We can never have electricity completely from intermittent renewable sources

The wind farm set to be built in the Moray Firth (your report, 12 September) is in fact a joint French/spanish enterprise funded by the UK as a whole.

That it “will power one million homes” is, in my view, a bit of political puff rather than a technically informative description.

If we give the said wind farm a load factor of, say, 40 per cent, then on average it will provide a power output of about 400MW, which is less than 1 per cent of the current UK requirement .

The output of a wind turbine is proportional to the cube of wind speed so could be very erratic. Modern machines are, however, cleverly designed to give an acceptable steady generation rate for all wind speeds above the design value up to safety cut-off level. Below design speed is the problem – wind that is not there cannot be manufactured.

For example, at half design wind speed we would require eight times as many turbines to produce the desired power.

These machines at higher wind speeds could then produce far more power than required, which is equally unacceptable, so would have to be paid for not operating (so-called “restraint” payment). Wind power really requires “dispatchable” (controllable) back-up from a stored-energy source(s) such as hydro or gas.

To my understanding, the cost of this essential back-up (including “extra” turbines) is not included in the published construction and operational cost of wind energy, so it is not correct to compare this directly with nuclear (apples and oranges).

I think the above will again illustrate what I have repeatedly maintained – that there is no way we can ever have an electricity supply completely from inherently variable or intermittent renewable sources.

(DR) A MCCORMICK Kirkland Road, Terregles,

Dumfries Whoopee! We are all supposed to welcome another giant wind farm in our Moray Firth. Well, hard-pressed billpayers may soon beg to differ.

South Australia has also been duped by the wind industry and as a result has just achieved the highest power prices in the world. Because of its obsession with wind power and closure of baseload power stations, it has become the butt of international jokes.

These days, it’s almost impossible to read an article about South Australia’s economic misfortunes in which there is no mention of routine load-shedding and mass blackouts.

Its attempt to run on sunshine and breezes has left Australians with red faces and the highest power prices in the world.

To cap it all, the Greens’ founder, no less, Otto Georg Schily, has just declared Germany’s renewables policy an economic, social and ecological disaster. Why? Because it is a classic redistribution from the bottom up, forcing the poorest consumers to line the coffers of bloated energy companies. It has also cost more jobs than it ever created, and actually increased carbon emissions due to inefficiencies introduced into the system.

Turbines spew emissions during the manufacture, transportation, construction and maintenance of the machines and their uniquely demanding infrastructure.

A whole chapter on bird kill could also be written.

The second highest power prices? Another wind-powered contender, Denmark!

GEORGE HERRAGHTY Lothlorien, Lhanbryde, Elgin