Wind energy has hit a snag. The companies involved can't make the turbines fast enough.
"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.Wind turbine manufacture is hard to ramp up because the parts are very hard to make.
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.
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.And it is not just gear boxes. The blades are difficult to make too.
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 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.Imagine trying to make a 150 ft. long blade by hand placing fiberglass. It would be hard to keep acceptable tolerances. And as the turbines get bigger fiberglass won't be strong enough. Carbon fiber will be required. And ordinary copper and steel generators will get too heavy. Superconductors will be required.
However, for immediate manufacturing problems hope and help is on the way.
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.Elgin is about an hour's drive from where I live. I probably should take a camera and visit the plant some day.