Wind speeds must be measured for at least a year before turbines are sited – Herald (letters)

WIGTOWN conservationists berate the renewable energy firm Ecotricity for
its “disrespectful” application to erect a wind farm before the result of
their appeal to erect a meteorological mast is decided (Wind farm plan is
‘disrespectful'”, The Herald, February 23).

Ecotricity’s response is to say that erecting such a mast (to measure wind
speed) is not a planning requirement. The question should be asked “why not?”

Developers regularly claim, as Ecotricity do in this case, that their
development will help cut Scotland’s carbon emission and generate
electricity for (in this case) 50,000 homes. The adverse effects of
industrialisation via windfarms is well documented and planning regulations
dictate that development should only be allowed if benefits outweigh
adverse effects. Without site-specific wind speed measurements those
benefits cannot be calculated.

Long-term wind speed measurements determine the amount of electricity
likely to be generated and hence the number of homes that could be powered.
The measurements also enable some rudimentary calculations to be made of
possible carbon emissions savings.

Ecotricity says it already has extensive site specific wind data from
existing wind databases. If so, then why the need for a mast? Presumably it
is referring to the Numerical Objective Analysis of Boundary Layer (Noabl)
data base from which site-specific data can be extracted. However this
database, quoted generally in most wind farm applications, is based on no
measurements at all. It is simply a database formed from computer-generated
models in a bare earth scenario. Noabl is no longer supported and
inadequacies were revealed following a failed wind farm application at
Auchencorth Moss, Scotland. The database gave a figure of 7.4 m/s for the
yearly wind speed average at a height of 45m. It transpired that on-site
measurements taken over four4 years (during the application process) gave
an actual average of 5.17 m/s at 45m. Since the amount of electricity
generated depends on the cube of the wind speed, the generated electricity
would have been only one-third that predicted in the application. Similarly
there would have been much smaller savings in emissions.

Thus to assess benefits of a wind generation project, it is vital to
measure wind speeds on site over at least a one-year period and this should
indeed be a planning requirement to be completed before application is made.

Dr BA Hobbs,
Dykeneuk,
Peebles Road,
Penicuik.