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Wind Turbines and their Potential for Cost Reductions
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Wind Turbines and their Potential for Cost Reductions

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These slides show how that long-term reductions in the cost of electricity from wind turbines have primarily come more from increasing the scale (rotor diameter and tower height) of wind turbines. See …

These slides show how that long-term reductions in the cost of electricity from wind turbines have primarily come more from increasing the scale (rotor diameter and tower height) of wind turbines. See my other slides for details on concepts, methodology, and other new industries..

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  • 1. Geometric Scaling and Long-Run Reductions in Cost:The case of wind turbines
    SrikanthNarasimalu
    Ph.D. Student
    Jeffrey Funk
    Associate Professor
    Division of Engineering & Technology Management
    National University of Singapore
  • 2. Wind Turbines on Land and at Sea
  • 3. Large Wind Farms in the
    Ocean and on Land
  • 4. Preliminary Observation:Larger Wind Turbines are Being Installed
  • 5. So Conventional Wisdom is Probably Not Very Relevant
    Cost of producing a product drops a certain percentage each time cumulative production doubles in so-called learning or experience curve (Arrow, 1962; Ayres, 1992; Huber, 1991; Argote and Epple, 1990; March, 1991)
    as automated manufacturing equipment is introduced and organized into flow lines (Utterback, 1994)
    Although learning curves do not explicitly exclude activities done outside a factory, the fact that these learning curves link cost reductions with cumulative production
    focuses policy and other analyses on the production of the final product
    imply that learning done outside of a factory is either unimportant or is being driven by the production of the final product
    If major impact of installing more wind turbines was on lowering manufacturing cost, firms would install small wind turbines so there would be high volumes of small blades, towers, etc.
  • 6. Of Course, the Wind Doesn’t Blow Everywhere (and all the Time)
  • 7. Wind Speed Measurements at 8,000 Stations
    Source: http://www.worldchanging.com/archives/002770.html
  • 8.
  • 9. Frequency of Wind Speed in a Ranch in Texas
  • 10. Installed Global Capacity
    of Wind Power (MW)
    2009:
    159 GW
    2010
    194 GW
  • 11. Installed Wind Capacity by Country
  • 12. But Wind Contributes a Small Percentage of
    Overall Electricity Generation (1)
    TWh: Tera Watt Hours
  • 13. Wind Contributes Small Percentage of Electricity Generation (2)
  • 14. How Much Will this Contribution Increase in the Future?
    Blue is actual, red is forecasted
    World Wind Energy Association World Wind Energy Report 2009
  • 15. The Future of Wind Power
    Will wind power continue to diffuse?
    Advantages
    It has lower carbon and other environmental emissions
    Disadvantages
    Wind doesn’t blow all the time (actual output about 1/3 of rated output)
    Wind is often far from large population centers, so transmission costs are high
    Wind turbines are considered ugly by many people
    Wind power is still more expensive than fossil fuels
    But will wind power become cheaper than fossil fuels
    Will countries continue to subsidize wind power or implement a carbon tax?
    Are wind turbines becoming cheaper on an cost per Watt basis?
  • 16. Outline
    Overview of Wind Turbine Costs
    Theoretical Output from Wind Turbines (function of diameter squared, wind speed cubed)
    Empirical Data
    Power output vs. rotor diameter
    Impact of rotor diameter and other factors on rated wind speed
    Cost of wind turbines
    Implications of Analysis
    New materials are needed
    Are new designs needed?
    Where are the entrepreneurial opportunities?
  • 17. Wind Farm Level Costs
    Wind energy: 75% of costs paid upfront
    Conventional power: less capital intensive – uncertain fuel and carbon costs
    Data source: EWEA for a 2MW Turbine.
  • 18. Main Components in Terms of Costs
  • 19. Outline
    Overview of Wind Turbine Costs
    Theoretical Output from Wind Turbines (function of diameter squared, wind speed cubed)
    Empirical Data
    Power output vs. rotor diameter
    Impact of rotor diameter and other factors on rated wind speed
    Cost of wind turbines
    Implications of Analysis
    New materials are needed
    Are new designs Needed?
    Where are the entrepreneurial opportunities?
  • 20. Focus on Horizontal
    Axis Wind Turbine
    Ref: Srikanth in JEC(2009).
