17th July 2018
Established 1872. Online since 1996.

Renewable juggernaut (James Mackenzie)

It was said, at the recent Dynamic Shetland conference, that Shetland would in future become “a huge hub” for wind, wave and tidal power. It’s perhaps worth examining this a little further.

According to present information, each Pelamis wave machine, with an overall length of 150m, is capable of generating 750kW of electricity. Hence the requirement for 14 machines to produce 10MW in the Aegir “wave farm”.

A wave farm of 40 machines would cover one square kilometre of the sea (according to Pelamis); this would then generate a maximum of 30 MW, or “power for 20,000 homes*”; 40MW would therefore require about 1.3 km²; and a 100MW farm would cover over 3.3 km².

If, as Bill Manson has postulated, these machines would eventually replace all the Viking turbines, at least 13 square kilometres would be required. That, a quick look at an Ordnance Survey map of Shetland reveals, would be a fair old chunk of the Burra Haaf, if that’s where the machines were to be situated. (I’ll only briefly mention, while thinking of the Grind of the Navir, the probability – rather than possibility – of Force 12 Atlantic storms . . .)

Then there’s the question of cables. If the electricity generated by the wave machines is AC, presumably they would all, severally or singly, be routed to the proposed converter station at Upper Kergord, in order to “plug in” to the HVDC interconnector (and this surely would apply to any other onshore or offshore installation requiring the interconnector).

Quite what this would mean in terms of disturbance to the seabed and to the landscape, already altered by the Viking Windfarm, I can’t fully imagine. I note, moreover, that Vattenfall’s managing director thinks that “one interconnector will not be enough”. Maybe one converter station won’t be enough either.

With all the glossy announcements made recently by Vattenfall, the SIC, Shetland Charitable Trust and the National Grid, not to mention Viking Energy’s proposal, on which the interconnector depends, I get the feeling Shetland is at risk of being flattened by a juggernaut, never mind that it has “RENEWABLE!” emblazoned like Christmas Coca-Cola all over it.

As was also said at the conference, there is “a great will” to make Viking and the interconnector happen – although I hadn’t noticed incontrovertible evidence of that locally.

Meanwhile relatively little seems to be proposed for reducing our own carbon footprint and reliance on fossil fuels. *This sort of equation is misleading. It simplistically implies that 20,000 homes would be free of fossil fuel power. Nothing could be further from the truth – unless all the homes were “off-grid”.

James Mackenzie
The Lea,
Tresta.    

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