AE/ME Wind Engineering Module 1.2

1. AE/ME Wind EngineeringModule 1.2 Lakshmi Sankar lsankar@ae.gatech.edu

2. OVERVIEW • In the previous module 1.1, you leaned about the course objectives, topics to be covered, and the deliverables (assignments) • In this module, we will first review the history of the wind turbines • We will also learn some basic terminology associated with wind turbines • We will also discuss what factors go into choosing sites where you may build/deploy your own wind turbines or farms. • We will conduct this discussion through case studies.

3. History of Wind Turbineshttp://www1.eere.energy.gov/windandhydro/wind_history.html • Technology is old, in some respects! • Wind was used to propel sail boats as early as 5000 BC in Egypt. • Chinese used wind energy to pump water by as early as 200 BC • Persians used wind energy about the same time to grid grain • By the 11th century, people in the middle east were using wind mills for food production • Traders and crusaders carried the ideas to Europe.

4. History of Wind Turbines (Continued..) • Dutch were looking for ways of draining lakes and marshes. • Wind turbines became very popular. • The technology spread to US when settler brought these ideas to America. • Industrialization (use of coal to generate steam) brought a decline in the use of wind energy. • Steam engines replaced wind mills for pumping water and producing electricity. • Rural electrification began in the 1930s. • Wind turbines had to make their case economically! • Their popularity rose and fell with the availability and cost of alternative forms of energy production. • Oil crisis in the 1970s and energy crisis during the past decade has brought wind energy’s potential as a clean, renewable, sustainable, energy source,

5. Wind Power's Beginnings (1000 B.C. - 1300 A.D.) • Persians used the drag of the blades (i.e. aerodynamic force along the direction of the wind) to generate rotation of the blades. • Struts connected the sails to central shaft. • Grinding stone was attached to the central shaft. • Only one half of the turbine was useful at any instance in time.

6. Early Designshttp://www.telosnet.com/wind/early.html

7. Lift vs Drag • The aerodynamic force along the direction of the wind is called drag • Early wind turbines used drag to generate the torque. • The aerodynamic force normal to the wind direction is called lift. • For a properly designed blade (or airfoil) lfit to drag ratio may be 100 to 1! • Dutch began using lift force rather than drag to turn the rotor. • Over the past 500 years, the design has evolved through analysis and experimentation.

8. Use of Drag to Produce Torque Pelton Wheel uses this concept Drag Force Wind

9. L D Lsinf Dcosf Wr f Vwind - Vinduced Use of Lift forces for Torque Production Propulsive force = Lsinf - Dcosf

10. Wind Turbine History in the US • During the 19th century wind mills were used to pump water. • Rotor diameter reached 20 meters. • Water was used to operate steam engines, • Eray designs used wood as the material and had a paddle like shapes. • Drag force was used. • Later designs used steal blades which could be shaped to produce lift forces. • The blades spun fast, requiring gears to reduce the angular velocity. • Mechanisms were developed for folding blades in case of high winds. • In 1888, electricity was produced using the wind turbine shown on the lower right by Charles F. Brush. • By 1910s, coal and oil fired steam plants became popular, and the use of wind turbines became less common.

11. Installed Wind Power Generation (in MW)http://www.windenergyinstitute.com/installed.html

12. Basic Terminology • Vertical Axis (or Darrieus) Wind Turbines vs. Horizontal Axis Wind Turbines • We will study HAWTs in this course.

13. Terminology (Continued)http://www.energybible.com/wind_energy/glossary.html • Availability Factor • The percentage of time that a wind turbine is able to operate and is not out commission due to maintenance or repairs. • Capacity Factor • A measure of the productivity of a wind turbine, calculated by the amount of power that a wind turbine produces over a set period of time, divided by the amount of power that would have been produced if the turbine had been running at full capacity during that same time interval.

14. Terminology (Continued) • Rotor • Comprises the spinning parts of a wind turbine, including the turbine blades and the hub. • Hub • The central part of the wind turbine, which supports the turbine blades on the outside and connects to the low-speed rotor shaft inside the nacelle. • Root Cutout • The percentage of the rotor blade radius that is cut out in the middle of the rotor disk to make room for the hub and the arms that attach the blades to the shaft. • Nacelle • The structure at the top of the wind turbine tower just behind (or in some cases, in front of) the wind turbine blades that houses the key components of the wind turbine, including the rotor shaft, gearbox, and generator.

15. Parts of a Wind Turbine • Turbine controller is connected to the rotor. • Converter controller, connected to converters and main circuit breaker, is needed to control the output voltage and power

16. Wind Power Classificationhttp://www.awea.org/faq/basicwr.html

18. The following slides are from a Presentation in 2002 byAmerican Wind Energy Association

19. Wind Power is Ready Clean Energy Technology for Our Economy and Environment American Wind Energy Association, 2002 Image courtesy of NEG Micon

20. Wind Power Market Overview

21. Ancient Resource Meets 21st Century Technology

22. Wind Turbines:Power for a House or City

23. Ready to Become a Significant Power Source Wind could generate 6% of nation’s electricity by 2020. Wind currently produces less than 1% of the nation’s power. Source: Energy Information Agency

