Off shore turbines (Was Re: Potential dumpster diving opportunity).

[Mike O'Dell]

because of the water depth where the big offshore wind turbine towers
will be placed, they are going to be "semi-submersible"
like the big deep-water drilling platforms.

the towers will extend some significant fraction of their
above-the-water height down into the water. They
will be counterweighted with sea water and static ballast in a sailboat.
they will then be anchored to the sea floor with multiple huge anchors
("Bruce" type, most likely) again, just like the semi-submersible drilling
platforms. enough mass under water, they are surprisingly stable
because of the mass of the counterweight as well as the sail area
of the underwater structure.

the Norwegians were the first to build semi-submersible towers and
put them out for testing.  I don't think any are in production yet, but
several projects have committed to the approach because of the
test results. The Norwegian yards build a lot of the deep-water platforms
and they expect a lot of business building the semi-submersible towers.
at least one project has started construction of the blade plant on the 
shore
so the blades can be moved right off the line onto barges to move to
the pylons.

the cranes to install those blades are non-trivial engineering in their
own right. the off-shore cranes must cope with wind conditions that
the shore-side cranes would simply call it quits for the day.

     -mo




On 2/8/13 4:04 PM, Andre Kesteloot wrote:
> On 2/8/2013 12:18 PM, Mike O'Dell wrote:
>>
>> i was just reading about the next generation off-shore turbines which 
>> are targeting
>> 10 Megawatts per turbine. The blades for those suckers are 100 METERS 
>> long,
>> so the diameter of the blade swept area is 200 meters.
> anything that is mechanical suffers wear-and-tear, hence needs 
> maintenance.
> Offshore structures (I known, I installed and commissioned a pirate TV 
> station built on an oil-drilling rig) are fraught with problems.
> I am not certain that the advocates of off-shore turbines always 
> include the long-term maintenance cost in their sales-pitch ...
> André
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