I haven't seen any mention of this on usw:

http://news.bbc.co.uk/1/hi/england/c...re/7763816.stm

The date of the event seems to have been 2 December but reports are
not clear.

I am unable to find any realistic weather reports but presumably the
ice formed in stratus or fog with super-cooled water droplets at sub
zero temperatures (as happens with aircraft).

This sort of thing has happened countless times in the past, eg Emley
Moor, Yorkshi

http://en.wikipedia.org/wiki/Emley_M...itting_station

With blade speeds of wind turbines similar to that of wings of
(slowish) aircraft, icing in certain situations is inevitable and
should come as no great surprise. I had assumed, naively perhaps,
that blades of wind turbines would have de-icing systems, perhaps
electrical heating.

Jack

wrote in message
...
I haven't seen any mention of this on usw:

http://news.bbc.co.uk/1/hi/england/c...re/7763816.stm

The date of the event seems to have been 2 December but reports are
not clear.

I am unable to find any realistic weather reports but presumably the
ice formed in stratus or fog with super-cooled water droplets at sub
zero temperatures (as happens with aircraft).

This sort of thing has happened countless times in the past, eg Emley
Moor, Yorkshi

http://en.wikipedia.org/wiki/Emley_M...itting_station

With blade speeds of wind turbines similar to that of wings of
(slowish) aircraft,

Tip speed of some 125m Vestas turbines proposed for the village across the
way from us was 86 m/s (nearly 200mph).

icing in certain situations is inevitable and
should come as no great surprise.

It's well known hazard of wind turbines, though the manufacturers tend to
play it down. Not as hazardous as this Vestas turbine flying to pieces,
though...

http://uk.youtube.com/watch?v=kBYJul2ykZs

Wouldn't want to be downwind of that.

I had assumed, naively perhaps,
that blades of wind turbines would have de-icing systems, perhaps
electrical heating.

No, they don't generate enough electricity for that to be viable ;-)

Steve P

On 4 Dec, 18:25, "Steve Pardoe" wrote:

I said originally:
I had assumed, naively perhaps, that blades of wind turbines would have de-icing systems, perhaps electrical heating.

Steve replied
No, they don't generate enough electricity for that to be viable ;-)

You are joking I trust. Not enough electricity generated to look
after itself but enough (so they say) to power 50,000 homes!

Jack

On Thu, 4 Dec 2008 18:25:24 -0000, Steve Pardoe wrote:

I had assumed, naively perhaps, that blades of wind turbines would have
de-icing systems, perhaps electrical heating.

No, they don't generate enough electricity for that to be viable ;-)

Aye, the chances are that icing will be in calm freezing fog conditions so
the things won't be generating any power at all.

--
Cheers
Dave.

On 4 Dec, 19:13, "Jack wrote:
On 4 Dec, 18:25, "Steve Pardoe" wrote:
snip
I had assumed, naively perhaps, that blades of wind turbines would have de-icing systems, perhaps electrical heating.

They do have inbuilt spray jets (a bit like car windscreen washers) to
wash bugs and other rubbish off the blades, otherwise they reckon the
efficiency drops. Saw it demonstrated on a prog about wind turbines
on Channel 5 the other week. It surprised me as I thought that
squashed flies and bits of other things that had flown into them
woudn't have made much difference. Strange if they've done this and
then neglected the potentially catastrophic effects of icing.

Maybe they should just add a bit of de-icer to the washer bottles?

- Tom.

wrote in message
...
On 4 Dec, 18:25, "Steve Pardoe" wrote:

I said originally:
I had assumed, naively perhaps, that blades of wind turbines would have
de-icing systems, perhaps electrical heating.

Steve replied
No, they don't generate enough electricity for that to be viable ;-)

You are joking I trust. Not enough electricity generated to look
after itself but enough (so they say) to power 50,000 homes!

