On wind turbines…

March 8, 2014 by  
Filed under Wind Energy Tips

Given the parlous state of Eskom and the electricity network, it is natural for citizens to wonder about alternative means of electricity production.

This is also quite topical considering Eskom has awarded something like 1,600MW of renewable power contracts, recently. Mostly wind, but a bit of solar too.

Of course, I have heard some absolute clangers on this subject recently. First prize goes to the muppet who suggested that solar farms (photo-voltaics, or PV) generate during daylight hours, but also be used to charge some large batteries, that can then be used to run through the night.

The other oft talked about technology is wind turbines. Indeed, many people have noticed the massive development of wind farms in recent times, especially in the Eastern Cape.

Allow me to say something unpopular. Wind turbines are the proverbial plaster, when you’ve just had an arm amputated. As an engineer working for a supplier to that industry, I have worked on a number of wind farm projects. And it is my goal today to tell you why these turbines are a rubbish idea.

First, let’s get the subjective stuff out of the way. To me, they are ugly. Other people think they’re just pretty windmills. I would far rather cast my gaze over pristine Eastern Cape countryside, stretching to the sea in the distance, than be faced with 50 lots of whirling blades.

Secondly, they are noisy. This is not something you’d notice from your car on the N2. But the residents of places like Jeffrey’s Bay and Cape St Francis are going to find out soon enough, that a farm of 50 or more turbines, all at full chat, is enough to disturb the sleep.

Third, those spinning blades may seem to be turning quite gently, but because they’re so long (45m from hub to blade tip, typically), even to achieve a very modest rotational speed (revolutions-per-minute), the tips are moving through the air at hundreds of km/h, almost the speed of sound. And at those speeds, the local bird life does not stand a chance. Wind turbines absolutely decimate local populations.

I guess that all of the above could be forgiven, if they were providing a useful quantum of power to our grid. Here’s the thing though… each turbine can provide a maximum of 2.5 to 3MW. A collector of ten units is thus good for (say) 25MW. Compared against an Eskom shortfall of 2,000MW, that is peanuts.

But that’s not all. A typical large windfarm of around 150MW capacity, occupies an enormous tract of land. Very similar in fact, to that occupied by a coal-fired power station. Yet the coal installation can deliver 3,600MW. In other words, wind has an energy density, in terms of the land it occupies, only 1/25th that of coal.

And lastly, when it comes to wind power, ironically, it needs the grid to be there, in order to generate. Yes, wind turbines are unable to supply a small “island” of load, unless the greater grid is present and stable first. This is due to the technology used to manufacture the generators inside the turbine nacelles.

So, the next time someone suggests that wind turbines are the solution to the energy crisis, you can tell them that they’re just plain wrong. Wind turbines only serve to keep the emotional environmentalists happy. The rational, realistic environmentalists are going to suggest something else. Something safe, clean and with an extremely high energy density. Nuclear.

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