Sunday, 27 March 2011

On Wind Power In Taiwan

I like wind turbines. What I mean is I like the way they look; they have an aesthetic appeal. As an industrial scale renewable energy source, however, I'm skeptical...
"Electricity production grew from 84.1 TWh in 1989 to 229.7 TWh in 2009, an average annual increase of 5.15%. Of the total electricity production in 2009, Taipower's hydro power comprised 3.01%, thermal power 44.09% (coal shared 28.00%, oil 2.67%, LNG 13.43%), nuclear power 18.10%, wind power 0.16%, cogeneration 17.29%, and IPP 17.35%."
Those figures are quoted from page 17 of the Energy Statistical Data Handbook (available as pdf download from the website) from the Ministry Of Economic Affairs' Energy Bureau. Attend to that figure for wind power - 0.16% - and then consider this:
"Taipower has installed 162 onshore wind turbines over the past decade, almost the nation’s maximum capacity, Huang said, adding that space for offshore wind turbines was limited... If nuclear energy is to be replaced by wind power... the country needs to install a total of 12,000 wind turbines, Huang said."
That's the vice chairman of Taiwan Power Co, Huang Hsien-chang (黃憲章) quoted toward the back end of Saturday morning's headline article in the Taipei Times. Now according to the EU-funded project WindFacts, the expected costs for a new offshore wind farm are currently in the range of 2.0 to 2.2 million €/MW, or about 84 million NT$/MW. So at those numbers how much would it actually cost to replace the existing power capcity of nuclear power in Taiwan with wind power? Well 18.10% of 229.7 TWh is 41.5 TWh, and 41.5 TWh over a year would require... (some arithmetic later) ... a capacity of just shy of about 4700 MW. At a capital cost of NT$84 million per MW, the total capital cost for a wind farm of that size would be somewhere in the region of NT$400 billion, not counting the various problems that may contribute to cost overruns of course (like location issues and externalities).

Huang claimed it would take 12,000 wind turbines to replace nuclear energy in Taiwan. Now that depends, because those would be small turbines (i.e. 390KW output capacity), and I know that many companies are already producing very large turbines capable of 7 MW and more, which would almost certainly make them cheaper and more efficient. The Enercon E-126 turbine, which I believe is currently the world's largest in operation, is capable of a 7 MW power output; a wind farm comprising eleven of them was built in Estiennes in Belgium in 2009-2010 at a cost of 6.2 million Euros, or just over NT$257 million. Assuming those numbers are good, we can divide that total cost by the number of turbines installed (11) and we get a cost of about NT$23 million per turbine. In order to get to a capacity of 4,700 MW from these 7 MW turbines, 671 of them would have to be built, which would cost about NT$15.5 billion - and even if the real number would be quite a few billion higher, that is an unquestionably massive improvement on the NT$400 billion calculated using the EU's Windfacts numbers for offshore windfarms.

However, the Estiennes wind farm in Belgium is onshore. The rotor diameter of the E-126 turbines is 126m, and it seems that a lot of space is required between each turbine. I can't seem to find any numbers for this, but - and I readily admit this is from looking at pictures - let's call it a radius of 500m per turbine (the real number will be either more or less of course, but it seems a reasonably accurate guess). Using that number of a 500m distance between turbines, to construct 671 such turbines would require an open land area of 335 square kilometres. That is huge - that is significantly larger than Taipei City (272 square kilometers) and more than twice the size of either Kaohsiung City (154 square kilometers) or Taichung City (163 square kilometers). (Correction: 671 turbines would require an area of over 100 square kilometres - see comments). So, assuming such a windfarm was to be undertaken by Taipower at the behest of the government, then whatever savings might be made by building such mega-turbines would almost certainly be wiped out by land costs alone - unless of course a strategy of land theft is endorsed, and it wouldn't surprise me if many environmentalists actually would endorse that (which would validate my use of the terms "eco-soviet" or "eco-fascist").

Yet let's not get carried away. Limited construction of such mega-turbines on land near existing science-industrial parks in Tainan and Hsinchu might not be a bad idea if captial costs could be kept to within a few hundred million NT$, since a principle advantage would be substantially lower costs than a nuclear plant and a greater efficiency in the transport of electricity from the turbines through a grid to the actual plant buildings. However, this would only become potentially viable if the government in Taipei were to withdraw itself from the subsidization of industrial energy. As a libertarian I would cheer a move like that - so long as it was not accompanied by punitive taxation measures on CO2 emissions - but I'm not holding my breath for the State to get out of the energy business any time soon.

Incidentally, anyone who wants to fact-check my numbers or offer better data or other criticisms is welcome to do so...


  1. On turbine spacing, you need something like 5 to 10 turbine diameters between each turbine, so the number of 500m you've given is not far out, given the turbine rotor diameter of 126m.

    On the other hand I'm not sure how you came to your calculation of land area. I don't think it's the maximum area for that number of rotors, but it could probably be optimized.

    For example, by placing each rotor on the coast, you could theoretically reduce the land area to a corridor measuring 335.5km long by 63m wide - a "mere" 21sqkm. However, this obviously assumes that we have stable cliff geography stretching for 335.5km on which I can build a series of wind turbines.

    By taking a "cell" of nine wind turbines, you can fit nine of them into a square that occupies 1 square km measuring base to base. In practice, you'd need to eat up more area outside of the turbine towers, so let's add another 100 m to each end: 1.2 x 1.2km = 1.44sqkm.

    You'd need 74.55 of these mini farms to meet your 671 turbine quota, that's 107.36 square km.

    It's still a huge land area. Order-of-magnitude wise, we're still talking about a city in terms of area.

    The thing is, people don't respond well to numbers. I think people need to see pictures of these things to really understand. A picture of Taiwan, with a shaded area and a wind turbine picture to denote how much space would be needed for a wind farm of this scale would be the perfect tool for showing people the feasibility of wind power. Or solar power.

  2. On my area calculation - yes and no. Yes it's way off the mark since it mistakenly assumes a half sqkm per turbine (I'm blaming it on staying up well after bedtime).

    On the other hand, one important thing I neglected to mention is that, for a 4,700 MW set of wind turbines, you're probably not going to turn much more than 30% of that power into energy and so the comparison to nuclear is still a bit of a joke. To correct that and turn the equivalent of 90% of a 4,700 MW capacity into energy (i.e. 4230 MW), the turbine quota would have to be revised upward threefold (to 2014 turbines) at a new capacity of 14,100 MW*.

    Stipulating to your multiple "cell" arrangement of nine turbines per sqkm, there would need to be 224 of these cells rather than 74. And going with the 1.44sqkm per cell figure, that's a land area of nearly 323sqkm - which just happens to be very much closer to my original (mistaken) figure of 335sqkm!

    At any rate, whether the land area is 100+ or 300+ you're right on the point about images. The thing to do would be to map these areas in terms of different land zones across Taiwan in addition to some rough indication of possible engineering cost ranges per zone.

    The best place to build in theory would surely be the plains outside the science parks in Tainan and Hsinchu along with some locations as close to Taipei, Taichung and Kaohsiung as possible and then a few dotted on down the western planes. These locations would presumably be great in terms of bringing down efficiency losses through grid transfer, but on the sort of scale we're talking about I'm not even sure there'd be enough of them in terms of typical wind speeds and land quality to complete the project to that sort of scale. And that's without even considering the issue of land prices (or land theft) and costs.

    *And even these numbers might not be right since there is apparently a giant windfarm being constructed in Sweden that will use >1000 turbines over 500sqkm.


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