Xcel Energy Inc. · NASDAQ:XEL
Xcel Energy — DNV Global Energy Concepts — Technical Presentation (February 2009)
13 slides from Xcel Energy's technical presentation, Feb 10, 2009
Slide 1: Reducing Uncertainty of Wind Power Energy Estimates
Reducing Uncertainty of Wind Power Energy Estimates Presentation for RDF Advisory Board Tony Rogers, Ph.D. DNV Global Energy Concepts Inc. 1809 7th Avenue, Suite 900 Seattle, WA 98101 USA 206-387-4200 Tony.Rogers@dnv.com www.globaenergyconcepts.com 2/10/2009 www.dnv.com
Slide 2: Reducing Uncertainty of Wind Power Energy Estimates
Reducing Uncertainty of Wind Power Energy Estimates • Energy generation affects economics • Reducing uncertainty reduces risks • Used pre- and post-construction data from operating wind farms to identify methods to reduce uncertainty
Slide 3: Participating Projects
Participating Projects S 2 aie RE ee A - 8 e ie & £S eXS The Bahamas Turks any a DNV company
Slide 4: Energy Estimates
Energy Estimates • Energy estimates need: – Wind speeds at each turbine – Average wind speeds over time • Typically wind measured with met towers
Slide 5: Improving Estimates of Wind Speeds at each Turbine- I
Improving Estimates of Wind Speeds at each Turbine- I • How many met towers Tower - 4 per project? Tower - 1 • How estimate wind speeds between Tower - 2 towers? – Use nearby tower data? – Interpolate between Tower - 3 towers?
Slide 6: Improving Estimates of Wind Speeds at each Turbine- II
Improving Estimates of Wind Speeds at each Turbine- II • How estimate wind speeds between towers? – Use tower data and computer models? – Use weather models?
Slide 7: Determining Long-Term Wind Speeds
Determining Long-Term Wind Speeds • Typically, 1-2 years of measured data are compared with nearby long-term data: – Other met towers – Airport data – Weather balloon data – Archived upper-level weather data
Slide 8: Improving Estimates of Average Wind Speeds over Time
Improving Estimates of Average Wind Speeds over Time • Which reference data sets give the best results? • Which methods give the best results?
Slide 9: What We Did
What We Did • Quality controlled and analyzed data from five projects – Data from multiple towers per project – Wind turbine generation data – Reference site data • Tested multiple methods on data from each project – Methods to estimate wind speeds between towers • 234 different cases – Methods to c
Slide 10: Turbine Wind Speed Results
Turbine Wind Speed Results • More met towers better • Flow models and weather models no better than extrapolating between towers Uncertainty of Site-Wide Wind Speed Extrapolation Models One Two Three Four Method Tower Towers Towers Towers Nearest Tower Results 10.2% 8.4% 6.3% 3.2% Distance Weighted
Slide 11: Long-Term Wind Speed Results
Long-Term Wind Speed Results – Reference data sets: Long-Term Extrapolation Uncertainties Met towers 1% • Tower data best ASOS Reanalysis data 2% 11% • Balloon, airport data acceptable Balloon data MOS-corrected NWP 3% 3% – Methods • Two methods with lower uncertainties identified Long-Term Extrapol
Slide 12: Value to Xcel Rate Payers
Value to Xcel Rate Payers • Xcel - #1 wind power provider in US (1/1/2008) • Xcel projects in low complexity terrain similar to three of the sites studied • Research provides information with which to reduce uncertainty of energy estimates • Ultimately reduces project finance risk and costs
Slide 13: GEC a DNV company
GEC a DNV company • Global Energy Concepts (GEC) was acquired by Det Norske Veritas (DNV) effective June 2008. • DNV is a global provider of services for managing risk, helping customers to safely and responsibly improve their business performance. DNV is an independent foundation with presence in m
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