Idle Wind Turbines

Mike O'Dell mo at
Wed Oct 10 11:05:33 CDT 2012

yes indeedy - cheap NatGas has dealt a body-blow
to all the alternative energy sources

the coal miners in WV are all spun-up about the
bottom falling out of the coal market. they are looking
for someone to blame but in fact, it's NatGas.

In most cases, it is far cheaper to install new gas turbine
gensets and just mothball large coal-fired generation
than it is to refit large boilers for multi-fuel or 
do a full NatGas conversion. The turbines are cheaper
to buy, the fuel is cheaper, and the operating costs
are less.  true, it takes more boxes to get a gigawatt
of generation, but that's not all bad. losing one gas turbine
out of 20 is not nearly as bad as losing one steam turbine
out of 4. plus all the grief of water treatment, etc, etc, etc.
the gas turbines can also be pushed further into the distribution
fabric so the transmission losses are smaller and the load flows
can benefit as well. the new silencing stacks are good enough
that siting in suburban substations is not out of the question,
providing better compartmentation in the case of large outages
like ice storms and the like. and of course, they are completely 
automatic, designed for lights-out, hands-off operation. 

that's why being a coal miner today in West Virginia sucks even
more than usual.

as for wind farms, even before NatGas dropped through the floor,
China was simply buying the markets. the Chinese gubmint simply
commanded their big banks to supply gobs and gobs of cash to 
their wind and solar industries. they now have a large surplus
of both solar cell and solar panel fabrication facilities, much
of which is idle (far in excess of demand) and it looks like it
could turn into their very own toxic asset fiasco. wind has also
been largely bought the same way, although not with as much 
market share as in solar. there are other players besides the
Chinese sources and there are still some farms under construction
here in the US. 

the biggest problem with most existing wind turbines is that they
have big, heavy, expensive, and fragile gearboxes which transform
the slow but powerful motion of the huge rotor into the many
hundreds of rpm needed to drive an AC generator that must sync
with the rest of the grid. the turbines were sold as having a
service life of 30-40 years, but unfortunately, the gearboxes
last maybe 5 years if you are lucky - less if you aren't.
again, if you are lucky, when the gearbox dies its horrible,
grinding death when one of the 23 sets of bearings siezes,
all the pieces and the precious bodily fluids stay inside the
casing.  if you are not lucky, pieces leave making holes in the case,
the superheated hydraulic oil is exposed to oxygen, and you
have a nacelle fire. maybe the suppression system snuffs it,
maybe not. in the mean time, if the main rotor shaft is intact,
the rotor likely overspeeds, or the big bearings siezed which
brought it to a very sudden stop. either case usually results
in big pieces of fiberglass flying and falling from 300 feet.

most of these machines are in the 1-2 megawatt capacity range.
the next generation of "direct drive" machines are in the 3-5 megawatt
range and the alternator turns the same speed as the rotor.
it has lots and lots of poles which is then bulk rectified to
high-voltage DC and then a big inverter does with *big* transistors
what the gearbox tried to do with iron - make 60Hz AC perfectly
matched to the grid.

none of this fixes the cheapness of NatGas, but the NatGas producers
aren't at all happy with the prices either, so a significant
fraction of the wells are being cut back from production so they
can get the price back up to where the gas from a well can at least
cover the costs of maintaining the well and keeping it producing.
there are a lot of wells which are running at a negative margin
these days.


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