How to measure up to expectations  The more accurate the wind
measurements on a proposed site, the more likely the wind farm
is to deliver on its expected energy yield. Here David Milborrow
explains how developers tackle this potentially lengthy process
and the many variables involved.  Anemometors are sited at
regular intervals Anemometors are sited at regular intervals The
ability of a wind farm to deliver the forecast energy yield is
critical to its economic viability. Unlike a conventional
thermal power station, the yield is dependent as much on the
wind speed, which varies from year to year, as on the rated
output.  It is likely to take several months, preferably a year,
until this potential can be established with some accuracy.
Once it is determined, however, estimation of the energy yield
of the wind farm is a reasonably straightforward process that
takes into account the characteristics of the chosen wind
turbines, the wake losses, electrical losses on the site and the
expected availability of the t