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Wind Energy's Manufacturing Crunch
Wind turbine lead times are already measured in years not months
Joseph Ogando, Senior Editor -- Design News, September 17, 2008
In what has to be one of the biggest ironies surrounding alternative energy, many of the objections to wind energy focus on its effect on nature. Yet while the critics fret about the birds, the views and the noise, there's a much bigger barrier to wind on the horizon, one that many of its biggest proponents haven't yet taken into account. Wind energy, it seems, is starting to become a victim of its own success.
"The worldwide demand for wind energy equipment is outstripping supply," says John Dunlop, senior technical services engineer for the American Wind Energy Association (AWEA). The manufacturing base that produces the huge structural components, blades, generators and gearboxes that make up today's high-tech windmills simply can't keep up with the number of planned and ongoing installations. Dunlop points out wind turbines purchased today won't likely be delivered until 2011 or 2012. "That's the lead time right now," he says.
Those lead times are confirmed by key components suppliers too. "It's more like 2012 in most cases," says Parthiv Amin, president of Winergy Drive Systems, a subsidiary of Siemens Energy & Automation and maker of the gearboxes and power transmission components used in wind machines.
A sizeable chunk of this demand is coming from the U.S. AWEA figures put the annual growth rate of wind energy capacity in the U.S. at 29 percent for the five years ending in 2007. The association's projections show the U.S. installed capacity will increase from 17,000 MW at the end of 2007 to 25,000 MW by the end of this year. Germany, the current world leader in installed capacity, had 22,000 MW on line at the end of 2007. "As early as next year, we'll have once again taken the lead, which we had until 1997," Dunlop says.
And the growth taking place now is dwarfed by the growth that could take place in the coming decades. The U.S. Department of Energy this year released a technical report about a future in which we rely much more heavily on wind as a source for our electricity. Called 20% Wind Energy by 2030: Increasing Wind Energy's Contribution to U.S. Electricity Supply, the report forecast we'd need 300 gigawatts of wind-generated electricity to hit that 20 percent mark, up from about 1.5 percent today. Dunlop says the wind energy industry is already on track to meet that capacity increase, judging from the growth in 2007 and 2008.
Wind energy does have some adoption barriers unrelated to the supply chain for turbine components. For example, transporting and installing wind turbines that now routinely reach 100m and have rotor diameters ranging from 60m to 100m is one such barrier. So is power transmission over our existing grid infrastructure. "The windiest locations tend not to be located near our population centers," says Dunlop. And with wind, whose available energy is a function of wind-speed cubed, "location is everything," he says.
Yet the barriers that may matter most to engineers can be found in design departments and factory floors. In particular, Dunlop mentions a lack of wind-friendly gearboxes, generators and bearings as a current bottleneck that could affect wind energy growth in the short term.
That's not surprising. Wind turbine components have a lot more in common with aerospace components than industrial ones. Consider gear boxes, for example. Amin says a 1.5 MW wind turbine would have a gearbox that weighs about 16 tons with both planetary and helical stages. On a wind turbine, these gearboxes act to increase speed rather than reduce it. Amin says they typically take a 70 or 80 rotor rpm up to 1,400 rpm or so to run the generator. In short, these gearboxes have to be big and robust.
Yet they also have to be as lightweight as possible given the stresses they see, and they have to be more precise than many ordinary industrial gearboxes. "In the industrial world, you want a gearbox to be as robust as possible. You might have a 1.5 to 2.5 safety factor," Amin says. On a wind turbine, though, such a big safety factor would add up to unacceptable weight penalty that could propagate through the turbine design in the form of heavier tower sections, foundations and bearings. "We have to design to razor-thin factor of safety because the weight issue," he says.
The reduced safety factor obviously ups the ante on gearbox design and analysis as does the fact that these gearboxes sit in a nacelle that may be 100m off the ground, have limited maintenance opportunities and operate under variable load conditions. "Mother Nature doesn't provide the same amount of wind every day, and the location high up on a tower can produce all kinds of dynamic modal effects," says Amin. "There's a lot of design expertise involved that doesn't matter as much at ground level."
These gearboxes are likewise more difficult to manufacture than many small, industrial models. Winergy measures the tolerances for some of the mating surfaces, hole locations and gear faces in the ten thousandths of an inch and uses gears made to an AGMA Class 14 or 15. "Ours are very precise components, as precise as aerospace components, but much bigger," Amin says.
Many of the same design and manufacturing challenges likewise apply to bearings and generators, which also have to function in the same environment high off the ground.
So what do these supply chain issues for engineers and manufacturers mean? Dunlop believes the very same issues that pose a bottleneck today will ultimately create opportunities. He says by NAICS codes, "there are currently 16,000 manufacturing firms in the U.S. that could produce one or more of the 8,000-plus components that go into a wind turbine."
Of course, not all of those companies will be able to make it in the wind energy business. "Manufacturing wind turbine components isn't for everyone," Amin says. In fact, it may be just for companies with the most capable manufacturing systems. In the gear business, to take one example, profile grinding machines in producing large precision components have improved by "leaps and bounds" over the past few years to the point where it would be difficult to compete without a recent model, Amin says.
The same goes for composite blades. "You're starting to see some failures in the field," says Bill McCormick, business development specialist for composites at MAG Cincinnati Automation & Test. He attributes them not to design but to lack of automation still common in the production of the huge turbine blades. "There's still a lot of hand layup and eyeballing the placement of reinforcing layers," he says.
All that may change as more money flocks into wind energy. Amin says he's starting to see "tremendous investments" in the kind of advanced manufacturing capabilities needed to ease wind energy's supply chain bottleneck – perhaps as early as 2011 in his opinion. Winergy itself plans to invest $30 million in its Elgin, IL facility this year and another $70 million over the next four years. And Spain's Gamesa, a leading maker of wind turbines, has opened manufacturing plants in Pennsylvania to make blades, nacelles and towers.
Even as the manufacturing issues work themselves, wind energy will likely create some jobs for design engineers. Dunlop estimates the 20-percent electricity scenario would result in about 500,000 direct and indirect jobs, "many of them technical jobs." And some of that hiring has started to happen. Amin points to the hundreds or even thousands of engineering jobs currently available at the turbine OEM customers, other wind-energy component suppliers and their sub-suppliers. For engineers with the right skill set, including the ability to analyze precision power transmission and drive systems, wind energy promises to be more than a bunch of hot air.
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Wind Energy's Manufacturing Crunch
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I'm not 100% but I think the rotor speed in the article is off. At 70 rpm a 100M rotor would have a tip speed of 800 mph. I don't think they spin that fast.
chris greenwood - 2008-30-10 11:29:30 EDT -
The higher-precision and lower-weight gearbox issue begs the question: Can the rotational energy be transfterred from the top of tower to a base-mounted gearbox and generator via a shaft, or with hydraulics?
David Apfel - 2008-24-9 03:50:38 EDT -
PLEASE make those slides available in a LARGER size. They're just toooooo small to be useful on today's high resolution monitors.'>Excellent article. Thanks for drawing my attention to the report as well. I have long been an advocate of a diversified electric power system where wind plays a *part* in addition to nuclear, solar, etc... I am troubled by the T. Boone Pickens crowd who would have us believe that if we simply "did it", the turbines would practically build themselves. It's much more complicated than that.
PLEASE make those slides available in a LARGER size. They're just toooooo small to be useful on today's high resolution monitors.
Jeff Mizener - 2008-22-9 19:13:05 EDT
