3TIER is a renewable energy consulting firm focused on wind and solar resource assessment. They provide pre-construction services like spatial mapping of wind resources, climate variability analysis, and comprehensive net energy reports. Their assessments use numerical weather prediction models with high resolution terrain data to generate synthetic wind data time series. They incorporate on-site observational data using model output statistics to remove bias from the synthetic data. Their most complete assessment is a project-wide net energy analysis using a 40+ year time series simulation that accounts for wakes, losses, and uncertainty.

1. How to reduce risk
Presented by:
Matthew Hendrickson, Sr. Director Of Assessment

2. 3TIER is Focused on Understanding the Fuel
» Founded in 1999
» Headquarters in Seattle, WA
» Offices in Panama, India, and
Australia
» Focused on renewable energy
information services
 39,000 MW wind energy
forecasting
 7,400 MW hydropower
forecasting
 Extensive international
wind & solar resource
assessment

3. Pre-construction services
I. Spatial mapping
II. Climate variability analysis
III. Comprehensive net report
A. Spatial
B. Climate
C. Wake
D. Other losses
E. Uncertainty

4. What is Numerical Weather Prediction?
INPUTS WRF ANALYSIS OUTPUTS
Global
Weather
Archive
1960-present
Understanding of
wind characteristics
High
Resolution Long-term variability
Terrain, Soil, assessments
and Vegetation
Data (up to 50 years)
Spatial wind maps
OPTIONAL:
Onsite
Observations

5. The Value of Higher Resolution Wind Mapping
5km resolution 1.5km resolution 500m resolution
8.0
Look at the two locations marked on each map…
Sweetwater Nearby Mountain
At 5km resolution = ~7.1m/s ~7.5m/s
At 1.5km resolution = ~6.9m/s ~7.7m/s
7.0
At 500m resolution = ~6.8m/s ~8.0m/s
6.0

6. The Value of High Resolution Wind Mapping
5km resolution 1.5km resolution 500m resolution
8.0
. . . and understand the
spatial variability of the wind
7.0 90m resolution resource, better than with
simple statistical
~9.0 m/s at mountain extrapolations and/or
6.0 interpolations of on-site
observations

7. Avoid Wind Holes!

8. Options for Understanding Long-term Variability

9. Using Nearby 3rd Party Station Data
Measure-Correlate-Predict
(MCP)

10. Traditional MCP
Measure-Correlate-Predict
Reference ✪
Site
ws=m*wsr+b
Uses a statistical relationship
between on-site obs data and a
longer ‘reference’ site to
understand the variability of the
wind resource and determine a
long-term adjustment

11. Traditional MCP
Measure-Correlate-Predict
» Reference site needs to be a consistent, long-term time
series located within a similar flow regime as the project site
» For robust results, MCP requires high correlation between
reference site and on-site, project data
» What to do if suitable long-term reference data are not
available?

12. Using Synthetic Reference Data
Numerical Weather Prediction Models

13. Synthetic Reference Data – Using NWP Models
» Unlike MCP analysis, Numerical Weather Prediction (NWP)
models do not require off-site reference data.
» Over 50 years of historic wind resource data at hourly
resolution can be generated utilizing NWP models
» Synthetic reference data are provided at the project-site

14. Numerical Weather Prediction Framework
Input Output
Global Weather Understanding
Archive of Wind
1948-present Characteristics
Numerical
Weather
High Resolution Long-Term
Prediction Model
Terrain, Soil, and Variability
Vegetation Data (NWP) Assessments
On-Site Spatial
Observations Wind Maps

15. NWP Output – Annual-mean Variability
NWP wind speed Observed wind speed
Long-term mean Operational wind speed

16. NWP Output – Monthly-mean Variability
Capacity Factor
Based on single year of observations, compared to 40 year analysis

