[Seaspray0]

Which could be attributed to a multitude of sources, including sun spots, global warming, CO2 content, changes in ocean currents, amount of concrete now covering the earth, etc, etc, etc. Unless you can provide facts that prove the correlation, stop being a doomsayer. Would you rather have the electricity be generated from a dirty coal power plant?

[Spats30]

These turbines are not up in the jet stream, and therefore could not affect global climate as you suggest.

[Warhaven]

@ Spats30:

Not yet, they're not. However, there are several airborne designed for wind turbines to float up in the jet stream and generate power 24/7.

[cp256]

Airborne designs? OK, what keeps them in place and prevents them from just being blown away in the 100 to 300 MPH winds? Some sort of 5 to 9 mile long tether to the ground? How much would that weigh? Sounds a bit hokey to me...

[jemiller0]

I think it was on the Discovery Channel that they showed someone who was trying to create an air baloon that would spin around and act like a turbine. It didn't really work though and they said that if it did work that so many would be needed to generate the necessary power that it was pretty much impossible. I think one of the issue was where to get or how to produce all the helium that would be needed.

[RickMohr]

A Massachusetts company called FloDesign has an alternative turbine design based on jet engine technology which they claim is more efficient and easier to transport. This video explains the basics (if you can put up with the rock music): http://www.youtube.com/watch?v=RagPPrHUMTY

[askgees]

This is a stupid idea. Just what I want to look out on, a huge field of metal rotors. One bad idea after another.

[Sam Papelbon]

much prefer the smog-tinted field of decaying vegetation, would you?

[OlderThanOld]

In contrast to you, I find the sight of wind turbines near and far a very magical experience. I've always been fascinated by the juxtaposition of naturally occurring and man-made objects, and how they combine to form a unique landscape. Wilderness by itself can be a powerful thing to experience, just as can high-density urban environments. Throw the two together, however, and you get something more nearly approximating the world that most of us live in.

There's no escaping the fact that we live in a modified natural environment. Man's constructs are here to stay, or at least until man is no longer here. Six and a half billion people aren't going to exist without a huge human-built infrastructure. So, expecting to only have pristine wilderness around us is unrealistic, just as is expecting to be able to pay no attention to the need to care for the natural environment.

Getting back to my original point--what is so offensive about the turbine blades slowly turning in the wind atop their tall masts?

[galeso]

What is a few thousand dead endangered birds killed by rotors compared to our need for more electricity? :-)
Doesn't smog (CO2 does not create smog) reduce global warming? :-) Cough Cough.

OK, let me see if I got this right. Greenland and Antarctica are melting now, much faster than the computer models projected. If we reduce CO2 emissions to zero they will keep melting at the same rate. Most Democrats willing to let developed countries emit at 1970 levels (30% below 1990) and are willing to exclude the world's biggest emitter China. How are we not doomed?

[j_p_c]

galeso - People see birds, bats, butterflies, etc. that have died around turbines and think that's horrible, but emissions from coal fired electricity plants kill a lot more creatures than a wind turbine does over a larger area.

Particulate matter from coal plants may reduce the amount of sunlight that hits the ground, but a) we're breathing it (cough cough) and the particulates are often highly toxic. Remember acid rain?

I'll agree with you on the emissions reform though. It's pointless if we don't bring China and India into the fold. Of course, we'd better be prepared for prices of things from Walmart to increase once these countries realize the ecological catastrophes that they're creating (which give them financial advantages over the U.S. in creating cheap goods.

[myles taylor]

While these can be good, I think the trend should be to go toward smaller and more versatile ones that can go on roofs of individual houses and buildings. These don't matter which way the wind is blowing and can produce enough to power a house easily. We need to start mass producing these and getting government vouchers for them. The wind resources in the entire US are massive if you count the areas that aren't fertile enough for the big turbines but work just fine for these smaller ones. We need to think smaller, not bigger. Offshore I understand going bigger.

[lch41]

to add my 2 cents the wind doesen't blow 24/7 nor does the sun shine 24/7 what are we to use when
thay don't blow or shine or both ?

[jemiller0]

That is why battery technology is so important. You store the electricity in a battery so that it can be used later.

[timber2005]

Yes, you cannot rely entirely on wind or solar 24/7, unless you have excess capacity (eg, unused) and can store it (batteries, compressed air, etc). Otherwise, you need other sources such as hydoelectric or nuclear which provide 27/4.

[mikebellman]

The large turbines are built to help birds too. They don't spin as fast and birds can spot them and avoid them.

[gmhendo]

Emerging technology from China has them building wind powered turbines with a vertical axis. It's a bit like a squirrel cage fan that drives the heater fan in say, your car heater, but the axle is vertical.

A really interesting feature is that they are using maglev principles to reduce friction losses, greatly enhancing their low-wind capability. You can see it here:

http://www.inhabitat.com/2007/11/26/super-powered-magnetic-wind-turbine-maglev/

Or Google china maglev wind turbine for more sites.

You might also be interested to read that the turbines are increasingly efficient and responsive to prevailing conditions using innovations such as;

- Variable pitch blades (like aircraft propellers)
- Sensors in the blades that detect wind pressures and allow rapid response adjustment to the turbine as real-time conditions change
- There is great progress in the lithium ion battery, particularly in the charge rate of these batteries. Normally to re-charge an electric car takes hours. The new research can recharge an electric car battery is 5-10 minutes. One of the issues with wind power is its variability due to fluctuations in the wind speed. Now it will be possible to store power in the home for those times when the wind power is low. And because the batteries are fast charging, the best advantage can be taken for peak wind speeds in any time period. This will reduce the need for coal-fired generators to be on stand-bye to take up loads when wind is not enough.

