The Power Pendulum


February 14, 2012

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Engineering is usually seen as crucial to ensure offshore wind farm success. But should software not be just as important as hardware in the long term?

By Jason Deign, European Correspondent

Scan any edition of A Word About Wind and it is pretty evident that engineering is at the heart of the wind energy business. Deals are won or lost on the strength of turbine designs. Projects stand or fall on the reliability of their machinery. Yet it is also true that the margin for innovation in engineering is getting smaller. Turbines have grown immensely in size over the last two decades, but have not changed significantly in form.

Even in offshore wind, where there are unprecedented challenges in terms of scale and environmental stress, the preference is for still for traditional horizontal axis designs. Today’s turbine research and development efforts are largely focused on incremental improvements on this basic design. By looking at new materials to handle the stresses in longer blades, for instance, or by experimenting with the concept of magnetic drive. And while these efforts can to some extent assist, increasingly they’re creating something of a problem for the industry.

Dr Pascal Storck, chief operating officer at 3TIER

Pascal Stork

In short, the incremental improvement approach increases the chances of different engineering teams converging on what is essentially the same design. At the same time, the potential for new breakthroughs is diminishing because large engineering firms now dominate practically all turbine manufacturing, whereas innovation is typically greatest in small, independently minded teams.

This situation will be familiar to anyone who has ever wondered why modern cars all look the same. Corporately sponsored incremental engineering is great for perfecting existing designs, not creating new ones. If that is the case, the European wind industry may need to start looking elsewhere for step changes in operational improvement. And a good place to start would be better estimates of how wind variability will impact production over the life of a project.

It is undoubtedly true that even the best turbine design is worthless without wind to power it. Yet despite advances in turbine technology, the methods many project developers and their investors use to estimate how much power – and thus revenue – their projects will produce have advanced very little in the modern wind energy era. Projects are frequently seen to deliver less than they were designed for, according to Dr Pascal Storck, chief operating officer of 3TIER, a renewable energy risk analysis company.

“We consistently see customers who have built a wind farm expecting, say, a 35% long-term capacity factor, and are getting less than what they hoped for,” he says. There can be two reasons for this, but the root cause of both is simple: lack of accurate information about the wind resource at the site.

According to Storck, much wind farm planning currently follows a “hunt and peck” process: developers find what looks like a promising site, get some basic wind data together and then try to extrapolate it over the life of the project. Then they get building. Such an approach has two risks.

“First, your basic data set may not fully reflect the characteristics of the site,” says Storck. “The air speed you get from ground- or sea-level anemometer might have nothing to do with what you get around a hub 143 metres up or across varied terrain.”

Second, and more importantly since wind farm planners are less likely to take this into account, measurements taken over a year or two may fail miserably to give you a true picture of the long-term wind variability. And trying to correlate that data to data from a remote, long-term reference site can introduce still more uncertainty into the equation.

“Wind farm business plans are typically built around what are deemed to be ‘average’ weather conditions, but in fact there is no such thing as average weather,” Storck says. “The only thing you have is degrees of variability.” Consider, he proposes, that your site survey shows a mean wind speed of eight metres per second. That sounds great. However, “what you may not know is that the region you are looking at has practically no wind for six months of the year, or that weather patterns vary over a three to six year cycle.”

European wind speed variance from average (2011), courtesy of 3TIER

3TIER 2011 emea comb variance

Of course, the beauty of an average is that you should have equal chances of coming in above it as you do below. That is fine if you do not mind taking on the odds; but for most wind farms, overestimating wind potential can have a more profound impact on the business plan than any engineering glitch.

To address the problem of variability, Storck’s company, 3TIER developed a different approach it felt was more firmly grounded in weather science. The company was among the first to use numerical weather prediction models and historical global weather data, combined with on-site observational data, to try to paint a truer picture of the wind regimes at project sites.

It does not guarantee what will happen in the future, of course, but it does give developers better insight into what they might expect, and what the level of uncertainty – or risk – really is. The technique is designed to prevent unpleasant surprises.

“Several years ago, our work was perceived by many as some sort of black magic,” Storck admits. “But the results speak for themselves, and increasingly the sceptics are some of our best customers. We’ve simply helped them build more successful projects.”

So as you toil over whether or not to invest in some new turbine technology that promises a 0.5% gain in efficiency, remember that getting back to the basics of really understanding your wind resource may pay much bigger dividends, particularly if you’re still basing your business plan on 20 year old methodologies.

The detailed knowledge and understanding of how the weather works more advanced techniques provide are likely to do much more for your business than incremental engineering alone can achieve. And in the long term it’s something that has the potential to be worth a great deal more than the latest mechanical widget could realistically achieve.

Next month:

In part two of this exclusive editorial series, we will assess how financiers and investors can create greater levels of market certainty and investigate what prospective investors can learn from pioneers of the past.

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