ÊParts of the blade broke off on Thursday morning and only a fraction of it remains attached to the tower. The remaining 19 turbines had shutdown by the time the accident was discovered but these were restarted on Sunday after checks were carried out. There was no one on site or near the area at the time.
ÊNews of the incident has led campaigners opposed to further wind farm development in the Lammermuir Hills to question the safety of wind technology.
ÊKate Knight, chairman of the Lammermuir Protection Group, said: "You can only imagine the horrific consequences if someone were in the vicinity at the time. Rights of way including historical routes such as the Herring Road and Southern Upland Way run through or near wind power sites both planned and operational Ñ sites including Crystal Rig, Black Hill and Fallago Ridge. These are clearly not safe places to go if broken turbine parts can be flung for hundreds of metres. Large tracts of the Lammermuirs could become no-go areas."
ÊCrystal Rig began operating last summer and is currently Scotland's most powerful wind farm, capable of generating 50 megawatts of electricity.
ÊPermission was granted in May last year for another five turbines to be built next to the existing 20 300 foot windmills. Once in place, the wind farm will be able to produce 62.5MW.
ÊThe developers are also seeking the Scottish Executive's permission to build 'phase two' which would comprise a further 56 turbines. Borders councillors have already given their backing to the extension.
ÊThe technology used at Crystal Rig was the most advanced of its kind available when construction got underway in 2003. Each of the 60 40m blades Ñ three per windmill Ñ were manufactured in Denmark and shipped to the UK where they were transported to the remote site one by one under police escort due to their huge size. The Nordex towers were built in the Isle of Lewis.
ÊSome residents living near Crystal Rig believe the blade snapped because the conditions were too windy. Usually in such circumstances the turbines shutdown but villagers report seeing one of the windmills "spinning wildly" while the others were motionless.
ÊMs Knight continued: "Last week during the strong winds, the wind turbines at Crystal Rig were motionless for days. It may seem strange, but it was just too windy for them to work. Most people are aware that wind turbines don't operate when there is little or no wind - as on those cold, frosty days in winter when we need them most. What they may not know is that in strong winds over around 50-55 mph, turbines must be shut down for safety reasons."
ÊA spokesman for Natural Power, the agent for Fred Olsen Renewables which developed and now operates the wind farm, said: "There's a wind speed range within which the turbines will operate. Obviously, if the wind is not high enough they won't turn but there's also an issue when the wind speed is too high and it would not be safe for them to operate so they automatically close down. This happens in particularly gusty conditions and is simply a safety mechanism."
ÊThe Lammermuir Protection Group is presently fighting plans for another 62 turbine wind farm in the hills at Fallago Ridge, near Longformacus. The windmills proposed would be higher than those at Crystal Rig, reaching 410 feet (125 metres). Developers, North British Windpower, held public meetings in the area last month and claim the turbines will be well screened by surrounding hills.
ÊEnergy giant NPower put its plans for a 12 turbine wind farm just south of the Border at Tofthill, near Norham, on public display this week. Each of the windmills would generate three megawatts of electricity and reach over 400 feet (120 metres) high.