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Assumption 1; CO2 controls the Earth's termaretupe.Assumption 2; more CO2 warms the Earth, which will be a disaster.Assumption 3; no matter what it costs, we must build generators that don't emit CO2 (except nuclear, hydro).Assumption 4; Wind turbines will get cheaper as they get bigger and more are built.Assumption 5; the electricity from wind turbines reduces CO2 emissions by that equivalent amount.Assumption 6; (not really relevant to this discussion) the more wind turbines the less the fluctuation in output. None of these have been proven. Leaving aside 1 & 2 which are matters of faith, and No. 3 which merely shows that the Greens aren't very logical (or want to have their cake and to eat it too) we have 3 that I would like to comment on.No.4 - As turbines get bigger the tip speed of the blade increases, causing high load on the blade. This means either they must rotate more slowly and lose efficiency, or that special high strength materials have to be used in their construction. These will push up the cost. Switching from hand layup of unsat. polyester to autoclaving of anhydride cured epoxy will at least double the cost of raw materials, and the change of process even more. Check out the cost of carbon fibre versus glass fibre also (and C fibre is brittle so vibration fatigue becomes important).No.5 comment by Honza; I'm afraid it isn't quite that simple. For a start some OC turbines would have to be kept as spinning reserve i.e. rotating at synchronous speed ready to be "ramped up" to load. This emits CO2 for no electricity generated. CCGT can start as OC, but that would take an hour from a cold start. The fastest startup for CCGT is 3 hours minimum. You can run CCGT at lower loads, but their CO2 efficiency suffers.i.e. run a CCGT at 40% and your CO2 goes up to 600-640kg per MWh. Also you must have very efficient OCGT in your system, a figure of 700 is more likely, and 760 if using oil.There is another factor; wind turbines use power from the grid. When the wind doesn't blow strongly enough for generation, the control system in the turbine is still monitoring, using the yaw motor to move the nacelle to the right direction and, in the larger machines there are smaller motors to keep the power shaft rotating to prevent sagging. (Same as for steam turbines in coal fired stations which are rotated at ~3 rpm when off line).The figures for CO2 saved by wind turbines are very hard to find. At best the savings are about 25% of that assumed. No.6 is just plain wrong. Several studies have shown that widely separated ( 1600 km in 2 cases) turbines DON'T operate independently, i.e. if one lot is generating little power, the other lot won't help output.
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(VISITOR) AUTHOR'S NAME
Amina
MESSAGE TIMESTAMP
17 december 2014, 21:11:40
AUTHOR'S IP LOGGED
62.210.78.179
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