  • 21. Three Key Dimensions in Geometric Scaling: 1) rotor diameter;
    2) swept area of blades; and 3) hub or tower height
  • 22. Theoretical Output From Wind Turbine
    (Equation 1)
    P = electric power (energy per second or watts)
    D = rotor diameter (meters)
    V = wind speed (meters/second)
    • Output from rotor depends on square of rotor diameter; thus cost of electricity from wind turbine might fall as diameter increases, as long as cost of wind turbine rises at a rate less than diameter squared
    • 23. Cost of electricity from wind turbine might fall as diameter increases, if larger diameter rotors enable a wind turbine to handle higher wind speeds.
  • Outline
    Overview of Wind Turbine Costs
    Theoretical Output from Wind Turbines (function of diameter squared, wind speed cubed)
    Empirical Data
    Power output vs. rotor diameter
    Impact of rotor diameter and other factors on rated wind speed
    Cost of wind turbines
    Implications of Analysis
    New materials are needed
    Are new designs Needed?
    Where are the entrepreneurial opportunities?
  • 24. Empirical Data Finds Stronger Relationship
    Equation (2)
    Data source from Henderson et al.(2003) & manufacturer catalogue.
  • 25. Reason for Discrepancy
    Above equation does not contain wind velocity:
    which as noted above has large impact on output
    It does not contain wind velocity since the turbines used for the collection of data on power and rotor diameter for Figure 3
    operate under different wind speeds
    these wind conditions depend on the respective region
    The impact of rotor diameter and other factors on wind speed was investigated in four ways
  • 26. First, relationship between diameter and maximum rated wind speed
    Best fit curve:
    Maximum
    rated wind
    speed =
    Data source: Hau (2008).
  • 27. Second, data on efficiency of wind turbines was also collected
    Efficiency is the ratio of annual turbine power output compared to the energy available in the wind
    Less of wind can be harnessed at tips of blades than near center of the rotor
  • 28. Third, Larger Rotor Diameter Better Utilizes Most Common Wind Speeds
    Data source: Vestas website
  • 29. Fourth, Higher Towers, Higher Speeds
    Wind velocity is often lower near ground due to uneven terrain or buildings
    The factor alpha depends on the condition of the terrain and in particular on the impact of the terrain on wind friction and is usually about 0.32
    Combining equations (4) and (1) leads to equation (5). Since the exponent for the ratio of the two heights is 3α, an α of 0.32 would cause a doubling of the tower height to result in a 94% increase in power output.
    Equation (4)
    Equation (5)
  • 30. Comparison of Wind resource at different altitude (Indiana, USA)
    Data source: EWEA
  • 31. Outline
    Overview of Wind Turbine Costs
    Theoretical Output from Wind Turbines (function of diameter squared, wind speed cubed)
    Empirical Data
    Power output vs. rotor diameter
    Impact of rotor diameter and other factors on rated wind speed
    Cost of wind turbines
    Implications of Analysis
    New materials are needed
    Are new designs Needed?
    Where are the entrepreneurial opportunities?
  • 32. Cost of Wind Turbines
    More than 2/3 the cost of electricity from wind turbine farms comes from capital cost of wind turbine and almost half the capital costs are in tower and blades (Krohn et al, 2009)
    Beginning with tower, WindPACT analysis (Malcom and Hansen, 2006) found regression coefficient of 0.999
    c = cost of steel ($/Kg); H = tower height; D = rotor diameter
    Comparing equations (5) and (6), output from turbine increases faster than costs as height is increased.
    For example, if alpha is 0.32 as was shown above and assuming a constant rotor diameter,
    increasing height from 10 meters to 20 meters would cause output to rise by 94% and costs to rise by 9 percent
    Equation (6)
  • 33. Cost of the Rotor:
    Does not increase linearly
    Data source: Hau (2008) and EWEA (2010) .
  • 34. Rotor Cost Per “Swept Area” of Turbine Blades (1)
    Equation (8)
    Equation (9)
    Compare them to Equation (2) in which
    Data source: Hau (2008) and EWEA (2010) .
  • 35. Rotor Cost Per “Swept Area” of Turbine Blades (2)
    Benefits from increasing scale
    diameters < 50 meters; Yes
    diameters > 50 meters; Maybe Not
    “Maybe” because equation (2) does not take into account
    the impact of increased tower height or rotor diameter on maximum rated wind speeds or increased efficiencies.
