In the Viking energy planning application addendum, the bean-counting element of Viking Energy has deemed that a development size of 457 megawatts (MW) is large enough to be economically viable. This would suggest Viking Energy has reached a compromise on the balance between “how big for profit” and “how big is acceptable” in its eyes. The next part of a windfarm turbine selection process should surely go out to the market and find the turbine that can deliver this power most effectively. Viking Energy seems determined to deliver the project using Siemens SWT 3.6MW turbines, of which they will require 127.
However, German turbine manufacturer Enercon currently offers its Enercon E-126 turbine at 7.5MW per turbine, more than double the power output of the Siemens unit. Enercon has earlier this year installed an in-land windfarm of 11 E-126 units at Estinnes in Belgium, with more units earmarked for a large onshore development in Markbygden in Sweden. Part of the E-126’s selling point is the storm control function which allows the turbine to keep producing energy up to wind speeds of 34m/s (force 11+) when the Siemens unit has shut down at 25m/s (force 9/10). The Enercon turbine is 35 per cent physically larger than the Siemens unit, but its use would allow the Viking Energy project to be reduced to 61 turbines. I’m sure that all involved, supporters and objectors, would agree that there is a world of difference in the impact of a 61 turbine development over a 127 turbine development. The advantages of the Enercon based development are as follows:
• Fewer turbines lead to less new roads and ground works resulting in less disruption to the habitat/ecology of Central Mainland;
• Fewer turbines would also give the potential for the project to be erected more quickly, leading to faster carbon and financial payback times;
• Fewer turbines make it easier for the developer to maintain maximal distance between settlements and the project boundaries and reduce the overall visual impact of the project;
• Fewer turbines mean the extensive work carried out into bird flight paths and habitats can be treated with more sensitivity in overall windfarm layout;
• Fewer turbines will potentially reduce the amount of shipping and road transportation required to build the windfarm.
There may be many more advantages and no doubt some drawbacks of using larger units, but I am at a loss as to why Viking Energy has restricted itself to the smaller turbine with the current application. For those who worry that Viking would just erect 127 of the 7.5MW turbines, the self-stated fundamental windfarm size of 457MW must be considered the maximum trade off on what the Central Mainland can hold and the size which Viking deems viable. As Gandhi once said: “All compromise is based on give and take, but there can be no give and take on fundamentals.”
In engineering, particularly where environmental considerations are being made, much is made of the term “Best Available Technology”. In my eyes, the Viking Energy proposal falls down as it fails to make use of the “Best Available Technology” currently out there.
Adam Priest CEng