Monday, 2 April 2012

"The wind is always blowing somewhere"

Read or heard that before? It's the trite and ill-defined "argument" used by proponents of wind power. "Wind is variable" they intone, but "the wind is always blowing somewhere", and will provide sufficient power for "all our needs". The first part of the claim is undoubtedly true; the wind is indeed "always blowing somewhere", but unfortunately for them, and for the rest of us too, it depends entirely on where that "somewhere" is, and a few other important factors. Let me tell you a story.

The time is the future, some twenty years hence. I propose a mythical small country Aeolia, named after Aeolus, the Greek god of the winds, a son of Poseidon, appropriately enough the god of the sea, over which most winds originate. Aeolia is a large island off the coast of Europe, and has large wind turbines spread evenly round the coast, and across the hillier parts. The entire country is crossed by high-voltage power lines linking the turbines to the centres of population. Tourists don't visit Aeolia in droves as they used to. The Aeolian government ascribes it to the high exchange rate and visa controls. They omit to mention the 60% increase in tourism in nearby Francia, which has 100% of its power supplied by nuclear power stations, and an almost total absence of large white towers (apart from the Eiffel Tower, now painted white to reflect solar radiation and so cool their capital, Paris). The Aeolians closed their nuclear stations years ago; their energy minister called nuclear power "unproven and dangerous technology" while in opposition, and before being handed the "poisoned chalice" of office. Francia's neighbour Germania, closed theirs because they were apparently worried about tsunami inundation, in a large country with little ocean shoreline

When the prevailing south-westerly wind blows steadily over Aeolia, all is well. The turbines to the west and south run at about 2/3 rated output, Those on the hills about the same, but the remainder progressively less towards the east and north; especially the east, which is for the most part in the lee of hills, The Aeolians aren't stupid, they have allowed for that in the number of turbines built. When the south-westerlies abate a little, the west and south produce a little less power, as do the hill-top ones; those in the extreme north and east produce almost none. The Aeolians aren't stupid, they have allowed for that in the number of turbines built.

Occasionally, a meteorological phenomenon known as a "blocking high" (large area of high pressure) with little or no wind beneath covers most of the country, and the turbines are stilled. The Aeolians aren't stupid, they have allowed for that by importing power from Francia, through an enormous underwater cable; that country generates more power than it needs, and exports about 25% of it. Other countries around Francia have adopted the "Aeolia model" and get all of their power, most of the time, from wind. They also have large cables to France to import surplus power when the wind dies away, and so all is well. Happy days!

The wind doesn't always waft over Aeolia from the southwest. It almost as often comes from the other points of the compass, and doesn't maintain its direction nor strength as well as wind from the southwest. The Aeolians aren't stupid, they have allowed for that in the number of turbines built.

Very occasionally, though the Aeolians can't remember the last time it happened, a very large  "blocking high" covers most of western Europe. If that were to happen, Aeolia and Francia's other neighbours would be requesting power from Francia, but Francia has only 25% of its power to export, even if all the nuclear stations run flat out. It can't supply the "top-up" needs of but one of its neighbours, or a fraction of their needs to all. The Aeolians aren't stupid, they have allowed for that by building large gas-fired power stations that spend most of their time idling at the ready, burning gas just to maintain that state. The gas is imported, even though almost the entire country is sitting on vast reserves of shale-gas. It remains untouched since their energy minister called "fracking" (using high-pressure water to force out the gas, used since the 1950s) "untried technology".

The northern part of the Aeolian archipelago is the small independent country of Scotia, which went all out for both political and energy independence almost two decades ago. They have a number of wind and tidal stations, but import 60% (on average) of their power as gas and electricity from across the sea, from Norwegia, which is 100% hydro-electric, and whose citizens luckily have a soft spot for the Scots, who they maintain are really Norwegian anyway.

The story doesn't end there, but since the the Aeolians aren't stupid, and have built sufficient turbines to meet their power needs most of the time, how may would that be, and how many would they need if the wind was blowing in just 25% of their country, meaning the wind really was "always blowing somewhere" in their country? As we've seem the "always blowing somewhere" might well mean far away.

Taking the ideal "south-westerly" or "Goldilocks" (it's just right) scenario, the number of turbines would have to be increased countrywide by about 25 % if the wind drops a bit. If it drops a bit in the west and south, it drops a lot more in the sheltered north and east; some turbines would be below threshold speed and produce nothing. If the "always blowing somewhere" area with "a bit less wind" was only half or even 25% of the country, that already increased number of turbines would have to be multiplied by two or four. This means the total must be as many as five times the "Goldilocks" number. Chinese manufacturers would be building new turbine factories faster than Aeolia and other "it's a breeze" countries could erect new turbines.

This analysis is, of course completely ignoring the inherent minute-to-minute, hour-to-hour variability of the wind; that can be partially "evened out" by each "farm" having a large battery attached which can be charged using excess power, and discharged to fill the troughs in output. But, and it's a big but, that capacity has to be quite large to even out more than minute-to-minute variability, and these batteries are expensive. They wouldn't be a "nice to have", they'd be a necessity. Gas-powered backup can't be ramped up and down on even an hour-to-hour basis, more like over four to eight hours. Wind forecasts would have to be almost continuous and very reliable.

Short-term variability between large areas is a bigger problem, one that hasn't been addressed anywhere worldwide, to my knowledge. My position on wind is this - large-scale generation and integration is very difficult. Wind won't work on its own, and even with power storage and gas-fired backup is very difficult and expensive to manage 24 hours a day. Wind would be ideal for remote and isolated communities, villages and farms, especially in the undeveloped world; small-scale battery storage is viable and not very expensive. Combined with solar (photo-electric or hot water) systems and integrated storage they could and would provide electric power and heating for people who now have nothing but wood and dried cow-dung or limited supplies of expensive (for them) diesel and petrol. Their "half a loaf" would be welcomed, and I'm sure they could organise themselves around a variable supply. In my opinion wind (and solar) could lift millions, if not billions out of poverty, improve their health, pump clean water from wells (especially using excess off-peak power), and even supply small factory units. I'd gladly see some of my taxes funding such projects, and I'm sure many others would too.

World political leaders tell us of their "visions" of cheap, clean energy for their countries. They never mention the magic word "reliable".

This post was, in part, inspired by a "conversation" with Peter Lang, who describes himself as
... a retired geologist and engineer with 40 years experience on a wide range of energy projects throughout the world, including managing energy R&D and providing policy advice for government and opposition. His experience includes: coal, oil, gas, hydro, geothermal, nuclear power plants, nuclear waste disposal, and a wide range of energy end use management projects. 
I hope to write several other less "mythological" posts about the realities of "renewable energy" soon.

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