WIND RESOURCE ASSESSMENT FOR THE STATE OF WYOMING Performed by Sriganesh Ananthanarayanan under the guidance of Dr. Jonathan Naughton, Professor, Department of Mechanical Engineering University of Wyoming, Laramie, WY 82071 1 Table of Contents LIST OF FIGURES ............................................................................................................ 2 LIST OF TABLES.............................................................................................................. 2 INTRODUCTION: ............................................................................................................. 3 ANALYSIS......................................................................................................................... 5 RESULTS ........................................................................................................................... 7 Wind resource reports....................................................................................................... 11 CONCLUSION:................................................................................................................ 11 FUTURE WORK:............................................................................................................. 12 REFERENCES ................................................................................................................. 13 APPENDIX 1: WIND ROSE FOR EACH MONTH FOR LARAMIE ........................... 14 APPENDIX 2: WIND RESOURCE ASSESSMENT FOR CHEYENNE....................... 17 APPENDIX 3: WIND RESOURCE ASSESSMENT FOR CASPER ............................. 22 APPENDIX 4: WIND RESOURCE ASSESSMENT FOR ROCK SPRINGS................ 27 APPENDIX 5: WIND RESOURCE ASSESSMENT FOR SHERIDAN ........................ 32 APPENDIX 6: WIND RESOURCE ASSESSMENT FOR GILLETTE.......................... 37 APPENDIX 7: WIND RESOURCE ASSESSMENT FOR RAWLINS .......................... 42 LIST OF FIGURES Figure 1- The state of Wyoming with seven wind sites chosen for South-East Wyoming 4 Figure 2- Probability density function and model distributions for Laramie, WY............. 8 Figure 3- Monthly wind speed profile averaged over six years.......................................... 9 Figure 4 Wind rose graphics for Laramie, WY during summer ....................................... 10 Figure 5-Wind rose graphics for Laramie, WY during winter ......................................... 10 LIST OF TABLES Table 1: Mean wind speed variation with respect to height for Laramie ........................... 8 Table 2: Mean wind speed and Wind power density.......................................................... 8 Table 3: Wind direction during Winter & Summer .......................................................... 10 Table 4: Annual Energy Production Table………………………………………………11 2 INTRODUCTION: Wyoming wind blows strong and persistently thanks to a combination of elevation, topography and weather conditions. High wind speeds throughout the year is very common in Wyoming, especially South-East Wyoming. Towards the central part of Wyoming there is a low spot in the continental divide. This combined with down-flow on the mountains makes for a rich resource of wind. Wind speeds are depicted by classes ranging from one through seven. Class four (> 7.5 m/s) and higher is considered to be highly attractive for power generation using wind energy [1]. Previous research indicates that most of the locations in the south-east part of Wyoming have average wind speeds in excess of those associated with Class 5 [2]. An important term often associated with wind energy production is the capacity factor, which is defined as the ratio of the actual energy produced in a given period, to the hypothetical maximum possible, i.e. running full time at rated power. With a typical capacity factor of 45% [3], Wyoming contains one of the best on-shore wind resource locations in the United States of America. This is very impressive, but does not mean wind plants will be constructed just anywhere in Wyoming. There are plenty of questions to be answered before going further. For instance, are there large fluctuations in the wind speeds annually? What direction does the wind come from? How much power can be generated during a year? To answer these questions, the wind resource at a prospective development location needs to be assessed in detail. A proper wind resource assessment forms a very important phase in the development of utility scale wind farms. In addition, it provides common people with an awareness of the wind resource possessed by Wyoming and the associated economic potential that could be exploited to generate additional revenue for the state. From a strategic standpoint, in addition to the significant coal and gas reserves possessed by Wyoming, energy generated from wind could also significantly diversify the economic portfolio of the state. Wyoming’s phenomenal wind resource has not gone unnoticed. The National Renewable Energy Laboratory and AWS Truepower developed a wind resource map of USA at 80 meters [4], which is the typical height at which utility scale wind turbines’ nacelles are located. The map from the aforementioned study shows the prominence of Wyoming’s wind resource compared to other states. Current wind industry standards show that most of the wind project development is occurring at sites with mean wind speed at hub height greater than 6.5 m/s [5]. All this looks very promising for Wyoming. However there are some important issues we need to address. First and foremost, a readily accessible wind resource report for any chosen location is necessary. A good wind resource report can provide a quick overview of the wind characteristics of the chosen site. In addition, it can point out whether the location needs to be further investigated by installing monitoring stations. The goal of this project was to perform an in-depth analysis of the wind resource for the state of Wyoming. This is done by using the airport wind data recorded for the past few years at chosen locations and using this data to determine the various wind and statistical parameters such as mean wind speed, probability density function, wind power density, and wind rose. As part of this study, all of the above have been incorporated into an 3 easily understood wind resource report that is readily available for the general public. The report also determines estimated annual energy production for a typical utility scale wind turbine. Using this report, the public can develop an understanding of the economic potential of wind energy in Wyoming. Furthermore, the procedure developed as part of this study can be used to conduct a similar assessment at any other location in the world, provided wind data exists for that location. For conducting any analysis associated with wind resource, wind data is required. The more data available, the better the analysis results. The National Climatic Data Center (NCDC), which is the world’s largest archive for climate data [6], keeps a record of wind speeds measured from meteorological towers at a height of 10 meters above the ground, better known as Automated Surface Observing System (ASOS). In total there are 16 ASOS stations around Wyoming. The measurements at the seven chosen sites were representative of the wind resource needed for commercial wind development, with special emphasis on South-East Wyoming. The wind data from January 1, 2006 to July 7, 2012 for the following sites were analyzed as part of this study: Laramie (KLAR), Cheyenne (KCYS), Casper (KCPR), Rock Springs (KRKS), Gillette (KGCC), Sheridan (KSHR), and Rawlins (KRWL). These locations are depicted in Figure 1 below. Figure 1- The state of Wyoming with seven wind sites chosen for South-East Wyoming wind resource assessment ASOS records the wind speed, direction, temperature, and pressure. For this study, wind speed and direction were the two parameters considered. The raw data was reviewed for errors, and the corrupted data was eliminated. The biggest advantage of collecting large volumes of data is that it provides a good basis for characterizing the wind resource at any given location. For each of these sites, the probability density function (pdf) was developed. After calculating the necessary parameters, the mean wind speed was determined from the pdf. wind power density, average wind speed profile, wind rose, and potential annual energy 4 production for a utility scale wind turbine was determined. This procedure has been automated using a MATLAB routine that can handle wind data of any location in the world. ANALYSIS PROBABILITY DENSITY FUNCTION A probability density function is a function associated with wind data that shows the relative frequency with which a particular wind speed occurs or intuitively it is related to the percentage of time that wind blowing at a particular location achieves a certain speed. Hourly wind data implies discrete wind data. The bin spacing is determined by the MATLAB routine according to the data collected. Each set of wind data has its own bin spacing. The number of bins are then used to develop a histogram which provides us with a good distribution of the data. Finally, the histogram is normalized using the empirical formula below, to obtain the probability density function for the location. pdf (u) = histogram(u)/(n*delta_u); where delta_u= bin spacing ; n = total number of bins; The mean wind speed for each location is obtained from the probability density function using the equation. u ( pdf (u) *u * delta