17. Validation of 3TIER NWP Time Series
Comparison Against Reanalysis

18. Skill of Reanalysis Data
287 QC’d Tall Towers
Average R=0.53
Median R=0.55
STD R=0.19

19. Skill of 3TIER Data
287 QC’d Tall Towers
Average R=0.70
Median R=0.71
STD R=0.08

20. Skill of 3TIER Data - Independent Validation
Wind energy index comaprison Wind energy index comaprison
200 200
y = 0,9692x + 2,6531
180 180 R² = 0,8772
160 160
y = 0,5507x + 44,931
R² = 0,6706
140 140
120 120
3Tier 20m
NCAR
100 100
80 80
60 60
40 40
20 20
0 0
0 20 40 60 80 100 120 140 160 180 200 0 20 40 60 80 100 120 140 160 180 200
ElZayt NW 24,5m ElZayt NW 24,5m
"Our preliminary findings show that 3TIER wind data can
significantly reduce long-term correction error compared to
using NCAR/NCEP data, which is often the only option due to a
lack of reliable long-term ground measurements.
Per Nielsen - EMD Manager

21. Incorporating On-site Observational Data
with
Numerical Weather Prediction Models
Model Output Statistics
(MOS)

22. Incorporating Observational Data
At any particular location the best way to
determine the wind resource is through direct
measurement.
3TIER incorporates observational data into
wind assessments whenever suitable on-site
data are available for
• Validation
• Statistical correction

23. Incorporating Observational Data - MOS
• MOS (Model Output Statistics) is a statistical technique to
remove bias & adjust the variance of NWP model data to
better match the on-site observed data
• NWP models simulate the full structure and time evolution of
the atmosphere. MOS relates the observed wind speed to
the leading NWP predictors to improve the quality of the
long-term estimate of the wind resource.
• The output of the MOS algorithm is a multi-linear equation
that is applied to all times of the analysis on an hourly basis
(windspeed_97m * 1.25) + (windspeed_200m * 0.51) + (u_200m * 0.07) +
(temperature_0m * -0.06) + 18.93

24. MOS-Corrected Output – Monthly-mean Variability

25. Validation of MOS-Corrected Time Series
Influence of observational record length

26. Skill at Monthly-mean Timescale
Raw Model Data MOS-Corrected Model Data
Analysis performed with Horizon Wind Energy utilizing 299 tall towers
MOS-corrected standard deviation of error for an individual month = 7.8%

27. Skill at Annual-mean Timescale
Raw Model Data MOS-Corrected Model Data
Analysis performed with Horizon Wind Energy utilizing 299 tall towers
MOS-corrected standard deviation of error for an individual year = 3.4%

28. MOS skill utilizing short observational records
A single month of observational data helps to remove bias
MOS-corrected errors decrease throughout first year of observed record

29. MOS skill utilizing short observational records
MOS-corrected errors decrease throughout first year of observed record

30. Comparing Skill of
3TIER MOS & MCP
Results based on 23 met
towers each with 5 years
of obs data
Obs data and MCP
analysis provided by
Horizon Wind Energy
3TIER MOS
MCP

31. Wake Modeling
• 3TIER’s super computing
capabilities allow unique
ability to model wakes in
time series across all
climatic conditions.
• Classical engineering
solutions require climatic
conditions to be condensed
into distributions, disguising
important features like
performance in atmospheric
stable conditions

32. Other losses
» Turbulence
» Shear
» Inflow angle
» Electrical system
» Availability
» Turbine performance
» Environmental
» Blade degradation
» Icing
» Wind sector management
» High speed start/stop hysteresis

33. Comprehensive Assessment
• 3TIER’s most complete solution, provides finance quality
energy assessment
• Project-wide, net energy assessment based on the last 40+
years of MOS-corrected NWP model data
• Adds a site-visit, quality control of obs data, full uncertainty
analysis, and gross-to-net analysis to a FullView Project
Resource Assessment
• Uses 3TIER’s proprietary time-varying wake modeling
analysis to understand diurnal and seasonal variability of
wakes, wind speed deficits, and turbulence intensity

34. Comprehensive Assessment
Full, time series simulation at every turbine across historic record

35. Comprehensive Assessment
Multi-staged observation QC process

36. Comprehensive Assessment

37. Comprehensive Assessment
Comprehensive uncertainty analysis highlights risk associated
with measurements, shear, spatial modeling, temporal
modeling, generation, wake modeling, etc…

38. Other Services
• Power Performance Testing – per IEC 61400-
12-1 standards
• Operational reforecast services – reassess the
long term production of a plant after operational
data is available
• Operational forensic services – root cause
analysis to “deep dive” into SCADA data and
attempt to explain variations on production
against expectations.
• Etc… 3TIER’s Advanced Applications group
positioned to tackle any challenges in need of
scientific solution.