Wind Turbines Shed Their Gears

[madokie]

http://www.technologyreview.com/energy/25188/

Both Siemens and GE bet on direct-drive generators.

By Peter Fairley


Tuesday, April 27, 2010



Wind turbine manufacturers are turning away from the industry-standard gearboxes and generators in a bid to boost the reliability and reduce the cost of wind power.
Power ring: This three-megawatt wind turbine uses permanent magnets and a design that makes it significantly lighter than a conventional geared turbine.
Credit: Siemens

Siemens has begun selling a three-megawatt turbine using a so-called direct-drive system that replaces the conventional high-speed generator with a low-speed generator that eliminates the need for a gearbox. And last month, General Electric announced an investment of 340 million euros in manufacturing facilities to build its own four-megawatt direct-drive turbines for offshore wind farms.

Most observers say the industry's shift to direct-drive is a response to highly publicized gearbox failures. But Henrik Stiesdal, chief technology officer of Siemens's wind power unit, says that gearbox problems are overblown. He says Siemens is adopting direct-drive as a means of generating more energy at lower cost. "Turbines can be made more competitive through direct-drive," says Stiesdal.

Siemens's plans hinge on a new design that reduces the weight of the system's generator. In conventional wind turbines, the gearbox increases the speed of the wind-driven rotor several hundred fold, which radically reduces the size of the generator required. Direct-drive generators operate at the same speed as the turbine's blades and must therefore be much bigger--over four meters in diameter for Siemens's three-megawatt turbine. Yet Siemens claims that the turbine's entire nacelle weighs just 73 metric tons--12 tons less than that on its less powerful, gear-driven 2.3-megawatt turbines

[Go2Peace]

1. Sorry, according to the industry experts here only "Nucular" is a true alternative energy

Just kidding. Good news. Wind won't solve all of our needs, but it will be a big part of the mix.

[joshcryer]

2. You will not find more than one person on this forum who would agree with that statement.

I know you are joking but the vast majority of nuclear "supporters" on this sub forum are pro-renewables.

[madokie]

4. I don't pay that much attention anymore

but there have been those who were just as was stated. I have noticed that, for the most part, the pro-nuke crowd will put a dig in when ever alternates are mentioned. Saying it ain't so does not the truth make. :hi:

[AtheistCrusader]

6. And here we have a renewables thread where the first reply is a dig on Nuclear.

Two, tango, etc.

I'm extremely pro-nuke, but I'm also very pro wind, PV, concentrating solar, and hydro-electric.

[joshcryer]

20. It is mostly a reaction to the heavily anti-nuclear power sentiment expressed by a handful...

...of posters here. Believe me, the vast vast majority of pro-nuclear power posters on this forum are pro-renewable. Strongly so.

[joshcryer]

3. As I read the article I got to thinking about REEs, the comment section there discusses it too.

We need to start researching magnets that aren't REEs.

[Statistical]

5. Rare earth elements are going to be major problem in coming decades

IIRC 90% of the worlds supply is in China and China has already placed export restrictions on them.

It isn't just turbines but electric motors, hydrogen storage, high density batteries, lasers, high temperature capacitors, high temp super conductors, some semi-conductors, etc.

That is a ingredient list for any low carbon economy.

[kristopher]

7. No they are not.

The current supply is sourced primarily in China for the same reason manufacturing is - it's cheaper. A small marginal increase in the price of these COMMON commodities means expansion of operations in any of the many, many other places possible, nothing more.

It is amazing how you understand this when you want to convince people we have an unlimited supply of uranium, but your intelligence totally fails you when you are attempting to discredit renewable energy.

[Statistical]

8. Nobody said unlimited supply of uranium and nobody said US has no ree.

Supply of rare earth elements is large but it isn't geographically uniform.
Just like any resource there are "rich" countries and poor countries. US is coal rich and oil poor.
Total amount of oil in the world is less relevant to US energy security as US oil consumption and local supply.

US is moderately uranium rich while India is uranium poor.

The issue is more complex then total global resources.

Obviously even DOD is concerned about supply implications:
http://www.technewsdaily.com/us-military-supply-of-rare-earth-elements-not-secure-0430/

USGS Survey puts US reserves of rare earth elements at a tiny fraction of global supply
http://minerals.usgs.gov/minerals/pubs/commodity/rare_earths/mcs-2010-raree.pdf

Even worse not all rare earth elements are formed in same deposit. Heavy Rares (atomic number 64 and higher) tend to be even less abundant in US geology.

When you have a very energy hungry population that presents a concern.

