In a concerted effort to improve hub height wind speed and energy predictions, thus reducing financial risk, PPM Energy has conducted sodar campaigns at over 30 diverse locations at eleven project sites. Significantly, the sodar-based findings at some sites have uncovered markedly different above-tower top wind profiles resulting in financially critical conclusions than would not likely have been made, such as optimal hub height selection. At issue is that the wind developer's domain resides within a wind “layer” influenced by a myriad of variables, each complicating the task of defining hub height (≥80 m) and blade sweep (75 to 95 m) wind profiles. Coupled with typical wind monitoring heights of only 50 m to 60 m, the goal of providing accurate wind speed and energy predictions for today's heights has become increasingly challenging. This is bolstered by sodar results which clearly show that wind profiles defined by applying subhub height tower-based wind shear exponents are inappropriate under certain site conditions, resulting in varying degrees of prediction error. Presented case-studies include sites under the influence of thermally driven flow, as well as those located within or in close proximity to complex terrain (flow speed-up) or forest canopies (flow displacement). Identified at the onset, these findings provided the basis for sound project financial assessments and added confidence in PPM Energy's development pipeline. Clearly, to meet industry target penetration goals it is imperative that we foster continued confidence from the financial community by taking every opportunity to improve our wind and energy assessments, such as sodar use demonstrated here.
展开▼
