Feature

New methods for measuring the wind


Gail Rajgor

Although computer models of wind flow over terrain have improved dramatically in the past few years, there is still no substitute for data recorded at the site.

So you want to build a wind farm. Good for you. With the global drive towards a low carbon economy, it is surely the right way to go for many individuals, companies and, indeed, Governments around the world. As information from the Canadian Wind Energy Association (CanWEA) points out, “from large energy companies to individuals looking to supplement their own energy needs, there's a great future in wind energy.”

But while wind energy can make good economic sense for many, planning and developing a wind farm is, CanWEA adds, “a big ask”.

It's not for the faint-hearted, nor for those in any particular hurry. And in many cases it's not necessarily the right option at all.

In fact, when it comes to developing a wind project from A to Z, there is a minefield of potential obstacles, risks to be factored in, and almost certainly some controversy to be faced (these are explored in greater detail in our article here).

Get it right though and, in the words of the Canadian association, the rewards make it all worthwhile.

Successful wind project development needs proper assessment, the right market conditions in place to make it economically feasible, and a great deal of careful preparation and handling. Wind assessment is arguably one of the first challenges the developer will face.

Trends in wind measurement

The most widely accepted method of measuring the wind at a site has been to use wind sensors mounted on a met mast/tower, recorded by a wind data logger.

For best results, the tower should be at least as tall as the hub of a likely wind turbine, according to wind resource professionals SecondWind: “This can create a challenge as wind turbines can be 80 metres or above at hub height, while the most popular style of meteorological towers used for prospecting – tilt-up temporary masts – are 50 or 60 metres in height.”

The solution in such instances, says SecondWind, is to use remote sensing technologies, such as its Triton Sonic Wind Profiler, which can measure wind at higher heights. More and more companies are now providing these technologies. “In addition to complete wind resource assessment, remote sensing systems can be used for wind prospecting,” the company adds. “The advantage of remote sensing is the substitution of measured wind data for modelled wind data.”

Wind consultants at GL Garrad Hassan agree. “Remote sensing measurement techniques enable measurements to hub height and beyond.” The company says it makes significant use of “value-adding alternative technologies” and this includes resource measurement using sodar and lidar. Its experts, it adds, have been involved in the testing of remote sensors since their market inception and “are therefore well placed to advise on their use as part of a wind monitoring programme”.

In fact, it is fast becoming standard industry practice to use measured data from validated remote sensing technologies in combination with met tower measurements, something viewed as particularly useful when trying to secure financing for wind farms.

In November, for example, developer Continental Wind Partners (CWP) made use of the Triton Sonic Wind Profiler as part of its standard wind resource assessment practice. With a fleet of 8 Tritons, CWP is using the technology to “expedite wind farm development, reduce project uncertainty and streamline project financing” at sites in five Eastern European countries.

In addition to Eastern Europe, CWP is an investment partner in several projects in Australia with Wind Prospect and also plans to use the technology there. “Although met tower data remains a key part, remote sensing is becoming more and more necessary to reduce uncertainty by measuring hub height wind conditions,” says Konrad Gorzkowski, wind & site engineer at CWP.

The company has already accumulated nearly 100,000 hours of Triton data in Central and Eastern Europe. At the earliest phase of the development cycle, Tritons are deployed for wind prospecting – taking an initial measurement of a site's resources to determine whether the site qualifies for a lengthier study with meteorological towers.

On sites with existing met towers, CWP has deployed the system at several locations around the site to better map the available wind resources, an approach known as micro-siting. “Triton always correlates well to the met tower measurements and provides valuable information on each site's profile,” says Maciej Baginski, wind measurement and GIS specialist at PS Wind Management, CWP's Poland-based development group.

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Comments

Anumakonda said

01 May 2011
Excellent article on Wind Measurement. In fact accurate wind measurements at the site are the constraint. Many a time wind data is extrapolated to sites where the wind turbines are to be erected. In the US in California wind farm developers used to monitor(anemometers,Anemographs) in the past at the sites where wind turbines to be erected(Now Wind Masts). This gives more or less reliable wind data and hence the turbine output.Unfortunately in some countries Wind Farm developers can't wait for years to measure the wind data(In some cases to avail the tax benefits quickly) and hence correlate the nearest wind mast data. That is why there will be variation in the output. Moreover terrain also plays an important role in wind energy production.

Dr.A.Jagadeesh Nellore(AP),India
Wind Energy Expert
E-mail: anumakonda.jagadeesh@gmail.com

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