While met towers are the backbone of the wind industry and serve a range of wind forecasting needs, the value proposition for using met towers alone is rapidly vanishing, according to a research report from Navigant Consulting.
The report, SODAR and LIDAR Remote Sensing Devices, Site Assessment and Permanent Met Towers, and Meteorological Software for Wind Forecasting, indicates that rapid technological advancements have pushed wind assessment equipment far beyond the wind industry's early technologies, such as a conventional 60-meter met tower with a cup anemometer.
Now, remote sensing devices, such as LIDAR and SODAR technology – which measure atmospheric conditions at up to 200 meters high – have narrowed the uncertainty in gathering wind speed and direction at hub height and beyond.
SODAR uses sound detection to measure both horizontal and vertical winds, in many layers, at up to 200 meters above ground, which is much higher than any wind turbine rotor currently available. Similarly, LIDAR uses light detection to assess wind conditions.
Remote sensing devices can help developers launch wind measurements quickly, whereas permitting and/or installing conventional met towers can take weeks or months. Additionally, the devices are portable and can be moved around a potential wind site to help developers understand the wind resource at hub heights, down to a specific turbine location.
A decade ago, the average hub height of a commercial-scale wind turbine was between 65 and 80 meters. Today, a large proportion of turbine deployments in North America and Europe use 100-meter hub heights. A typical 60-meter met tower therefore introduces additional uncertainty at those heights. Most 100-meter towers, however, are not cost-effective for project site assessment; hence, remote sensing devices have entered the market in recent years.
Conventional met towers equipped with anemometers are not going away anytime soon. In fact, met towers are still the most common means of assessing the wind speed and direction at a potential wind farm location.
Just the same, revenue and demand forecasts for met hardware (met towers, SODAR and LIDAR) are expected to exceed $300 million annually by 2020, from $198 million in revenue last year. Unsurprisingly, Navigant notes that annual growth rates are projected to be highest in developing markets, such as Latin America. The research firm notes that top dollar amounts will be highest in Europe, where the most hardware will likely be installed.
According to Navigant, wind currently provides 2.6% of global electricity production and will provide roughly 7.4% a decade from now. For a relatively young technology, this is an impressively high penetration rate – and many regional markets are experiencing much higher percentages.
If good wind resources are coupled with government incentives as a market nudges, the wind industry can continue to grow rapidly. However, Navigant cautions that with growth comes the need to understand and anticipate real-time wind power generation in order to most efficiently integrate this variable resource with the broader electricity grid.
Even minor changes in wind speeds with high wind penetration rates can have large destabilizing effects, according to Navigant.
Denmark's grid operator notes that a 1 meter per second (mps) difference above or below anticipated wind forecasts results in plus or minus 350 MW of generation capacity – equivalent to a large fossil fuel power plant either adding capacity that was not anticipated or slowly dropping off the system.
So critical is precision in forecasting estimates that being off slightly can make or break a project. Moreover, such subtleties can determine whether a wind plant generates profits within expectations or misses generation targets and bleeds a balance sheet into the red.
Generally speaking, a difference of one-tenth of 1 mps in average yearly wind speed can equal $2.50/MWh in a power purchase agreement (PPA) negotiation, according to Navigant. This can make the difference between a wind plant securing a PPA or not. Some PPA deals have been won or lost among competitors over a $0.25 difference in price/MWh.
For more information on Navigant's report, click here.
