A science view


A Science view.

Continued! The next riveting episode.

The comparative costs of generating electricity as calculated by the Royal Academy of Engineering, (Electrical Engineering) are:

Gas Turbine1
Pulverised coal1.4
Onshore wind2.5with standby
Offshore wind3.3with standby
Marine methods2.0

It is readily seen that that the cheapest means of electrical generation are the most intensive ones. The amount of energy per cubic metre in them is orders of magnitude greater than that found in the renewable sources.

This is true for all "renewables". The technology is aimed at deriving energy from dilute sources. Were it proposed to "farm" conventional agricultural crops on the same basis, would any farmer harvest a crop of, say, wheat, if his yield were to be even as high as 50% of normal, but of the order of 1%? This is the origin of the huge areas occupied by wind farms, which so often are generating only nugatory amounts of energy.

The frailties of wind generators does not stop there. Under high wind conditions, in other words generating at their design capacity, experience has shown that they have not infrequently to be isolated, and their output lost, because it cannot be accommodated in a controlled fashion by the Grid. A compensatory cost of this disconnection has been paid in recent cases at ten to twenty times the value of the electricity which would have been sold.

Not all the energy in the wind can be "used", the air behind the turbine would not be moving! There is a theoretical limit known as the Betz-Lanchester Limit, and this is a further restriction on wind power.

It has often been stated that, although intermittent, the "wind is always blowing somewhere". If that wind is blowing at below about ten miles per hour, it produces totally insignificant amounts of power. Such a situation occurred on 20 January 2011, when an area of high pressure covered the British Isles, the North Sea, extended into the Atlantic, most of Western Europe, and up into Norway. Over the whole of this area, only insignificant amounts of power were generated, for several days. In the depths of winter. Had wind power been a high proportion of planned generation, one hundred percent back-up of fossil fired generation would have been required. A slightly worse situation occurred on 1 September 2010.

So as well as constructing expensive wind farms, the equivalent generating capacity must be installed as back-up conventional power stations!!!! It is slightly surprising that the basic considerations of economics should not be brought into play at this point, especially as the Secretary of State has a First in PPE.

It is quite unclear whether or not the costs of the cabling carried out by the National Grid is included in the costs of wind energy. Suffice it to say that for every wind farm, small or large, it is likely that many more pylons are needed than the number of turbines connected. This consideration mitigates against the very large numbers of turbines, needed since the energy density is dilute.

To be continued!Richard Phillips

Topics: edie
Tags: | fashion | gas | offshore | renewables | technology | wind energy
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