Measure wind speeds for at least a year before turbines are sited

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. 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 sitespecific 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 computergenerated 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.

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. Dr BA Hobbs, Dykeneuk, Peebles Road, Penicuik.