Clean Power

Published on September 15th, 2015 | by William Steel


Siemens Looks Toward Next-Generation 10–20 MW Wind Turbines

September 15th, 2015 by  

Siemens has for some time been known to have its sights on developing the next generation of wind turbines — a class of platforms rated to 10 MW and above. But as a new manufacturing plant takes shape, the company’s management has begun speaking more openly on activities geared towards those objectives.

Die Prototyp-Anlage im dänischen Østerild wurde nur wenige Monate nach der Produktvorstellung auf der Messe EWEA Offshore errichtet. The prototype in Østerild, Denmark was installed only a few months after the product launch at EWEA Offshore trade show in Copenhagen.

Siemens recently signed off on a new German factory that will produce its flagship 7 MW offshore turbine. The new manufacturing plant is slated to begin production in mid-2017 and will be tasked with assembling generators, hubs, and nacelle backends together into complete nacelles — the working body of wind turbines to which blades are connected.

The factory will occupy 170,000 square meters at the North Sea port of Cuxhaven in northern Germany and employ some 1,000 personnel. The positioning of the factory is significant in its own right as placement by the port will allow large offshore components to be loaded directly onto vessels transporting the technologies, thereby reducing ground-transport costs of turbine components.

Investment in the factory is stated to be €200 million ($217.2 million). That investment, and plans for double-digit turbines are all part of Siemens’ push to lower the levelised cost of energy (LCOE) of offshore wind power, and achieve a one kilowatt hourly rate of 10 euro cents by 2020.

In an interview with Recharge, Siemens offshore wind chief executive Michael Hannibal explained how plans for the factory fit into a much broader, longer-term vision that his company holds for positioning itself as a key developer of next-generation wind turbines.

Although initially outfitted to assemble 7 MW turbines, the Cruxhaven plant will be built with the future in mind — able to switch, at some point, to assembly 10 MW turbines which the company revealed plans for last year.

That being the case, Hannibal also hinted to Recharge that, “We don’t call it a 10[MW development turbine], we call it a 1X[MW one], because we do not know how big that X will be.”

So, a flagship 7 MW turbine being assembled in a new manufacturing plant that’s capable of producing turbines of 10MW or more — it’s exciting news, but how does it fit into the landscape of ever-larger turbines, and why is it significant?

Let’s begin with the Siemens 7 MW turbine (technically the SWT-7.0-154), the company’s latest offshore wind turbine. Although it was only installed as a prototype at the Danish offshore wind National Test Centre in Østerild earlier this year, it’s already been selected for installation at several major offshore projects.

In itself, it’s a significant development in the evolution of wind turbines. Featuring Siemens’ “direct drive” technology, the SWT-7.0-154 is gearless — a technology that renders the turbine highly compact whilst reducing its mass. Indeed, the SWT-7.0-154 is the lightest turbine in its class.

Reducing turbine mass is an ever-present aspiration for wind turbine engineers, as it facilitates the ability to build taller wind turbines which are able to harness more powerful winds present at greater heights. By lowering mass, towers and foundations supporting nacelles may also be engineered using less steel, thereby saving on manufacturing costs. Lastly, direct-drive designs also reduce operation & maintenance (O&M) costs since gears represents a significant cause for failure and repairs.

The 7 MW model is pitched to yield some 10% more power than its 6 MW predecessor at comparable operational costs, producing 32 million kilowatt-hours of clean electricity under offshore wind conditions, enough energy to supply up to 7,000 households. It’s electrical output is in large part due to its huge rotor diameter of 154 meters.

(It ought to be noted that Siemen’s 7 MW machine is not the world’s largest turbine. That record goes to Vestas’ V164-8MW turbine.)

Vestas V164

Vestas V164-8MW turbine.

But while a 7 or 8 MW platform should be seen as advanced, it pales in comparison to Siemens’ vision to develop turbines rated at 10 MW and above. Last year, Recharge reported on those plans. Quoting Siemens Wind Power CEO, Markus Tacke, it wrote: “You look at the lifetime of our [nameplate capacity] platforms — 3.6MW becomes 4.0, then you move to 6.0 and upgrade that to 7-point-something [MW]. Another three to four years and you need the next product.”

By those indications, and with the latest information, we should expect that, by 2020, we will see the introduction of 10 MW platforms, predicted to have a rotor diameter greater than 200 meters.

Siemens is already a leader in European offshore wind power with a 86.2% market share of connected MW at the end of 2014. It has some 1,470 turbines installed in waters around the world, reaching a combined capacity of 4.7 GW. Considering the development trajectory it’s laying groundwork for, it’s plain to see that the company intends to retain its leading role in the industry.

