Wind Energy Research & Development

Stanford University: The Global Climate and Energy Project (GCEP) R&D Needs Workshop April 26, 2004

Bob Thresher, Director Technology Center Golden, CO Major DOE National Laboratories

h Pacific Northwest µ INEEL Brookhavenh h Argonne Lawrence Berkeley National Renewable X h‹ Energy Laboratory Lawrence Livermore „ NETL

‹ Los Alamos hOak Ridge

‹Sandia

‹ Defense Program n Office of Science „ Energy Efficiency and µ Environmental Management X Fossil Energy Major NREL Program Areas

Supply Side Demand Side Wind Energy Transportation Solar Energy Buildings Technology Biomass/Biofuels Industry Energy Systems Federal Energy Geothermal Management Technology Cross Cutting Hydrogen Research Office of Science Electric Energy Systems and Analytical Studies Storage International Resource Assessment U.S. Energy Consumption by source - 1850-1999

Non-hydro 100 Renewables

s Nuclear 80

Natural 60 Gas Hydro

Quadrillion BTU Quadrillion 40 Crude Oil

20 Wood Coal 0 1850 1870 1890 1910 1930 1950 1970 1990

Source: 1850-1949, Energy Perspectives: A Presentation of Major Energy and Energy-Related Data, U.S. Department of the Interior, 1975; 1950-1996, Annual Energy Review 1996, Table 1.3. Note: Between 1950 and 1990, there was no reporting of non-utility use of renewables. 1997-1999, Annual Energy Review 1999, Table F1b. Affluence Requires Energy – Poverty Breeds Global Insecurity

100 Affluence Japan France United Kingdom 10 South Korea Mexico Poland

El Salvador Russia

1 China

Poverty Bangladesh

GDP Per Capita ($000/person) Burkina Faso 0.1 0.1 1 10 100 1000 Energy Consumption Per Capita ('000 BTU/person) Source: Energy Information Administration, International Energy Annual 2000 Tables E1, B1, B2; Gross Domestic Product per capita is for 2000 in 1995 dollars. Updated May 2002 Changes in Atmospheric Concentration

CO2, CH4, and N20 – A Thousand Year History (ppm) 2 360 (ppb)

1750 4 340 1500 320 1250 300

280 1000

260 750 Atmospheric concentration CO Atmospheric concentration CH

1000 1200 1400 1600 1800 2000 1000 1200 1400 1600 1800 2000

310 O (pbb) 2

290

270

250 Atmospheric concentration N 1000 1200 1400 1600 1800 2000

Source: IPCC Third Assessment Report (2001) National Wind Technology Center

• Sandia National Laboratories • National Renewable Energy Laboratory Growth of Wind Energy Capacity Worldwide

Actual Projected Jan 2003 Cumulative MW = 37,220 Rest of World Rest of World Rest of World = 3,310 60000 North America North America North America = 6,653 Europe Europe Europe = 27,257

d 50000

e l

l 40000

a

t s

n 30000

I

W 20000 M 10000 0 90 91 92 93 94 95 96 97 98 99 '00 '01 '02 '03 '04 '05 '06

Sources: BTM Consult Aps, March 2003 Windpower Monthly, January 2004 *NREL Estimate for 2004

United States Capacity (MW)

Washington Maine Wisconsin Vermont 243.8 0.1 North 53.0 6.0 Montana Minnesota 0.1 Dakota 66.3 562.7 Oregon Michigan New Hampshire 259.4 2.4 South 0.1 Idaho Dakota 0.2 Massachusetts Wyoming 44.3 1.0 284.6 New York Nebraska Iowa 48.5 471.2 14.0 Ohio Utah 3.6 Colorado Illinois Pennsylvania 0.2 50.4 129.0 223.2 Kansas 113.7 West Virginia California 66.0 2,042.6 Oklahoma Tennessee New Mexico 176.3 Arkansas 2.0 206.6 0.1

