Wind power. Did Bob Dylan get it right: “…. the answer is blowing in the wind”?
Ten years ago the debate on wind power was polarised by green sentiment in favour of Dylan’s early classic. But when we probe deeper comes the realisation that his 1974 masterpiece, “Idiot Wind”, is far the more prescient.
We now know that wind power is hugely expensive, saves trivial amounts of carbon dioxide, if any, and does nothing to secure our energy supply.
So why are 32 generators – each weighing 70 tonnes and sitting on 100m tall towers – being proposed in the clear- felled remnants of a Welsh forest?
The basic reason is that the wind does not blow all the time, and as a result a 3MW machine on a Welsh hillside will struggle to make an annual average power of one third of that – enough to power 500 electric kettles.
When the wind dies down, other back-up generators will have to take up the slack.
The wind power industry would tell us the slack will be taken up by other windmills elsewhere because the “wind is always blowing somewhere” in UK.
If wind turbines were spread evenly across the UK, that might just work. But the clustered layout of UK’s turbines – a block in Wales and the Irish Sea, another array in the North Sea – guarantees it won’t.
As a work-around, the industry would have us spend vast sums, through our electricity bills, on a high voltage DC cable network across Europe.
Pigs might fly.
Batteries? More squadrons.
So the UK will have to build its own back-up generators to bridge that gap, and to cover those long periods of high pressure when there is no wind at all anywhere, like the three snowy weeks of December 2010.
“Not dark yet”. Yes Bob. But 2013 keeps popping up as the year when engineers expect electricity supply to fall short of demand.
We’ll be asked to use power only when the wind blows. If wind power developers had been required to build their own back-up plants, we would not be facing blackouts.
Back-up plants must be switched off and on as fast as the wind power goes up and down. That rules out using nuclear and coal-fired power stations.
Pumped-storage capacity like that at Dinorwig copes with rapid surges in demand for just a few minutes and is then exhausted.
(To be fair Professor Mackay’s book “Without Hot Air” identifies new pumped storage sites in North Wales and Scotland for a big expansion of pumped storage, but costs and funding are not considered).
That leaves gas-fired plants. The best way to burn gas to make electricity is in a “combined cycle” gas turbine.
Yet these machines do not operate effectively at less than full power – expensive gas is wasted.
So we are left with open-cycle gas turbines, resembling an aircraft jet engine geared to a generator.
These are perfect for switching on when the wind fails, and off when it picks up. But no company wants to build them, because they waste that valuable exhaust heat and would be inoperative for about half their life.
In Germany, which is years ahead of UK with wind power, the actual CO2 saving has proved to be just 6% of the turbines’ rated power.
The Germans were not so daft as to site turbines in forests. But in Wales the Government’s TAN8 planning legislation, promoted by Carwyn Jones, earmarked forestry land for turbines.
That mistake wipes out the carbon dioxide savings completely. Trees have to be felled out to a radius of hundreds of metres to prevent loss of wind speeds – and a reduction in profits.
This removes that last 6% of carbon saving. As far as climate change goes, wind turbines in forests are ineffective.
“All along the watchtower”. A watchtower in the forest? Yes, for the next time a wind turbine catches fire, as one did at Tir Mostyn.
The planned turbines are no more than 100m from the nearest trees, and will be surrounded by brash from felling, all highly inflammable. It is astonishing that fire risk to forest dwellers has not been assessed by developers, nor the Welsh Government.
“Thunder on the mountain”. Mr Dylan, that’s not quite right, wind turbine noise is not exactly thunder.
It’s called aerodynamic noise and is caused by the blades being driven forcefully into slow or turbulent air.
Noise assessment protocol uses data on turbine noise provided by manufacturers (yes, really!) from a turbine in the midst of an airfield where wind flows bear no resemblance to those in a forest.
When it became clear several years ago that the green credentials of wind power do not survive scientific scrutiny, the watchword for the embattled promoters of wind became “energy security”.
Really? The open cycle gas-turbines that can mirror the wind’s fluctuations burn gas one third less efficiently than the combined cycle turbines.
And don’t forget the extra cost of pylon connections to remote wind sites, and the destruction of landscape.
So here is Bob’s message to Rt Hon Carwyn Jones, instigator of the Welsh Government’s TAN8 planning edict that targets wind power into forests.
“…You have many contacts among the lumberjacks to get you facts when someone attacks your imagination… But something is happening here and you don’t know what it is do you, Mr Jones?”
Prof Cobbold is a retired Liverpool University academic who lives near Derwen.
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