[Yoerusho]

There are some huge Wind Power Turbines here in the Pennsylvania Coal Country. A stark contrast to the strip mining that is done in the area. These pictures at the link below are taken from about 10 -15 miles aways and there are about 10 or more along the top of the mountain. Pictures were taken from Centralia, where the underground mine fire was a few years ago.


http://www.flickr.com/photos/jbmac/sets/72157617858342305/detail/

[rturner2]

All that space on the turbine blades. Why not cover them in solar cells as well? And get power from both wind and sun at the same time?

[LLIB_SETAG]

Put a series of many smaller turbines tubes under large expansive bridges, such as Golden Gate, etc, etc... that way you can harness wind from under bridges, over canyons, over waterways, etc & turn public construction projects into energy sources.

Pays for the bridges & puts power back into the grid.

Put turbines, or vertical blades on top of skyscrapers to put power back into cities.
Great in Chicago "the windy city ".

[emanresu123]

Wind energy has an alarmingly low replacement value for fossil fuels even widely disbursed and interconnected across a system as wide as North America. Network wide output currently varies by as much as +1100% and -92% in less than an hour, causing fast-ramping natural gas generators to work harder and less efficiently balancing load to demand. Furthermore, demand spikes correlate poorly to wind spikes. The windiest periods occur when demand is lowest, and the calmest periods when demand is highest. Storage of grid scale electricity for later use is and will not become economically, technically, or environmentally sound nor safe in the next several decades.

Subsidies for off-shore wind development are no greater than subsidies for on-shore development, yet offshore development is still commercially viable at double the deployment cost, obviating the enormous waste of tax dollars shelled out for on shore development.

The whole wind industry is a sect of the global warming religion, and could never exist in a free market environment. The only sensible way to even allow intermittent resources onto the grid is to require the companion load balancing natural gas facilities to be constructed on site with each wind energy facility, and the emissions and fuel costs of those generators would reduce green credit and spot market pricing in general, making clear the limited value of wind power.

[lawrence18uk]

Yeah, airships, blimps - that's the way to carry big stuff - dunno why they bother with road transport at all now, must be so hasslesome with all the road permits, escorts, low bridges, etc etc.

[cjwirth]

Solar and wind energy will last no longer than the highways, which provide for their maintenance, as well as the maintenance of the power grid.

According to independent studies, global crude oil production peaked in 2008 and is now declining terminally.

Within a year or two, oil prices will skyrocket as supply falls below demand.

Independent studies indicate that global crude oil production is now declining from 74 million barrels per day to 60 million barrels per day by 2015. During the same time, demand will increase. Oil supplies will be even tighter for the U.S. As oil producing nations consume more and more oil domestically they will export less and less. Because demand is high in China, India, the Middle East, and other oil producing nations, once global oil production begins to decline, demand will always be higher than supply. And since the U.S. represents one fourth of global oil demand, whatever oil we conserve will be consumed elsewhere. Thus, conservation in the U.S. will not slow oil depletion rates significantly.

Alternatives will not even begin to fill the gap. There is no plan nor capital for a so-called electric economy. And most alternatives yield electric power, but we need liquid fuels for tractors/combines, 18 wheel trucks, trains, ships, and mining equipment. The independent scientists of the Energy Watch Group conclude in a 2007 report titled: ?Peak Oil Could Trigger Meltdown of Society:?

"By 2020, and even more by 2030, global oil supply will be dramatically lower. This will create a supply gap which can hardly be closed by growing contributions from other fossil, nuclear or alternative energy sources in this time frame."

With increasing costs for gasoline and diesel, along with declining taxes and declining gasoline tax revenues, states and local governments will eventually have to cut staff and curtail highway maintenance. Eventually, gasoline stations will close, and state and local highway workers won?t be able to get to work. We are facing the collapse of the highways that depend on diesel and gasoline powered trucks for bridge maintenance, culvert cleaning to avoid road washouts, snow plowing, and roadbed and surface repair. When the highways fail, so will the power grid, as highways carry the parts, large transformers, steel for pylons, and high tension cables from great distances. With the highways out, there will be no food coming from far away, and without the power grid virtually nothing modern works, including home heating, pumping of gasoline and diesel, airports, communications, water supply, waste water treatment, and automated building systems.

Documented here:
http://www.peakoilassociates.com/POAnalysis.html
http://survivingpeakoil.blogspot.com/

[galeso]

Certainly there is more oil and if motivated we could pump it out at a much faster rate. Perhaps, the demand at $4 per gallon is 20% less than it was at $2 per gallon. By 2020, and even more by 2030, global oil supply, make that demand will be lower due to higher prices including new taxes. Sure oil will not last forever, but some estimates put us at the half way mark, not running on empty as you suggest.

No, liquid fuels are not needed in the long term. In Chicago, the EL system and at least one full size train run on electricity.

Governments always find a way to raise revenue even if one source goes away.

Sure alternatives are now a tiny part of the total picture today, but if production of solar panels keeps increasing at 75% per year, in 13 to 15 years we will have 100% of our electricity coming from solar.

Do not believe everything you read.

[hollywoodsue]

Zoobie -

I'm doing some research on the coatings on wind turbines that prevent ice build-up, etc.
Can you contact me to share info about that??