Texas 1,293.0 Alaska 1.1

Hawaii 6,374 MW as of 12/31/03 8.6 Sizes and Applications

Small (≤10 kW) •Homes (Grid connected) Intermediate •Farms (10-500 kW) • Remote Applications • Village Power (e.g. battery changing, •Hybrid Systems water pumping, telecom sites, • Distributed Power icemaking)

Large (500 kW – 6 MW) • Central Station Wind Farms • Distributed Power • Offshore Wind Generation Stations A Typical Large Turbine has Multiple Subsystems and Controls Stream Tube for Momentum Balance

For Maximum Power: 1 VV= iw3 16⎛⎞ 1 3 PAV= ⎜⎟ρ w 27⎝⎠ 2 The Betz Limit Power coefficient = Performance ofWindTurbines Major Structural Loads Load Sources Electrical Output of a Wind Turbine

Typical Wind Turbine Power Curve Available Mean and Standard Deveation Power (no normalization)

800 Mean Standard Deveation 700

600 Power

500

400 Power Standard Deviation 300 Output Power, kW 200

100

0

-100 0 2 4 6 8 101214161820 Hub Height Wind Speed, m/s Cost of Energy on Land

NSP 107 MW Lake Benton 1979: 40 cents/kWh 4 cents/kWh (unsubsidized)

• Increased Turbine Size • R&D Advances • Manufacturing 2003: 3.5 to 5.5 cents/kWh at Improvements 15 mph sites (30 ft height) DOE Goal for Utility Scale Wind Systems • Develop wind turbines capable of 3 cents/kWh on land and 5 cents offshore in Class 4 (13 mph) wind sites by 2012: • Making more wind sites available close to load centers • Increases the area for wind development by a factor of 20+ • Accelerates meeting the National Energy Trent Mesa, Texas Policy (NEP) for increasing domestic energy sources Technology Improvements Possibilities for Wind Turbines

WindPACT Studies and Analysis www.nrel.gov/wind/windpact/

• Bracketed the Problem • Swept the Possibilities • Identified Opportunities • Now Down Selecting to Most Promising Technology Paths • Least Promising Technical Approaches – High Risk – Low Return – Not Pursued In Current Program Approach Technology Drivers

• Primary Cost Elements – Initial Capital Cost – Balance of Station Cost – Levelized Replacement Cost – Operations and Maintenance – Annual Energy Production

()FCR *(ICC + BOS ) (LRC + O & M ) •COE= + AEP AEP Potential Improvements

• Improvements are Possible in ICC, BOS, LRC and O&M but These Improvements are Limited • Big Gains Will Come From Increases in AEP – Enlarged Rotors – Taller Towers – Taking Advantage of Greater Wind Shear Sites – Improved Component Efficiencies • These Will Demand Control or Reductions in – Loads – Size and Weight of Components – Transportation and Erection Cost Improvements Opportunities

• Technology Improvement Opportunities Have Been Characterized Into the Following – Advanced Enlarged Rotor Designs – Improved Manufacturing – Reduced Energy Losses and Increased Availability – Advanced Tower Concepts – Sites Specific Designs – Increasing Energy & Reducing Losses – New Drive Train Concepts – Advance Power Electronics – Learning Curve Effects • Those in Red Can Logically Be Impacted By Research GE WIND 3.6 MW

GE WIND 1.5 MW Low-Level Jet Turbulence Field Test Wind Program Key Milestone: July 2003 PI: Neil Kelley, NWTC

turbulence

SODAR (acoustic wind profiler)

GE Wind 120 meter meteorological tower south of Lamar, Colorado Technology Challenges: Nocturnal Jet

Source: R. Banta, NOAA

km

km Dynamic Loading Environment

•Wind field = U (y,z,t)

•Steady wind shear superimposed

Rotational sampling effect increases effective wind fluctuations SODAR Measurements Evolution of Low-Level Jet June 17, 2002

