The Innovation Quandary For Operators:
When does reducing risk require taking risk?

Reprinted with permission from North American Windpower, June 2006 issue.

By Peter J. Kunz & Daren F. Gretz, TF Energy Group

Only a few months ago, in the grand ballroom of a New York hotel, a venture capital financier stood up to make a presentation on the investment potential of renewable energy – specifically the wind industry. Glancing at the audience, he noticed every seat occupied and every eye riveted…and couldn't resist a wry reminiscence: "Back when I made my first presentation on wind energy," he said, "there were only 10 guys with ponytails in the room."

Yes, times certainly have changed.

This summer, as the nation's largely fossil fuel-based energy portfolio comes under increasing stress, as geologists debate the inevitable peak in world oil production (when demand will permanently overtake discovery and supply) and as the American president (himself a former oil man) calls upon wind energy to provide 20% of the nation's power by the year 2020, it would seem the industry's day in the sun has finally arrived.

Public acceptance has gained traction, if not quite a wholehearted embrace. Last year saw an end to the usual Congressional foot-dragging on wind energy production credits. And installations are on pace for another record year. To paraphrase the infamous movie line, suddenly "green is good."

But for many individual operators, significant technical risk issues remain – not least the questions of grid integration and power forecasting. In other words, your ability to consistently deliver the goods.

The question is: Can today's maturing turbine technology and control systems provide the operational reliability and cost-of-energy competitiveness to secure a significant, enduring position on the nation's electrical grids?

Experts say the answer is yes.

But in this article we'll look at important recent advancements in wind turbine gearbox technology, lightning protection and forecasting models from the standpoint of how they can dramatically improve grid integration, cutting the cost of energy production and, crucially, reducing operators' exposure to loss – not at some distant point in a theoretical future, but very soon, and in some cases right now.

From a perspective of managed risk for large-scale operators, all these benefits work hand-in-glove. Greater reliability translates into less down time, lower maintenance and repair costs, and reduced risk financing (insurance) costs. Ultimately, this means a significant reduction in an operator's total cost of risk. The bottom line is lower cost of energy, greater competitiveness and enhanced profitability.

We have the technology

From his headquarters in Golden, Colo., Sandy Butterfield has a comprehensive and (by all accounts) unbiased view on the state-of-the-art wind turbine technologies. He is chief engineer for the government's National Renewable Energy Laboratory, where he is deeply involved in several pioneering programs at various test sites.

In an interview, Butterfield was measured but unequivocal in his enthusiasm for wind energy's near future – at least from the technical side.

"If the political will is there," he says, "we do have the technology and the power electronics to coordinate and manage as much as 20 percent of the nation's power supply [within a decade or so]…the technology is there."

"Specifically, in terms of meeting the Department of Energy's goal of 3.6 cents/kWh by the year 2012, at least three machines [turbines] are right on track to meet or exceed that," Butterfield says.

By name, he cites the 3.0-MW V-90 by Vestas, the Siemens 90-meter Goliath and Clipper Windpower's 2.5- MW Liberty turbine. These turbines are either now entering the market or in the last stage of testing. They all feature a number of operational-risk-reducing innovations in blade and nacelle design, and even built-in cranes for easier service.

In the last decade, as turbine size has scaled up to a point where threeblade rotors now rival the wingspan of a Boeing 747, gearbox and drive train failures have plagued operators, often at crippling costs (as much as $300,000/gearbox failure).

One recent published report says retrofits of gearbox bearings were necessary at all 30 turbines of an offshore operation – after less than two years. In another case, many turbines were already on their second and third gearbox retrofit after only five years.

Most engineers think the problem is endemic. Generally speaking, power production increases exponentially with blade length. But larger, slower- turning blades also deliver exponentially more torque to a gearbox, subjecting conventional mechanisms (conceived in an earlier generation) to extreme stress and wear on bearings and gear teeth.

When a turbine trips offline from gearbox failure, this also trips a cascade of risk consequences, beginning with down time and repair and culminating in increased risk financing costs. Industry-wide gearbox failurerates have been the subject of many managed risk initiatives.

As manufacturers vie for supremacy in next-generation turbine technology, gearboxes and drive trains have been focal points of intense research and development, with encouraging results. A number of concepts are in the works, including a direct-drive system that eliminates the gearbox entirely, while multi-stage gearboxes still dominate the market.

But "silver bullet" solutions can be expensive. Owners and operators who already are heavily invested in their existing (if at times costly and troublesome) technology can be leery of "prototypes." This goes for underwriters, too.

"The truth is, the conventional turbine gearbox has been 'broke' for a long time," says Mary McCann- Gates, a 25-year wind industry veteran and communications director for Clipper Windpower in California.

So, in developing its fourth generation turbine, the Liberty, Clipper focused on this critical element…and went back to the drawing board.

"We asked: What does every operator want?" says McCann-Gates. "What they want is no down time. Better performance and bigger blades mean nothing when a machine isn't online."

