Wind resources at Horns Rev

energy. environment. knowledge. Page 67 of 69
8. Uncertainties
Offshore wind resources can be estimated without using on-site data, but are in that case
subject to considerable uncertainty. Use of on-site data is always preferable, but using
short time series is also a source of uncertainty since wind speeds also vary on a number
of time scales from seconds to decades. Here an attempt has been made to reduce the
uncertainties in the wind resource prediction at the offshore site by using a number of
different methods to establish the relationship between the measured time series
offshore and a reliable long-term time series at Hvide Sande. It is difficult to determine
the relationship between onshore and offshore wind speeds, especially when only short
time series are available.
The Weibull correction method relies on correct fits of the Weibull distribution to the
observed wind speed data in each sector. The MCP method typically predicts lower
wind speeds than the other method: this is most likely due to the problem of correlating
actual wind speed values. As the distance between the measurement and prediction site
increases, the probability of introducing errors into the correlation also increases.
The wave and current data shown in this report are direct plot of the measured data, no
calculations and comparisons have been made, so uncertainties only depends on the
uncertainty from the actual measuring instruments the Waverider and the Workhorse.
Report no.: D-160949
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in energy and environment DK-7000 Fredericia