Industry projections may produce upper limits on turbine height and size, but these certainly won’t be reached before the end of the next decade. In the meantime, therefore, expect to see larger, more powerful turbines being introduced and the costs of electricity derived from wind power fall yet further as a consequence.

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  • Jens Stubbe

    “achieve a one kilowatt hourly rate of 10 euro cents by 2020.” Why the sudden increase? Should they not aim at reducing offshore wind power cost???

    The latest auction at Hornsrev 3 was won at a FIT at 0,77/DKK 50.000 full load hours, which assuming 25 year lifetime and current Nordpool for the period after the FIT expires is well below the €0,10/kWh goal stated in the article.

    The new right wing government in Denmark has just slashed a number of projects that targeted a significantly lower FIT that was also much fewer full load hours.

    The industry is foolish if they honestly believe they can sell projects in the future that even with the poor north European insolation could be made cheaper with solar.

    And quite frankly I do not understand why Cleantechnica reports this without digging deeper and asking the critical questions.

    • Bob_Wallace

      Offshore for 12 cents US? That’s a produced cost, no subsidies?

      • Jens Stubbe

        Bob the auction was for a FIT covering 50.000 hours to the winning consortium that in return builds, owns and manages Hornsrev 3 and it was won at DKK 0,77/kWh. Horns Rev 3 is connected to the grid from the transformer station at the expense of Energinet, which is a government owned company that regulate and run the grid.

        Vattenfall won and has chosen Vestas and most likely the new 8MW turbine.

        The other coast near offshore projects that the new right wing government has decided to slash had a fixed FIT at DKK 0,60/kWh but only for about 30.000 hours.

        The FIT rules also stipulates that the turbines will be curtailed whenever the energy price at Nordpool is negative.

        Offshore for 12 cents US – never again – that is far and beyond the real market price.

        The actual produced cost with no subsidies will of cause be much lower than the FIT at DKK 0.77/kWh and especially so because after the FIT period the consortium will sell exclusively to the current market price at Nordpool. My guess is that when the 25 year lifetime is completed the average selling price per kWh will be around 6 cents US and that the production price will be still lower to allow the consortium a healthy profit. The institutional investors that eventually comes with the money are typically pension funds that are looking for stable investments that deliver better than average return on investment.

        The upcoming tender at Kriegers Flak has so far 8 consortia competing and the expectation it will be won at a lower bid than Hornsrev 3 as there is over capacity in the offshore value chain and a rush of competitors that challenge Siemens and Vestas.

        Because I know you take great care to have your facts in order I have found information about the above but to read it and the comments you have to use google translate.

  • Shiggity

    Whenever you guys see a group of turbines with a capacity factor over 50%, that group is no longer an intermittant resource.

    This principle is something that the anti-wind people either do not understand or refuse to admit.

    Pretty much all new direct drive turbines are either close to 50% capacity factor or above.

    • Bob_Wallace

      What would be really helpful is knowing the number of hours (percentage of hours) that the wind farm was producing significant electricity.

      It’s very common to encounter people who believe that a CF of 40% means that the wind blows only 40% of the time.

      • Ivor O’Connor

        So what does it really mean?

        • Bob_Wallace

          CF = actual power produced / theoretical maximum production

          • Ivor O’Connor

            So you are saying that 40% usually means the turbine could be blowing all of the time but only at 40% of it’s max.

          • Bob_Wallace

            Sure. But that’s a very unlikely situation. If the turbine never exceeds 40% rated output then there’s a problem with the tower being too short or the blades too small.

          • eveee

            There is an energy duration curve. It shows the number of hours at each output. From that one can predict the output probabilistically.


            At highest capacity factors the curve shifts up and to the right. The left side may decrease.

          • Ivor O’Connor

            It doesn’t shift up and to the right though. I tried to google “energy duration curve” and see many references to “flow duration curves” but not energy duration curves. Have you got a link to help explain these curves?

          • eveee

            In the graph, the single turbine curve will have less time at high capacity and more down time than the average of all Nordic turbines over a wide area. The y-axis of the graph is % of capacity, and the x-axis is hours.

            So reading the blue curve for example, we read about 5000 hours at greater than 20% capacity. The 8760 hours at the max is the annual max hours, 365 x 24 = 8760.

            Note in the blue curve that there are still over 8000 hours at 10% capacity. 91.3% of the time, wind produces more than 10% of rated capacity across the Nordic system.

            So note that the blue curve falls on the left, and rises on the right, implying its higher availability. The single turbine curve does the opposite, rising on the left, and falling on the right.

