Guys

Attached is an update/reconciliation of the March numbers for Trent and Clear 
Sky.  As you can see the predicted wind energy, based on the actual wind 
speeds for the month, is approximately 20% higher for Trent than it is for 
Clear Sky.  This was a result of the average wind speeds (see monthly 
reports) being 14% higher at Trent: 7.69 m/s vs. 8.8 m/s.  Note that the 
power as wind speeds increase skews the variance in energy higher than the 
variance in wind speeds.

Of particular interest please note that the final curtailment figure has been 
computed and has increased to 11.29 GWh vs. the preliminary numbers of 7.9 
GWh.  

I hope that this helps, please call me with any questions.

JFG
---------------------- Forwarded by Jay Godfrey/EWC/Enron on 04/18/2002 09:24 
PM ---------------------------


Mark Fisher
04/19/2002 09:07 AM
To: Jay Godfrey/EWC/Enron@ENRON, Kurt Anderson/EWC/Enron@ENRON, Bo 
Thisted/EWC/Enron@Enron, Hollis Kimbrough/EWC/Enron@ENRON
cc:  

Subject: CLear Sky/Trent Comparison






Explainations:

Predicted: For each 10 minute interval and each turbine the wind speed was 
converted to a power. The power for each 10 minute interval was then 
averaged, to produce a mean power for the site. This number was then scaled 
by the number of turbines to produce a site wide power value, that value was 
then converted to an energy value.

Curtailment: Curtailment logs were provided by the site giving the turbine 
number and the start and stop time of the curtailment. For each curtailment 
period the wind speed was found. Due to the fact that wind speeds are lower 
on non-producing turbines, the wind speed was scaled up by approximately 5%. 
This wind speed was then converted to power, and then energy. The value of 
the curtailment number is the sum for all curtailments. 

Unavailable: The Curtailment value was removed from the predicted production 
and the result multiplied by the site availability.

Difference: This is a sum total, removing the Curtailment and unavailable 
from the predicted.

Line loss: This is 98% of the Difference to estimate a 2% line loss.

Net: Is the difference of Difference and line loss.

Actual: Is taken directly from the Substation

Variance: Is the difference between the Net and Actual



Curtailed production: Is the amount of  energy not produced due to 
curtailment.
97% Availability: Is 97% of the curtailed production.
2% line loss: Is 98% of the value in 97% availability

Billable Curtailment: Is the value for Curtailment after both availability 
and line loss are taken into account.