Kyoto – A Perspective (Part 26)

Posted on Thu 05/22/2008 by

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WIND POWER (Part 1)

Waymart Wind Farm Pennsylvania.
This photograph shows five of the forty three wind towers along the ridge line at Moosic Mountain near Scranton PA, part of the Waymart Wind Energy Center.Each of the towers is approximately the same height as the Statue Of Liberty, and generates 1.5MW of power. I varied the contrast slightly in the photograph so the blades can be seen standing out a little more against the brightness of the sky. 

Photograph courtesy of FPL Energy.

Contrary to the opinion that electricity generated from renewable sources is cheap, and in all probability, free forever, the opposite is in fact the case. We have seen that power generated by solar means is quite expensive, and here we will see that power generated by the wind is also not cheap.

Why is that?
The cost of the construction of the generators themselves.

Similarly with nuclear power plants and solar power plants, the huge capital cost is at the front end.

Let’s look at how this system works then. I think we can all recall seeing photographs of one of these towers in our time. They are, in the main, tall towers with the large three bladed fan spinning slowly in the breeze. After years of engineering, it has been found that these large slowly spinning three bladed fans are the most efficient method of operation. The large spinning blades on the tall towers are the most visible, but all the work is done in the nacelle behind the blades. As you might imagine, the blades can spin at differing speeds with variable wind strength, so this motion has to be translated to a set speed to drive the generator. This is achieved with what is called a constant speed drive, (CSD) in effect a gearbox similar to the one on your car but instead of varying the speed through the range of acceleration as with your car, the speed of the rotating blades has to kept to an absolute constant.

This then drives the generator also housed within the nacelle. In the early days, power generated was quite small really, fully dependent upon the actual size of the generator itself. This CSD is infinitely more complex than the automatic gearbox in your car, considering that is the single most complex part of your car, so the complexity of the CSD adds considerably to the cost of the Plant, which again has to be small by its very nature to fit in the nacelle which cannot be too heavy.

If you can remember back to the coal fired plant and the nuclear plant, the generator was huge, in the vicinity of some 30 feet long, 12 feet across and weighing up to a hundred tons, so something that size is totally out of the question atop the huge tower counterbalanced only by the blades. Hence, the generators can only be so big, and because of that they can only generate so much power.

The larger ones have become fairly efficient now and can generate as much as 2.5 MW power at their maximum, some more.

Remember how we have the coal fired, nuclear and hydro plants running at a constantly driven high speed to produce a carefully regulated supply of power we call baseload power, well, plants using renewables like solar cannot be used for baseload plants, as the Sunlight is variable, and so is the wind in this case. The reliability of power generation in the case of wind power averages between 20% and 40%, and the efficiency rating of the newer ones is around 35%.

The cost of the production of the electricity is as I mentioned, the huge capital cost at the front end, with just maintenance and upkeep as ongoing costs. The average cost is around $1000 per Kilowatt, and that works out to be around two million dollars for a 2MW nacelle unit.

So then, keeping this in mind, let’s replace one large 2000MW coal fired plant with an equivalent wind generated collection of units.

If each unit produces 2MW, then we’ll need 1,000 of them. There’s two billion dollars. Keep in mind the efficiency rating of 35%, so that degrades that total power to a third, so you’ll need three times that to produce an equivalent power. Now we’re looking at six billion dollars, and three thousand of those large rotating fans.

That 6 billion is just for the units. We then have construct the infrastructure to get the power from the fans and nacelle units to the grid, the transformers, the transmission lines, and the costs now begin to mount.

This photograph shows three of the twenty wind towers at the Magrath Wind Farm in Alberta Canada. 

Photograph by Chuck Szmurlo and is a CreativeCommons photograph.

Three thousand towers with rotating blades. Sounds like it could be done. Consider then the new wind farm planned for Cape Cod. It will have 130 towers covering an area of around 25 square miles. In this case you will need around twenty of these farms the same size. The farm at Altamont Pass, has more fans, but these are early generation fans producing only a fraction of the power of these new ones.

So twenty farms of around 25 square miles or so. Now you can see the cost mounting, especially for the infrastructure, spread over vast areas as opposed to the one plant in the one place.

Something also that may not enter your thoughts is this.
The Gamesa plant in Pennsylvania is producing these wind plant structures and is currently scaled up and producing two nacelle units per day. At that rate, 10 per working week, around 500 per year, that’s six years just to produce the structures for this system here.

So, at six billion dollars just for the nacelles and six years to construct them, it now compares favourably in every respect to a Nuclear plant.
Now, keep in mind that something on this scale is just to replace one large coal fired baseload plant.

Perhaps now, you can see the enormity of the task, the cost, the scope, and the infrastructure needed on a scale not imagined so far.

So, when people moot the idea that wind is a viable alternative, it may just be, but the cost will be enormous and will have to be borne in the long run by the consumer.

Incidentally, that plant planned for offshore in the Nantucket Sound off Cape Cod has been costed at around $900 million. So the figures I quoted earlier seem conservative by nature. At this end of the costing scale, then the theoretical replacement proposal might cost in the vicinity of 15 to 20 billion dollars, and that makes it way more expensive than any comparable nuclear plant worst case scenario. The cost here would be mainly for the infrastructure, because it’s not like you can just put a couple of hundred wind towers in the same place occupied by a coal fired power plant it is mooted to replace.

The land has to be carefully selected in an area where there is good wind, usually at higher elevations. Then you have to have access to a large swathe of that land and we’re talking miles here and into double figures at that, so you’re probably looking at hundreds of square miles for each wind farm, and there needs to be twenty or more of them. Then, you have to construct the transmission lines and all the other infrastructure. This will take time, and an immense amount of money.

Now you can see just why renewable forms of power will only ever make up a tiny portion of the overall electrical power pie chart. Governments will inevitably see it as too expensive, private enterprise will see it as having to wait too long for any realistic return, and most important of all, the public themselves when confronted with the fact that is going to cost them considerably more for their power, then they will also protest at the idea.
So, as much as it actually looks like a win win situation, it will most probably strike out.

Wind farm power plants will be boutique suppliers on a small scale, and only in limited areas.

KPPSTony