The Impact of Technology on Wind Farm Development
Over the past 10 to 15 years, enhancements in technology and computing power have truly revolutionized the wind development business. From prospecting the best sites to constructing wind farms, from mapping cadastral data to estimating the wind resource at specific proposed turbine locations, technology has improved our ability to efficiently select, develop, and ultimately construct utility-scale wind farms.
Site Prospecting for Wind Farms
Ten to 15 years ago, wind development was a very different industry than it is today. Few people, if any, had access to Geographic Information Systems (GIS) software tools and databases. Investigating optimal sites to develop a wind farm usually meant traveling with a meteorologist by car throughout rural parts of the country to find the windiest area, then searching for nearby transmission lines. Researchers would use hard copy topographic maps from the United States Geological Society (USGS) as a reference to seek the highest, most exposed terrain.
Today, site prospecting is conducted in a very different manner. Advanced atmospheric computer models and robust computing power have allowed atmospheric scientists to derive high resolution (e.g. 200 meter) wind resource maps that cover the globe. Scientists are able to derive long-term wind speeds at various heights above ground surface by initializing these models with observed atmospheric data. Government entities such as the National Renewable Energy Laboratory (NREL) have made many these maps available to the public. And companies such as AWS Truepower and 3Tier sell other wind resource maps in GIS formats.
GIS platforms allow developers to overlay additional layers of information on top of wind maps, such as transmission lines and substations, protected areas, elevation, and even airport, radar and power price data, to ultimately select the optimal sites for a wind farm. By using complex queries, the developer can specify certain criteria such as “the wind resource needs to be at least XX strong, and the proposed site has to be within XX miles of a transmission line.” The GIS software program will return all of the sites that fulfill these criteria within the domain in an automated manner. All of this can be done from an office without ever having to set foot outside.
Mid-Stage Development of Wind Farms
Years ago, once developers selected the general area to build a wind farm, they would typically go directly to the county hall to obtain landowner information (cadastral data). In a strategic effort to secure land, the developer would slowly begin to contact landowners in the vicinity of the proposed wind farm and lease the land for future development. In many states, such as those in the Great Lakes, this meant gathering data on hundreds of landowners with paper maps and spreadsheets.
Today, many counties throughout the U.S. have created GIS cadastral maps that can be accessed via Web sites or downloaded in a GIS format. By loading this information into a GIS system, the developer can overlay landowner information on top of all the other layers mentioned above to determine which landowners should be contacted. The developer can extract all of the descriptive details along with landowner contact information by simply highlighting the desired parcels with a cursor. What used to take days can now be accomplished in a matter of hours.
Wind Resource Assessment
In order to have a “bankable” wind project, it is necessary to collect at least one year of onsite data with a meteorological (MET) tower to validate estimates of the onsite wind resource. Years ago, MET towers were 40 to 50 meters in height, as actual turbine hub heights were only 50 or 60 meters in height.
The data loggers collecting the wind data at the MET tower could only store a few weeks’ worth of data before system memory filled. When these few weeks had elapsed, someone would have to physically go to the MET tower, download the data, and then erase the databanks so new information could be collected. This situation would often lead to weeks of missed data due to lack of memory restoration or unnoticed instrument malfunctions.
Today, with advancements in material science and computers, MET towers have increased in height (typically 60 to 80 meters) and turbine hub-heights now typically span between 80 and 100 meters. These taller turbines can take advantage of the more robust winds at greater heights. Data logger cards can now store several years of wind data, and new ipacks allow this data to be transmitted via email directly to the developer on a daily basis. Such technology now permits scientists to review the data in “real time” to maximize overall data recovery rates and quality.
One of the challenges in wind resource assessment has been extrapolating the wind data collected at the MET tower locations out to the proposed turbine locations. For example, if a MET tower is positioned on a hill, and one of the proposed turbines is in a valley, the wind resource will differ at these two locations. In the past 5-10 years, computing technology has improved dramatically, which has allowed for more complex computational fluid dynamic (CFD) models to be developed and run on the average home computer. These CFD models can be used to estimate the wind resource throughout the entirety of a site with complex terrain.
Technology has impacted all stages and aspects of the wind development business. When it comes to developing a wind farm, success matters to the developer, the investors, the landowners and the community. Now, with smart tools that can reveal so many answers from the outset of the development process, a substantial amount of up-front time, cost and risk is removed, which makes success much more likely.
By Jason Lowenstein, OwnEnergy
July 19, 2011