Well, sort of. My remark was of course tongue-in-cheek (though as Dave L
points out below, at times when icing is most likely there will be no
generation, and the passive turbine's control systems, telemetry etc are a
net drain on the grid) but the figure of "how many homes" is a statistical
favourite of wind power proponents since (a) it overlooks the fact that a
high proportion of electricity is used by industry and commerce, rather than
by homes; and (b) "power" (or energy) for homes is mainly for heating, and
that is rarely all-electric. Getting seriously off-topic here, but some
lobby groups have a cynical habit of confusing energy / power with
electricity.

SP

On 4 Dec, 19:24, "Dave Liquorice"
wrote:

Aye, the chances are that icing will be in calm freezing fog conditions so the things won't be generating any power at all.

That's not correct. Drawing parallels with aircraft (which I know far
more about than I do wind turbines), when an aircraft is parked on
the ground (ie, the wing/blade is not moving), hoar frost or snow
accumulation are the only significant forms of icing that can occur.
An aircraft on the ground never gets leading edge chunks of ice as
were so evident in that clip of the wind turbine icing. The movement
of an aircraft wing through supercooled cloud is precisely when ice
formation is at its most severe. Those bits of ice were perfect
examples of what can form on a "wing" in motion. The greatest ice
accumulation on a wind turbine blade will be when it is rotating.
Those blades would certainly not have been stationary in the recent
incident.

Jack

In article ,
says...

but the figure of "how many homes" is a statistical
favourite of wind power proponents since (a) it overlooks the fact that a
high proportion of electricity is used by industry and commerce, rather than
by homes;

About 27% of UK energy is used by the domestic sector. This figure is
falling.

and (b) "power" (or energy) for homes is mainly for heating, and
that is rarely all-electric.

Current wind turbine output in the UK is currently about 3000Mw which is
the energy consumption of about 1.6 million homes.

Any figure I have seen that relates to "number of homes" has always been
energy equivalent and not "current electricity consumption".


--
Alan LeHun

On Dec 4, 9:20*pm, "Jack )"
wrote:
On 4 Dec, 19:24, "Dave Liquorice"
wrote:

Aye, the chances are that icing will be in calm freezing fog conditions so the things won't be generating any power at all.

That's not correct. *Drawing parallels with aircraft (which I know far
more about than I do wind turbines), *when an aircraft is parked on
the ground (ie, the wing/blade is not moving), hoar frost or snow
accumulation are the only significant forms of icing that can occur.
An aircraft on the ground never gets leading edge chunks of ice as
were so evident in that clip of the wind turbine icing. * The movement
of an aircraft wing through supercooled cloud is precisely when ice
formation is at its most severe. *Those bits of ice were perfect
examples of what can form on a "wing" in motion. *The greatest ice
accumulation on a wind turbine blade will be when it is rotating.
Those blades would certainly not have been stationary in the recent
incident.

Talking about rotation. the length of the blade means that for half
its travels it will be below optimum height and wind forces on the
apparatus changes dramatically.

Any idea why the blades are not of the old fashioned cattle ranch /
sheep station, artesian-well type with most of the vanes concentrated
in the top of the tower most of the time?

To limit one's self to three blades, soaring in and out of pressure
bands seems a bit of a design flaw to me.

On Thu, 4 Dec 2008 13:20:24 -0800 (PST), Jack )
wrote:

Aye, the chances are that icing will be in calm freezing fog conditions
so the things won't be generating any power at all.

That's not correct.

I beg to differ, take a look at the pictures about half way down this
page:

http://www.howhill.com/weather/images/winter/index.html

That is freezing fog build up in fence wires (about 1/8" dia) and post on
the top of Hartside. Ok that location is at 1900' but shows that slowly
drifting freezing fog can accumulate to on surfaces to significant
amounts.

Those blades would certainly not have been stationary in the recent
incident.

Well not to throw the lumps of ice off into peoples gardens no but there
is nothing to say the ice didn't form with the blades stationary, then
flung off once the wind picked up a and the turbines started.

--
Cheers
Dave.