For the new 2.5-MW Liberty turbine, Clipper created a low-rpm, high-torque gearbox that distributes the stress-load to second-stage gear sets and drives. Four high-speed output shafts disperse the load by a factor of 16 – or 400% more than conventional gearboxes. And like a four-engine 747 that will continue flying even if an engine goes out, Liberty is equipped with four permanent magnet generators for operational redundancy - if one fails, Liberty operates until repairs can be made.

During a visit to Liberty's test bed in Medicine Bow, Wyo., the risk-reducing innovations were noted, including a built-in condition monitoring system and a utility disturbance ride-through capability of up to 3 seconds without faulting, exceeding industry standards of 150 milliseconds.

Certainly no one claims the Liberty, slated for serial production of 100 units this year, is fail-safe. But this turbine is certified for a 30-year service life – a confident statement on the part of the manufacturer.

Advancements in damage control

The indefatigable enemy of all wind operators is lightning. Some studies indicate damage from lightning strikes may be the single greatest source of down time. Experts caution it's not that simple – variances in terrain are a critical factor.Wind operations in California, for example, historically do not sustain the volume and severity of strikes as seen in midwestern or southwestern areas.

But for the industry as a whole, particularly as expansion reaches further into the wind-fertile Heartland regions, the anecdotal evidence is undeniable.

In one study of a large-scale southwestern operation, lightning-related damage (to blades, generators, controllers, etc.) caused 85% of down time. At another site, damage exceeded $250,000 in the first year. Hastily installed, retro-fitted protection systems proved to be of little help.

In northern Europe, analysis of more than 11,000 turbine-years found lightning was the number-one source of all outages, even exceeding turbine mechanical breakdowns. One utility in Germany was forced to shut down and dismantle after it was de- nied insurance for any further lightning damage.

Over the years, turbine and blade manufacturers have developed a range of increasingly sophisticated composite materials and receptorconducting systems to combat lightning strikes, with varying degrees of effectiveness. Now comes an approach inspired by the aviation industry.

LM Glasfiber is equipping its 61.5P turbine blades with custom "diverter strips" of the type used to protect radar domes mounted on an aircraft. The strips (narrow bands in the blade structure to which tiny pieces of metal are fitted) are designed to channel lightning to a receptor and safely away from the blade surface.

Unlike aviation diverter strips, which must be replaced frequently, LM says it has modified the design to match the typical 20-year service life of most turbines. They may also be retro-fitted.

Again, diverter strips are not to be mistaken for silver bullets. And lightning strikes can no more be prevented than wind can be summoned on demand. The biggest source of lightning- related damage, in fact, is not directly related to blades or turbines, experts say, but in power surges to the controllers – effectively halting operations.

"It's a question of 'damage control,'" one engineer says "and if more operators simply followed the standard guidelines, they could dramatically - dramatically – reduce their risk of damage."

What guidelines? Actually, there's an excellent document available to any operator. Go to www.iec.ch - Web site of the International Electrotechnical Commission, a Genevabased organization of engineers and scientists.

Forecasting

Earlier we asked rhetorically – in terms of grid requirements – if wind power can consistently deliver the goods. In an industry that relies on an intermittent power source, predictive models are a key.

Butterfield, the NREL chief engineer, relates to this anecdote.

"A couple of years ago I was driving through a hellacious lightning storm on my way to Chicago – and it was July 4th, so I remembered the date," he says. "About four months later I saw a presentation by a company called Wind- Logics (out of St. Paul, Minn.), and it turned out they had the precise wind profiles for that same storm."

"The state of the art in this area really impressed me," Butterfield says.

Wind mapping (for site locations) and atmospheric modeling by firms, such as WindLogics and AWS Truewind, Albany, N.Y., has progressed to a point where, coordinating via today's power electronics, operators can predict their output not just hour-byhour but often second-to-second – a critical step in transforming wind from an alternative to a predictable and substantial provider in terms of grid requirements.

Some industry analysts have said that "all the big breakthroughs have been made" in terms of wind technology - now it's only a matter of tinkering, tweaking and improving the applications. But try telling that to an operator whose annual operating revenues have just been wiped out by another busted gearbox.

Innovation must continue, with imagination as a necessary partner.We are reminded by the consulting guru Geoffrey Moore, among many others, that innovation itself isn't usually the hard part. To devise a Phillips screw or a pop-top can require a leap of insight - but not jumping through a series of administrative hoops.

What's often proven more difficult is "deploying that innovation in an established enterprise or existing market," Moore says. Why? "Because established operators can't [give their full attention] to 'unproven' technologies when their current ones are already hanging by a thread," he adds.

One might add that "selling" underwriters on new technologies isn't a slam-dunk either. As one analyst told us: "everybody wants to stay with 'what works' – even if it only works 70 percent or 80 percent of the time."

Butterfield recommends that operators and their insurers get more involved, and sooner, in the process of invention, testing and certification.

"If everyone in the industry would get more involved [earlier in the testing], visit the sites, come to the workshops, see the extensive, detailed and very rigorous certification processes," it would serve everyone's best interests in managing the inherent risk of innovation.