I note with interest the Agenda Column article by Jenny Hogan of Scottish Renewables (“Proper connections to grid needed to fulfil potential of green energy”, The Herald, January 2) and Colette Douglas Home’s column (“Halt onshore turbines that are blowing such an ill wind”, The Herald, January 6), on the continued widespread addition of onshore windfarms, particularly with regard to the possible impact of projected large-scale grid interconnections to Orkney.
Scottish Renewables and others have been strongly promoting the provision of new large-scale power cable links in the next few years from Orkney to connect with the high voltage grid at Dounreay to enable exports of up to 800MW (this is around one third the rating of Longannet) of renewables generation from Orkney.
Since large-scale generation from experimental wave and tidal research being conducted in Orkney is some way off there is a concern that large scale windfarm development on the islands is the hidden agenda of the various industry-supporting bodies, as it would be much cheaper to install them on land than offshore.
To put some figures to Ms Douglas Home’s concerns, let us, as an example, assume only half of the 800MW interlink capacity is given over to wind generation and realistically base the output performance figures on Whitelee windfarm at Fenwick, for which there is good data.
Whitelee output to the grid averages 30 per cent of its installed capacity annually and it generates 2Watts/square metre (which is regarded as “good” for a UK onshore site) . If we increase the likely wind turbine performance expectation in Orkney to 40 per cent (35 per cent has been achieved there in recent years) to allow for factors such as longer wind duration and higher average wind speeds, then in order to achieve 400MW annual average output an installed turbine capacity of 1000MW would be required.
If a similar rating of turbine to installed on Burgar Hill in Orkney were to be used, rated at 2.75MW,then a minimum of 364 turbines, each more than 100m tall ,would be required.
If the Orkney output averages were to be assumed as even higher, say close to 50 per cent more than Whitelee at 3Watts/sq metre, a minimum approximate land area requirement would be 133 sq kilometres (400/3).This is approaching one-third the total land area the largest island, at 174 sq km and would be approaching two and a half times the area of Whitelee.
Increasing the output rating of individual turbines would have little effect on the land area required as they would have to be spaced further apart but would also be taller.
Applications for large windfarms, given their scale,would be handled by the Scottish Government and there would be no local control over final decisions.
So, potentially, up to one-third of the main island under turbines would have to co-exist with Orkney’s £31m a year tourism industry.
Question is, could it? and at what cost to the residents?
D B Watson,