American Institute of Aeronautics and Astronautics 1 Uncertainty Analysis in Wind Resource Assessment and Wind Energy Production Estimation Matthew A. Lackner 1 , Anthony L. Rogers 2 , and James.F. Manwell 3 Renewable Energy Research Laboratory, University of Massachusetts, Amherst, MA, 01003 This paper presents a mathematical approach to properly account for uncertainty in wind resource assessment and wind energy production estimation. The evaluation of a wind resource and the subsequent estimation of the annual energy production (AEP) is a highly uncertain process. Uncertainty arises at all points in the process, from measuring the wind speed to the uncertainty in a power curve. A proper assessment of uncertainty is critical for judging the feasibility and risk of a potential wind energy development. Many current methods for assessing uncertainty either oversimplify the process or make faulty assumptions, leading to erroneous estimates of uncertainty. The approach in this paper yields a more accurate and objective accounting of uncertainty, and therefore better decision making when assessing a potential wind energy site. Three major aspects of site assessment uncertainty are presented here. First, a method is presented for combining uncertainty that arises in assessing the wind resource. Second, uncertainty in wind turbine power output and energy production is characterized. Third, a method for estimating the overall AEP uncertainty when using a Weibull distribution is presented. While it is commonly assumed that the uncertainty in the wind resource should be scaled by a factor between two and three to yield the uncertainty in the AEP, this work demonstrates that this assumption is an oversimplification, and also presents a closed form solution for the sensitivity factors of the Weibull parameters. Nomenclature AEP = Annual Energy Production ARRAY = Denotes Array Losses AV = Denotes Availability Losses c = Weibull Scale Factor CF = Capacity Factor ELF = Energy Loss Factor FOUL = Denotes Fouling Losses k = Weibull Shape Factor h = Height HUB = Denotes Hub Height Quantities LT = Denotes Long-Term Quantities or Long-Term Estimation Uncertainty LT_HUB = Denotes Long-Term, Hub Height Quantities M = Denotes Measured Quantities or Measurement Uncertainty N = Number of Measurements P = Power P R = Rated Wind Turbine Power P W (U) = Wind Turbine Power Curve P W ¯ = Average Power Output p(U) = Wind Speed Probability Density Function R = Range of a Rectangular Distribution 1 Ph.D. Candidate 2 Senior Research Fellow 3 Professor Department of Mechanical and Industrial Engineering, 160 Governors Drive, Amherst, MA 01003