            It because of the shift in number of hours.

            The single turbine is frequently running at lower relative output compared to the system as a whole spread over a large area.

        • Omega Centauri

          a CF of 40% could mean it runs 40% of the time at max output, and 60% at zero, Or 100% of the time at 40% output. It really is only the integral of the distribution, it doesn’t say much about how much it varies.

          • Ivor O’Connor

            Thanks OC. I wonder if turbines are fine tuned for the wind speeds they are likely to encounter. Or if it normally blows at 13 mph every day, 24×7, that you might only get at most a CF of 30%.

          • Bob_Wallace

            Turbines are definitely designed and fine tuned for their specific locations. We saw a significant jump in CF once the industry grew to the point at which it was financially possible to build different models, blade size/characteristics, etc.

            Test equipment is generally put into place well before the wind farm is built so that data can be gathered for the specific site. Right now there are a couple of data gathering vessels off the coast of Oregon collecting data on PNW offshore wind.

          • Ivor O’Connor

            That’s fascinating. I suppose there is an industry built up on how to monitor. Not just prior for perhaps a year but ongoing too. And perhaps staged roll-out planning. These topics would make great articles.

          • Omega Centauri

            I don’t know if I’d call that fine tuning. WT farm developers have a selection of turbines to choose from, and based upon the measured wind distribution at the site will select the turbine with
            the best economics.

          • Bob_Wallace

            OK, semi-fine tuning.

            Add in some blade selection. And likely some software adjustments.

          • eveee

            The same CF could produce different energy duration curves.

            Theoretically you could get some better information about probabilities from a curve like this.


      • Ronald Brakels

        In Australia wind availability tends to be about 80+%. That is, wind turbines tend to produce at least some electricity 80% or more of the time.

        • Steven F

          In the wind industry Availability typically means the percentage of time that the turbine is available to generate power. it is mainly a measure of wind turbine mechanical reliability. Not power generation. Most turbines around the world have an availability of 80% or greater (+90% is quite common).

          Capacity factor is a measure of how much power a wind turbine actually generates compared to an theoretical turbine that generates maximum power every hour of every day of the year. While the newest turbines have a CF rating of 50% . Most older turbines are at about 35%. Capacity factor is strongly influenced by how often and how strongly the wind blows. Capacity factor often changes from year to year due to variations in the weather that year. According to this Wikipedia article Australian wind turbines average a capacity factor of 30 to 35%.

          For example a wind turbine suffers a failure and due to various issues it take 1/2 a year to repair. That turbine would have an availability of 50% A second turbine nearby during that same year has no mechanical issues for the entire year. That second turbine would then have an availability of 100% Then let us assume that both turbines were fully functional when the wind was blowing that year(highly unlikely in this scenario but still possible). Then in that case both wind turbines would have the same capacity factor for that year and would generate the same amount of power.

          • Bob_Wallace

            Steven, I don’t think you paid attention to what Ronald posted.

            “some electricity 80% or more of the time.”

            That’s a different sort of availability than the percentage of time the turbine is in operating condition (I’ve seen that run to 98%).

            Look at this data from Danish wind farms. There’s “some wind” a high percentage of the time.

    • Ivor O’Connor

      Seems a pretty arbitrary definition. Why would anybody call something that produces with a CF of over 50% non-intermittant. And what would that term be? Perhaps “permenant”?

      • heinbloed

        “mostly permanent” 🙂

  • Richard Foster

    2 key questions in my mind –
    1. Do bigger turbines result in bigger CFs – I.e. can we get more generation from the same sites
    2. Do the bigger turbines work better in higher and particularly lower wind speeds? If we want wind power to provide 40-50% globally, operation at low wind (and generating significant amounts at low wind) is key

    • JamesWimberley

      IIRC the resource goes up with height because of wind shear, which isn’t much above 100m. The weather component won’t change. So the cfs should stay much the same. I assume that by now the designers have fully optimised the designs for the wind régime and a flat FIT. A shift to a duration-based payment would change the rules of the game again, but nobody influential seems to be talking of this yet. Would it really be better value to increase wind cfs, at some cost in total annual output, or to pay for despatchable backup?

      My pet theory for the observed rise in cfs without any duration incentives is that it’s a rational engineering response to taller hubs. Maximum power is proportional to peak rating and thus the weight of the nacelle. Rotors are light, so tower cost goes up much more with nacelle weight than rotor diameter. Hence i pays to increase the ratio of swept area to generator rating, leading to lower peak output and a higher cf.

      • Richard Foster

        Hmm I think I follow that. Need to think about it a bit more.

