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When windmills go bad

Posted: Thu Jan 08, 2009 5:30 am
by AccordGuy
Before you all rush out and buy 3MW wind turbines, have a look at this video of one gone AWOL in Denmark last year... ... tions.html

Posted: Thu Jan 08, 2009 12:30 pm
by lemmiwinks
I've seen that one before, quite entertaining :) I would dispute that very impartial :roll: website's assertion that a braking mechanism failed. On the forum where I first saw that video it was thought probable that the feathering mechanism failed which seems far more likely to me as the likelyhood of successfully braking a wind turbine of that size (especially long term) seems close to nil.

Posted: Thu Jan 08, 2009 11:37 pm
by AccordGuy
Yeah, he starts out negative and then goes off the deep end in the later pages which are just a personal rage against some specific politicians in Holland.

Having said that, the original pro-wind web site that they aped the name of (to annoy them) is equally opposite in painting a overly rosey picture with no reference to the downsides of wind power at this scale.

It's very thin on answers. It acknowledges that upgrades to the grid infrastructure will be required to integrate wind power farms but doesn't say how.

It acknowledges that wind power is variable (but skims over just how variable) and then says that there's no problem with the variability affecting load scheduling because a) the variations are covered by primary generation response capability and b) that wind power accounts for an insignificant proportion of generating capacity.

This is all wrong. Control centres have prior knowledge of all large swings in load - even to the point of looking at the TV schedules to guess that when a 10 million viewer rated soap drama has it's half-way commercial break in the evening, 7 million viewers will go out and "put the kettle on". It's less of a problem these days as we have more channels and the days when 20m people routinely watched the most popular soap drama on one of the 3 TV stations have gone. Still, large industrial loads are required to call in before starting up.

The UK has the Dinorwig hydro power storage station of 1.7GW but this is for short notice load balancing only. It uses off-peak grid power to pump the water up the mountain to a reservoir so that later at steep gradient demand surges it can release that energy back to the grid when primary generation cannot ramp that quickly. Dinorwig can go from zero to 1.7GW in 16 seconds and can be spun up, synchronised and on-line with 1.3GW in 12 seconds. The problem is that it can deliver this for only 5 hours and takes 7 hours to recharge (pump all the water back up the hill, using 1.6GW of grid power).

The stated plan for Europe is to massively expand wind power (amongst other unreliable renewable sources) generation to 20% of demand. This negates their argument that wind power does not form a significant proportion of generating capacity so the variations are negligible.

If we really were to install 20% of UK demand in wind power, that would be just short of 8GW capacity (2,654 3MW turbines). Dinorwig is the largest hydro-storage project in Europe and is designed only to cope with short term load variations. It is designed to allow planned starting and stopping of primary generating capacity in bulk. Dinorwig can quickly supply a few minutes of peak demand over the running primary capacity and then later either spare primary capacity can be used to recharge it or, if necessary, another chunk of primary capacity can be spun up to aid with recharging. The difference is that this generator can be started, run for 7 hours at full load and then stopped. Steam powered turbines (coal, gas, oil, nuclear) only run most efficiently when run at near full load.

Dinorwig can also cater for sudden catastrophic failure of a single power station (unplanned outages) but only long enough for an alternate power station to be spun up and take its place. It cannot cope with a variable load and an unpredictable primary source. The swings in load gradient will be greatly magnified (worst case is a "coffee break" at the same time as a drop in the wind).

We're lucky though... Wales is a mountainous and persistently wet place. Holland is flat.

The wind generating proponents aren't considering the large scale picture. They install these 3MW generators all over the place and how you transport the power to where it's needed and how you iron out the irregularities in its delivery are "somebody else's problems".

Everyone who has run an off-grid system knows that you need backup generation for your wind turbine or solar array. Sharkey's and my solar systems are a backup to the grid. We use solar as much as possible but there are still times when we have to hook up the batteries to the grid charger to prevent the lead acid batteries rotting through over-discharge in winter or bad weather.

Solar and wind have a valuable place in offsetting use of primary generation but they cannot be counted on as reliable primary sources.

Posted: Fri Jan 09, 2009 9:49 am
by lemmiwinks
Very interesting AccordGuy. While I think wind is great, I agree that it's certainly far from perfect. Though I do think that more wind farms are better, after all apart from the horrific initial cost it's very cheap.

I saw this program when it aired in 2007 and found it very interesting, especially the solar trough stuff funded by Vinod Khosla (founder of Sun Microsystems). I think it might be the way forward. ... /video.htm

Then there's sliver cells. I want some! :o ... lls_hi.asx

Posted: Fri Jan 09, 2009 2:07 pm
by AccordGuy
As if to pour more petrol on the fire, there was a news report tonight on TV about a wind farm in Lincolnshire where the rumours are that a low flying UFO crashed into a wind turbine, ripping one blade off and bending another on it.

Alternatively, the thing could have just been badly manufactured and it fell apart by itself :roll:

Picking up on a point you made... these things are pretty expensive to run as well as build, requiring maintenance to (or at least inspection of) the gears and blade controls. Granted, they don't need much maintenance but if you have thousands of the things dotted all over the countryside on remote hilltops (or worse still, out at sea) and you have to get a man up a 100m tower on each one, the costs soon add up. At least a big steam turbine station is a bunch of big machines all on the ground in one building near a road...

Plus, if these things break at this rate (two that I know of last year and this one in a farm that has only been operational since April 2008) then the maintenance costs for failed units could be very high indeed.

The company responsible for installing these 20 turbines in a field (where nobody got hurt by this weeks failure) has also built a similar turbine in the middle of the office park that I sometimes have to work in at Reading. I'll be nervous working there on stormy days :shock:

Both of those programmes were really interesting. My case was made again by the controller of the California power grid. He said they could only go with the aggressive target of wind power because they had a mix of base load (primary) generation that could take up the variations in the wind generation output. Geothermal is a great renewable source that works well as a base load source.

The concentrator PV cell is also interesting but impractical for domestic use. Having Sun tracking parabolic mirrors is not viable for mounting on a house in urban areas.

The heat storage technology that Khosla mentioned was intriguing but he didn't explain anything about it beyond "It can store maybe 24 hours worth of solar generated steam energy".

The sliver cell is a cool idea but will probably be overtaken this year by much cheaper continuous process printing or sputter deposition (as used for high grade metal magnetic video tapes) types that can make amorphous cells by the 100 metre roll using modified existing manufacturing technologies. The slivers still have to be cut from a silicon wafer that takes a lot of energy to grow in the first place.

Also, even if you cut it really fine with a laser and etching, you are still wasting maybe as much as 25% of the wafer by etching it away to make the gaps between the slivers and in the film you saw a big area around the edge of the central square of slivers that was also not used (although this could possibly be re-melted to make new wafers).

Amorphous cells are less efficient but use a tiny fraction of the silicon that crystalline ones do.