24. Wind is Growing Worldwide 1. Germany: 8754 MW 2. U.S.: 4260 MW 3. Spain: 3195 MW 4. Denmark: 2492 MW 5. India: 1507 MW Source: AWEA’s Global Market Report

25. Wind Taking Off in the U.S. • U.S. installed nearly 1,700 MW in 2001 • Wind power capacity grew by 66% • Over 4,265 MW now installed • Expecting over 2,500 of new capacity in 2002-2003 combined Source: AWEA’s U.S. Projects Database

26. United States Wind Power Capacity (MW) New Hampshire 0.1 Maine 0.1 Washington 180.2 Vermont 6.0 Wisconsin 53.0 Montana 0.1 North Dakota 1.3 Minnesota 322.7 Oregon 156.9 Michigan 2.4 South Dakota 2.9 Massachusetts 1.0 Wyoming 140.6 New York 48.2 Iowa 324.3 Nebraska 3.5 Utah 0.2 Pennsylvania 34.5 Colorado 61.2 Kansas 113.7 California 1,715.9 Tennessee 2.0 New Mexico 1.3 Source: AWEA’s U.S. Projects Database Texas 1,095.5 Alaska 0.9 4,270 MW as of 07/31/02 Hawaii 1.6

27. Washington 180 Wisconsin 30 New York 30 Minnesota 218 Oregon 132 Main Areas of Growth in 2001 Iowa 82 Pennsylvania 24 Kansas 112 1,697 MW added in 2001 Texas 915 Source: AWEA’s U.S. Projects Database

28. U.S. Wind Power Capacity Growth *Source: AWEA’s U.S. Projects Database

29. Wind Power Economics

30. Cost Nosedive Driving Wind’s Success 38 cents/kWh 2.5-3.5 cents/kWh Levelized cost at excellent wind sites in nominal dollars, not including tax credit

31. Wind Power Cost of Energy Components Cost (¢/kWh) = (Capital Recovery Cost + O&M) / kWh/year • Capital Recovery = Debt and Equity Cost • O&M Cost = Turbine design, operating environment • kWh/year = Wind Resource

32. Revenue Streams Commodity Power Sale: $30-$45/MWh Production Tax Credit: $18/MWh “Green Credit”: New Market, Values Vary Debt/equity ratios close to 50%/50% Increased debt/equity ratios can significantly increase return Capital Costs

33. Long-Term Debt • Better loan terms with longer-term power purchase agreement (PPA) • Loan terms up to 22 years, determined largely by PPA

34. Return requirements vary with risk Perceived risk of wind projects may be larger than real risk Returns evaluated after tax credit Wind energy projects can expect return in low teens (10% to 15%) Equity Considerations

35. Turbine Technology Constantly Improving • Larger turbines • Specialized blade design • Power electronics • Computer modeling produces more efficient design • Manufacturing improvements

36. How big is a 2.0 MW wind turbine? This picture shows a Vestas V-80 2.0-MW wind turbine superimposed on a Boeing 747 JUMBO JET

37. Construction Cost Elements

38. 100 80 60 % Available 40 20 0 Year 1981 '83 '85 '90 '98 Technology Improvements Leads to Better Reliability • Drastic improvements since mid-80’s • Manufacturers report availability data of over 95%

39. Improved Capacity Factor • Capacity Factors Above 35% at Good Wind Sites • Performance Improvements due to: • Better siting • Larger turbines/energy capture • Technology Advances • Higher reliability • Examples: Project Performance (Year 2000) • Big Spring, Texas • 37% CF in first 9 months • Springview, Nebraska • 36% CF in first 9 months

40. Bottom Line20 Years of Wind Technology Development Economy of scale reduces price per kw of capacity Technology improvements yield more energy bang for the buck Combined, they dramatically reduce turbine price per unit of energy produced

41. Benefits of Wind Power

42. Advantages of Wind Power • Environmental • Resource Diversity & Conservation • Cost Stability • Economic Development

43. Benefits of Wind PowerEnvironmental • No air pollution • No greenhouse gasses • Does not pollute water with mercury • No water needed for operations

44. Electricity Production is Primary Source of Industrial Air Pollution Source: Northwest Foundation, 12/97

45. Benefits of Wind PowerEconomic Development • Expanding Wind Power development brings jobs to rural communities • Increased tax revenue • Purchase of goods & services

46. Benefits of Wind PowerEconomic Development Case Study: Lake Benton, MN $2,000 per 750-kW turbine in revenue to farmers Up to 150 construction, 28 ongoing O&M jobs Added $700,000 to local tax base

47. Domestic energy source Inexhaustible supply Small, dispersed design reduces supply risk Benefits of Wind PowerFuel Diversity

48. Flat-rate pricing can offer hedge against fuel price volatility risk Electricity is inflation-proof Benefits of Wind PowerCost Stability

49. Wind Project Siting

50. Siting a Wind Farm • Winds • Minimum class 4 desired for utility-scale wind farm (>7 m/s at hub height) • Transmission • Distance, voltage excess capacity • Permit approval • Land-use compatibility • Public acceptance • Visual, noise, and bird impacts are biggest concern • Land area • Economies of scale in construction • Number of landowners