Wind Flow Vector wind Wind Speed Contours vector 500 500 (m/s) 450 450

400 400 Mean Wind Speed (m/s) 350 350 8 10 300 300 12 expected turbine upper limit 14 16 250 250 18

200 200 Height above groundlevel (m) 150 150 GE 1.5S 100 100 GE Intense Wind Vertical Shear 50 50 Turbines

01:00:00 02:00:00 03:00:00 04:00:00

(local standard time) Local standard time Initial Conclusions from Lamar Measurements

SODAR Wind Profiles • Low-level jets can 500 Time significantly influence 450 (MST) LWST turbine inflows 400 02:40 02:50 350 03:00 03:10 300 03:20 • Intense vertical shears 03:30 250 03:40 can extend up to at least

Height (m) LWST max height 03:50 200 04:00 200 m 150

100 GE Wind 50 Turbines • Intense shears can 6 8 10 12 14 16 18 20 22 become unstable and 10-minute mean wind speed (m/s) create high levels of organized turbulence Technology Challenges: Unsteady Aerodynamics

NASA Ames 80 ft x 120 ft Test Section The wind tunnel allows the study of aerodynamic stall in a stable flow

Wake flow visualization Wake flow visualization Yaw angle = 0° Yaw angle = 30°

α = 20º ; t = 174 ms α = 25º ; t = 217 ms α = 30º ; t = 261 ms Vortex initiates Vortex grows, moves Vortex sheds International Blind Comparison Benchmarking

4.00 Dynamic Stall Prediction Needs Improvement

Uw = 15 m/s 3.00 Yaw = 60° r/R = 0.47 NREL

n 2.00

C Attached Flow 1.00 Dynamic Dynamic Stall Stall 0.00 0.0 90.0 180.0 270.0 360.0 Blade Azimuth (deg) • Attached flow predictions agree with measured data • Dynamic stall predictions deviate from measured data Technology Challenges: Blade scaling for multi-megawatt designs onshore & offshore

Finite Element 25 Computer Model

Commercial Blade Data 20 Modeling Results

Modeling Results - R 2.9

kg) 15 3 Scaling of Rotors 10

Weight (10 Weight Commercial Blades - R 2.35 5

0 20 30 40 50 60 Rotor Radius (m) Promising LWST Drive Train Concepts

1.5 MW Direct Drive 1.5 MW Baseline

Grid Interface 21 kVrms 3 Transformer

Stator Slip Rings Wound Gearbox Rotor 3 Stage 3 3 Wound-Rotor PE Induction Genrator 1.5MW Multi-Generator Drive Low Wind Speed Turbine Clipper Distributed Drivetrain

Low Speed Shaft View

Generator View showing 8 generators

Patented by Tall Towers

Tall Tower Concepts:

• Novel Steel tubes • Truss towers • Pre-stressed concrete V66 on 117 m tower •Composite • Hybrid towers • Self-erecting/no cranes • On-site manufacturing • Tower load feedback control Offshore Prototype

440 metric tonnes Enercon 4.5MW 112 meter rotor GE Wind Energy 3.6 MW Prototype

•Design concept similar to Boeing 747-200 offshore GE 1.5 / 70.5

•Offshore GE 3.6 MW 104 meter rotor diameter

•Offshore design requirements considered from the outset: –Crane system for all components –Simplified installation –Helicopter platform Offshore Wind Potential for New England

Preliminary Data Offshore Wind Farm Layout : The First Commercial Scale Offshore Wind Farm 2003 • Vestas V 80 – 2MW turbines • 80 Turbines – 160MW off the west coast of Denmark • 14km off the coast in the North Sea • Water Depths ( 5 to 12 meters)

Shallow Water Technology Operations & Maintenance Challenge

• Access To Offshore Turbines Limited by Weather • Access Must be Incorporated Into Designs • Designs Focused on Increased Reliability • Controls and Monitoring Systems From Shore

