UNCERTAINTY IN WIND RESOURCE ASSESSMENT - Wind Resource Assessment: A Practical Guide to Developing a Wind Project - page 228

4. As discussed in Chapter 12, it is important to adjust the observed data record to
represent the long-term climate conditions, where possible. Explain the impact
of this adjustment from an uncertainty perspective.
5. If there is a trend in the data from a long-term reference station used for MCP,
should its impact on the results be treated as an uncertainty? Why or why
not? Using the Internet or other resources, research and discuss the differences
between uncertainty and bias.
6. Assume your wind monitoring mast records the wind speed at heights less than
your proposed turbine hub height. Referring to the equations in this chapter, what
are some specific measures that can be taken in the design of the monitoring
setup and the analysis of the data to reduce the uncertainty associated with the
extrapolation of the observed values to hub height?
7. What are some ways to design a wind resource assessment campaign that would
minimize the wind flow modeling uncertainty for a proposed project in complex
terrain? Explain why these practices could be effective. What would you have
to do to eliminate this uncertainty altogether?
8. Suppose the wind flow modeling uncertainty for any point within a project area,
based on any single mast, is 8%. Assuming the masts are distributed evenly
throughout the array, what would be the uncertainty in the array-average speed
if there were one, four, and eight masts installed? Take the case of four masts.
Suppose half the turbines were assigned to one mast and the other half were
divided equally among the remaining three. What would be the array-average
uncertainty then?
9. Assume each additional mast in the previous problem costs $25,000 to install and
operate for 1 year. What is the incremental cost per percentage point reduction
in uncertainty gained by going from one mast to four masts and from four to
eight masts? Assume an even distribution of masts within the array.
10. Suppose your wind project has two masts. One mast is associated with the
northern portion of the project area containing 20 turbines; the other is associ-
ated with the southern portion containing 30 turbines. You have estimated the
uncertainty for each of the components and determined whether they are corre-
lated or uncorrelated (see the table below). Using Equations 15.7 and 15.8 and
the method outlined in Table 15-2, estimate the combined uncertainty in the
array-average wind speed.

Source Mast A, % Mast B, % Correlated/Uncorrelated

Measurement 1.5 2.0 Uncorrelated

MCP 3.0 3.0 Correlated

Future resource 2.2 2.2 Correlated

Shear 3.0 2.0 Correlated

Wind flow modeling 4.0 4.0 Uncorrelated