    Including the increased efficiencies, maximum rated wind speeds, and greater tower heights, which are partly represented by equations (3) and (5)
    would provide a further improvements in our understanding of scaling
    would probably show some benefits to increases in scale
  • 36. Cost of Blades (3)
    The reason for the change in slopes for < and > than 50 meters is that lighter, thus higher cost materials are needed:
    for diameters > 50 meters (carbon fiber-based blades).
    than for diameters < 50 meters (aluminum, glass fiber reinforced composites, and wood/epoxy).
    Early blades can be manufactured with methods borrowed from pleasure boats such as “hand lay up” of fiber-glass reinforced with polyester resin.
    Carbon-based blades require better manufacturing methods such as vacuum bagging process and resin infusion method that have been borrowed from the aerospace industry (Ashwill, 2004)
  • 37. Outline
    Overview of Wind Turbine Costs
    Theoretical Output from Wind Turbines (function of diameter squared, wind speed cubed)
    Empirical Data
    Power output vs. rotor diameter
    Impact of rotor diameter and other factors on rated wind speed
    Cost of wind turbines
    Implications of Analysis
    New materials are needed
    Are new designs needed?
    Where are the entrepreneurial opportunities?
  • 38. Remember the Conventional Wisdom
    Cost of producing a product drops a certain percentage each time cumulative production doubles in so-called learning or experience curve (Arrow, 1962; Ayres, 1992; Huber, 1991; Argote and Epple, 1990; March, 1991)
    as automated manufacturing equipment is introduced and organized into flow lines (Utterback, 1994)
    Although learning curves do not explicitly exclude activities done outside a factory, the fact that these learning curves link cost reductions with cumulative production
    focuses policy and other analyses on the production of the final product
    imply that learning done outside of a factory is either unimportant or is being driven by the production of the final product
    If major impact of installing more wind turbines was on lowering manufacturing cost, firms would install small wind turbines so there would be high volumes of small blades, towers, etc.
  • 39. New Materials are Needed
    Stronger and lighter materials are needed for further increases in scaling
    Lighter materials are needed in order to reduce inertia of large rotors
    Stronger materials are needed to withstand high wind speeds
    Without new materials, there will be few (or no) benefits from further scaling
    Perhaps too large of wind turbines have already been installed
  • 40. Material Technology Choice for Blades
    Note: Squared meters is for swept area of rotor
    Source (Srikanth, 2009)
  • 41. Other Data on Blade Cost Also Reinforces Need for Better Materials
    Ref: Srikanth in JEC(2009).
  • 42. Policy Implications
    Promote adoption of new materials and manufacturing processes for the turbine blades to continue the cost reductions in electricity from wind turbines.
    Support for this R&D (in form of direct funding or R&D tax credits) will probably have a larger impact on reducing costs of electricity from wind turbines than from merely subsidizing their implementation
    Subsidizing their implementation is partly based on notion that costs primarily fall
    as cumulative production rises (Arrow, 1962; Ayres, 1992; Huber, 1991; Argote and Epple, 1990; March, 1991), and
    as automated manufacturing equipment is introduced and organized into flow lines (Utterback, 1994)
  • 43. One Caveat
    Maybe we have reached the limits to scaling
    Maybe it would be better if firms produced large volumes of “optimally” sized wind turbine
  • 44. Outline
    Overview of Wind Turbine Costs
    Theoretical Output from Wind Turbines (function of diameter squared, wind speed cubed)
    Empirical Data
    Power output vs. rotor diameter
    Impact of rotor diameter and other factors on rated wind speed
    Cost of wind turbines
    Implications of Analysis
    New materials are needed
    Are new designs needed?
    Where are the entrepreneurial opportunities?
  • 45.
  • 46.
  • 47. The “Aerogenerator:” Implementation of 275 meter diameter turbine by 2014
  • 48. Tethered Wind Turbine
  • 49. Tethered Wind Turbine
    What about increasing size of fins?
  • 50.
  • 51. Implications for Policy
    Maybe policies should promote the development of these kinds of radical designs
    What are there costs?
    Will they benefit from increases in scale?
    Are new materials needed and what are the impact of these materials on costs of electricity?
    Remember that current policies just encourage the implementation of wind turbines
  • 52. Outline
    Overview of Wind Turbine Costs
    Theoretical Output from Wind Turbines (function of diameter squared, wind speed cubed)
    Empirical Data
    Power output vs. rotor diameter
    Impact of rotor diameter and other factors on rated wind speed
    Cost of wind turbines
    Implications of Analysis
    New materials are needed
    Are new designs needed?
    Where are the entrepreneurial opportunities?