MIT ADAMS Model

P. Sclavounos, MIT 2003 Offshore R&D Issues Identified by EU Researchers

• Offshore Environment - wind speed/energy potential - turbulence • Wave Loading - Wave spectrum ¾shallow water ¾deep water - Extreme waves - Wind-wave correlation • Turbine Dynamics – Code Enhancement & Validation - Fatigue/linear waves & turbulent wind - Extreme events/non-linear waves • Foundations - Shallow water – monopole, gravity, suction - Deep water anchors • Grid Integration and Transmission to shore • Configurations for Cost Reduction Meteorological • View shed Requirements Tower – 59.74 meters • Environment Studies Utility Grid Interaction Measurements at Lake Benton, Minnesota & Storm Lake, Iowa

100000 Lake Benton and Storm Lake Storm Lake Lake Benton 10-minute Average Power 90000

80000

70000

60000

50000 (kW) 40000

30000

20000

10000

0

Power monitoring is ongoing at: 0:00 6:00 0:00 6:00 0:00 6:00 0:00 6:00 0:00 6:00 0:00 6:00 0:00 6:00 12:00 18:00 12:00 18:00 12:00 18:00 12:00 18:00 12:00 18:00 12:00 18:00 12:00 18:00 1/1/01~1/7/01 • Storm Lake ( 113 MW wind) since January 2001 • Lake Benton II (about 100 MW wind) for two years • Xcel Energy’s Buffalo Ridge substation (about 220 MW wind) since February 2001 Analysis of these data show that: • Wind output fluctuations are 1- 4 % of wind farm rated capacity calculated at one minute intervals over a month Avian Interactions Research

¾ Data suggest the most significant avian wind-turbine interaction problem in the U.S. is in the Altamont WRA. ¾ There is no reason that avian issues should be a concern for future wind farm development; any potential problem should be identified and dealt with before micrositing occurs. ¾ Two guidance documents have been adopted by the NWCC: (1) Permitting of Wind Energy Facilities, and (2) Metrics and Methods for Avian Studies. These two documents serve as guidance for siting and development of new wind farms in the U.S. ¾ Facilities developed following these guidelines have not experienced significant avian impact issues.

NREL Avian Library Available at: www.nrel.gov/wind/avian_lit.html One Interaction Study in Altamont Pass

• Topographical features, turbine location and prey appear to play roles • Not all turbines appear to contribute to fatalities Bat Interactions with Wind Turbines The Problem: • Florida Power & Light’s Backbone Mountain Wind Farm in West Virginia has killed 489 bats since mid summer 2003. • The Backbone Mountain Wind Farm consists of 44 turbines rated at 1.5MW positioned along a prominent Appalachian ridge line. • Bat kills have been recorded at other wind plants in Oregon, Minnesota and Tennessee. • Accurately estimating the number of kills is difficult due to scavenging and poor searcher efficiency. • Knowledge of bat behavior is limited compared to birds.

Photo from BCI A Future Vision for Wind Energy Future Land Based Electricity Path Transmission 2003 Barriers LWST Turbines: Land Based LWST •>3¢/kWh at 13mph Large – Scale • Electricity Market 2 - 5 MW 2012 Bulk Power Generator Cost & Regulatory 3-5¢ at 15mph Offshore Electricity Path Barriers Offshore LWST Turbine: •>5 cents/kWh ƒLand Based Offshore Turbines • Shallow/Deep water 5 MW & Larger •Electricity Market ƒBulk Electricity •Higher wind Sites ƒWind Farms 2012 & Beyond Cost & Infrastructure Advanced Applications Barriers Path Custom Turbines: Potential 20% of Land or Sea Based: •Electricity • Hydrogen •H2 production Electricity Market •Desalinate water • Clean Water •? Cost •Multi-Market 2030 & Beyond