Wednesday, 25 January 2012: 10:30 AM
State of the Art Improvements in Atmospheric Boundary-Layer Science Needed to Support Wind Energy
Room 345 (New Orleans Convention Center )
“When someone flips a switch, the lights must come on,” is the often stated “Priority Number One” for electricity dispatchers, illustrating how the energy industry has limited tolerance for uncertainty. Meteorology, on the other hand, is a field where uncertainty is not only tolerated, but even expected. This represents a significant disconnect for wind energy (WE), and other renewable sources such as solar, since the large uncertainties in the information on which major decisions must be based can often be risking $10s to $100s million or more. Decisions involve activities that span the WE development process from hardware design to siting to operations, including forecasting. WE is especially vulnerable to shortcomings in atmospheric information because 1) it requires a level of precision much higher than previous meteorological applications, and 2) information is required in a layer aloft, not at the surface where the preponderance of measurements are taken. The lack of high-quality measurement data in and above the turbine rotor layer means that processes affecting the winds there are not well characterized or understood, and the fidelity of NWP in those layers is also not well known, although available evidence indicates errors and uncertainties too large for WE needs. The need for improved measurements has been documented but the quality (precision, resolution, frequency) of measurement required to meet the needs of WE has received less attention. Recent focus has been directed at the importance of matching measurement-system capabilities with the phenomena to be measured. A problem currently facing WE is that the characteristics and properties of those phenomena as well as factors controlling the wind speed and its variability in the rotor layer are largely unknown, because of the lack of measured datasets in and above this layer. In other words in many cases, we don't even know what the dominant flow phenomena are up there. Thus, the critical first step to improving atmospheric science support for WE is to obtain measurements using appropriate instrumentation to identify and begin to characterize meteorological processes in the rotor layer, to answer the question, what is it that we need to understand and model better? At a minimum, high-quality measurements are essential through the 50-150-m layer above ground, but measurements of a deeper layer are also very important to provide meteorological context and insight into the processes driving the flows. An instrument capable of sufficiently high spatial and temporal resolution, and sufficiently high precision, to address WE issues is a scanning, pulsed Doppler lidar developed and operated by NOAA/ESRL. This instrument has provided detailed wind data in and above the rotor layer, where most needed, in several field programs. In this presentation we review results of analyses from these datasets to illustrate the challenges facing meteorology in supporting WE, and to propose steps needed to advance the state of the art to levels required by WE. These steps include evaluation of instrumentation capabilities to see which have the ability to address WE needs, design and implementation of all-weather multi-instrument profiling test sites, design and deployment of multi-scale sampling array layouts to address the breadth of WE requirements, and assessment and improvement of numerical modeling capabilities.