[kristopher]

11. Bull.

Rare earth elements are not rare; they are some of the most abundant elements on the planet. Their distribution is not concentrated in any way that would allow any type of cartel to bottleneck supplies. You are just stoking yet another rightwing, antirenewable energy meme.

[joshcryer]

13. You clearly do not understand my comments about REE.

I was not making the canned "REEs are too rare and difficult to mine" but rather "production of REEs cannot meet the needed demand for wind, therefore we need non REE PMs to grow wind as quickly as possible."

You of course live in denial, and project what you want on to others, rather than trying to actually have a discussion.

[tiptoe]

17. .. nt

[joshcryer]

15. It only presents a concern if there are no alternatives, imo.

Since turbines don't need REEs then I feel we should use the path of least resistance with minerals that can be produced more efficiently and cheaply.

[Statistical]

16. 28 years after the discovery of Neodymium by General Motors

Nobody has discovered a substitute as effective.

Sure you can make electric motors for example without Neodymium but they simply won't last as long, weigh as little, and provide same level of output to weight that current high amp Neodymium driven motors do.

[Statistical]

18. Correction i meant to say 28 years after discovery of Neodymium magnet application n/t

[joshcryer]

19. Jacobson covers alternative technology paths that are "just as good."

From "Evaluating the Feasibility of Meeting all Global Energy Needs with Wind, Water, and Solar Power," draft.

There are at least three kinds of alternatives:

i) generators that perform at least as well as PM generators but don’t have scarce REEs;

ii) generators that don’t have REEs but have higher mass per unit of power than do PM generators (the greater mass will require greater structural support if the generator is in the tower); and

iii) generators that have higher mass but are placed on the ground (this eliminates the need for extra structure to support the generator, but requires redesign of the whole turbine system).


Morcos (2009) presents the most cogent summary of the implications of any limitation in the supply of Nd for permanent magnets:

A possible dwindling of the permanent magnet supply caused by the wind turbine market will be self-limiting for the following reasons: large electric generators can employ a wide variety of magnetic circuit topologies, such as surface permanent magnet, interior permanent magnet, wound field, switched reluctance, induction and combinations of any of the above. All of these designs employ large amounts of iron (typically in the form of silicon steel) and copper wire, but not all require permanent magnets. Electric generator manufacturers will pursue parallel design and development paths to hedge against raw material pricing, with certain designs making the best economic sense depending upon the pricing of copper, steel and permanent magnets. Considering the recent volatility of sintered NdFeB pricing, there will be a strong economic motivation to develop generator designs either avoiding permanent magnets or using ferrite magnets with much lower and more stable pricing than NdFeB.

Incidentally I have my own 100+ kW design that employs the third option, putting the generator on the ground (and presumably using a shaft to drive it). Hopefully one day I'll build it.

[joshcryer]

12. Nd used in magnets for wind turbines *cannot concievably grow to avert catastrophic climate change.*

The global Nd reserve or resource base could support 122,000 metric tonnes of Nd oxide production per year (the amount needed for wind generators in our scenario, plus the amount needed to supply other demand in 2008) for at least 100 years, and perhaps for several hundred years, depending on whether one considers the known global economically available reserves or the more speculative potential global resource (Table 4). Thus, if Nd is to be used beyond a few hundred years, it will have to be recycled from magnet scrap, a possibility that has been demonstrated (Takeda et al., 2006; Horikawa et al., 2006), albeit at unknown cost.

However, even if the resource base and recycling could sustain high levels of Nd use indefinitely, it is not likely that actual global production will be able to increase by a factor of five for many years, because of political or environmental limitations on expanding supply. Therefore, it seems likely that a rapid global expansion of wind power will require many generators that do not use Nd (or other REE) PMs.

From "Evaluating the Feasibility of Meeting all Global Energy Needs with Wind, Water, and Solar Power," draft.

[AtheistCrusader]

21. Please link to a post where someone claims we have unlimited uranium?

USGS has indicated 3.1 million metric tons of reasonably assured resources for Uranium around the world. That's not 'unlimited', but it is quite a lot.

[kristopher]

22. Google DU for uranium and seawater

[joshcryer]

14. The key here is that turbines have alternatives, PV engines, electronics, etc...

...not so much.

[FBaggins]

9. This should cut down on the incidence of turbine failure

Don't the most spectacular failures tend to involve a gearbox problem?

[Statistical]

10. Usually.

The gearbox is most complicated portion of the system and under a lot of pressure and cooled by oil.

I had posted this a graphic a while back GE 4MW turbine with no gearbox.