        BTW – I remember you discussed this the other week:

      • Ivor O’Connor

        Seems without the shear you’d have more of a chance of reaching the minimum wind speed needed. More operational time means greater CF right?

      • eveee

        About right. There is some need to increase tower strength due to side loads from increased rotor diameter.

        And increases in wind speed at height do lead to increase power output because the most important factor of all is power is proportional to wind speed cubed.

        140m wind data is now revealed by NREL. The result – capacity factors rise and wind could replace coal.

      • Jens Stubbe

        Hi James what you require has been implemented in Denmark where you curtail wind power even in the FIT period if the price of electricity becomes negative.

        Besides wind turbines in Denmark operates on pure market terms for at least 60% of their lifetime so the owners of the wind turbines explicitly demand higher CF’s to optimize the market value of the electricity production.

        I would expect owners of wind turbines to curtail production at times where the market price does not cover the expected cost associated with production.

        Taller hubs does not make sense offshore as the wind shear factor at sea is without much relevance in lighter winds and completely irrelevant once you operate above the rated power. All offshore turbines are designed with a hub height that ensures that the blades just go clear even in rough weather conditions and nothing more.

    • Ulenspiegel

      In contrast to onshore, the price of the turbine is in case of offshore wind not the factore, logistics is. Reducing the number of turbines is therefore a good strategy even without more kwh per kw.

      • eveee

        Yes. Logisitics and foundation. The turbine is not the largest factor.
        Each foundation has to use the maximum number of khwrs generation to lower cost. Thus the push to the largest turbines possible.

  • NicholB

    Great how these things keep growing. If the turbine factory has to be positioned at the sea, is the conclusion that offshore wind turbines are growing to a scale that will not anymore be deployable in most onshore locations? Wind energy may be evolving into two totally separated species.

    • nakedChimp

      Maybe more to do with most places you can site a 7MW+ turbine being in NON-NIMBY land, ie. offshore.. but as can be witnessed in England even that is not sure.

      To bad that cargo-lifter thing never made it.. would had been cool to see big blimps delivering heavy wind turbines all over the world 😉

    • jeffhre

      Hard to trailer a 7MW turbine, nacelle and 154 meter rotors under local bridges!

  • JamesWimberley

    There isn’t a single statement from Siemens reported in the post that suggests they are looking at 20 MW. All we have is:
    “We don’t call it a 10[MW development turbine], we call it a 1X[MW one], because we do not know how big that X will be.” The historical trajectory of increases clearly suggests that X will be low, perhaps 11 or 12 MW. The caution is necessitated by the inherent diseconomies of scale in towers. Power goes up with swept area, a 2-dimensional ratio (r squared). Tower mass goes up in a a 3-dimensional ratio (something cubed). Going bigger depends on improvements in tower design.

    • nakedChimp

      They’re talking steel there.. any idea if they’re considering some sort of fiber (carbon, etc.) to get the strength they need?

      • Jan Veselý

        They use carbon fiber for blades just because of weight. You know, lighter blades (and no gearbox) means lighter tower, less steel, lower cost and no rust. And not forget that Siemens have its stake in carbon fiber research. If they will be able to cut the cost of CFRP to 2USD/kg, it is game over for steel. Steel costs about 0.4-0.5 USD/kg but you need 8-10x more weight to have the same mechanical performance.

      • eveee

        Discussions of concrete. There are tall towers even constructed of wood in Germany. And there are new construction techniques. GE has a lattice design.

        Transport cost is the key issue on land.

    • Jan Veselý

      I’m dreaming about lightweight carbon fiber 3D printed towers using f.e. honeycomb design to be stiff and light. You just come to a place with ready foundations, unload a truck with robotic printer and you just keep bringing “printer filling”.

      • heinbloed

        This is how concrete towers are casted, in-situ and in an ‘climbing’ shutter.

    • Ivor O’Connor

      Maybe we need some articles on tower design…

    • Jens Stubbe

      Please explain why you feel tower mass will be cubed with increased height. Are you really implying that a doubling of the height of a tower will cause a cubed weight increase?

      There are many tower designs that are significantly higher than the industry standard solutions and at the same time are lighter. It is just a matter of time before such designs achieve market traction.

    • jeffhre

      11 or 12 MW = low trajectory LOL!

      Gotta keep things in perspective there. The worlds largest is only 8 MW! And terrestrially most of the Gamesa and GEs are 2 MW. And 2 MW equal to or less than totality of the low trajectory from Siemen’s largest 7 GW turbines now – 7 GW to 12 GW is a hefty increase. No?

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