At 04:19 PM 23/03/2012, you wrote:
On Fri, Mar 23, 2012 at 12:10:32PM +1000, Mike Borgelt wrote:
> >1.2GW of ultimate capacity offsets a gas-fired power station.
>
>
> I'm not sure that is quite correct. If you build a 1.2GW peak load
> gas fired power station you fire it up and it goes on line. The wind
> - not so much.
It's not as simple as that, because your 1.2GW peak load gas
fired power station occasionally goes offline too, so you need
to have a backup somewhere else.
Peak load stations aren't that large. I should have said 1.2GW of
peak capacity. Probably already spread around 3 or 4 power stations.
They normally nowadays require scheduled maintenance/inspection. The
gas turbines are usually the cores of jumbo jet engines and they
don't have huge in flight shut down rates.
One station may have several turbines.
Still better than wind.
So: Lets say your state has 6 GW of ultimate load, and you've
been servicing it at N+2 with 6 x 1.5GW power stations. Lets
also say your load is slowly increasing; and rewnewables are
on the table.
If you build another 1.5GW of wind power, your ultimate capacity
is then 7 x 1.5GW = 10.5GW, of which 7.5GW is reliably usable.
"Ah ha!" you say, "That last 1.5GW is wind, and sometimes the
wind doesn't blow, so you'll be screwed!" Yes, so that
effectively means the wind power is similar to an unreliable
power station. Sometimes it'll be offline and you'll have to
use your +1/+2 replacement supply.
If you've researched and planned your wind network well,
you can use well-understood probabilistic techniques to run
the numbers on how often that happens. You can also rely on
the fact that the wind rarely stops blowing everywhere at the
same time: Maybe when it's under duress your 1.5GW installation
is still good for 0.5GW 99.99% of the time.
From the figures the 1.5 GW of wind is on average good for around
0.5GW. A lot of the time it will be less than that.
In any case, what it really means is that you're taking
advantage of the fact that you've already built protection
capacity (the +2 in N+2) for fossil-fueled base load, so you
don't need to build it =again= for renewables; that makes
the renewables cheaper.
No it just made the gas fueled protection more expensive as it gets
lower utilisation in addition to the investment in the renewables. So
your power grid now costs more.
It all comes down to a numbers game, with failure probabilities
plugged in to a financial spreadsheet. If the climate
conditions are right, the failure probabilities are right,
and the component costs are right, you build wind instead of
fossil.
Funny how nobody did that until tax breaks(California), MRETs and the
CO2 madness.
If there's a carbon tax that makes that dirty power station
expensive to operate, you can avoid paying the tax by
investing dollars for network growth into renewables instead.
Then the tax becomes irrelevant because you're not paying
it, and you can live a happy life selling electricity just like
you always wanted.
Yeah you get to pay wind turbine manufacturers for spare parts
instead. Epoxy, carbon fiber, steel, bunker fuel to transport it,
diesel to install and maintain. Even Avtur as the offshore wind
turbine maintenance is sometimes done by helicopter.
> The installed wind capacity in SA appears to be twice the peak load
> generation capacity. I wonder what this does to the efficiency when
> the base load is throttled back to cope with wind on a good day?
SA's base load largely comes from gas, which is more amenable
to throttling than coal.
Open cycle is, combined cycle is more difficult.
SA also has a number of diesel-fired peaking power stations.
The emissions-per-watt for diesel are stratospheric compared
with gas and even a lot of coal; if large amounts of wind
generation capacity means the diesel peaking stations never
need to run, that sounds like a win to me if your success metric
is "emissions reduced."
> SA is connected to the national grid so quoting just SA is probably
> misleading.
Very true.
> >They tend to be lined up in rows. In terms of obstacles, I'm
> >not sure why they're any worse than a line of high-tension power
> >lines.
>
> The big ones are higher and I think the people who build power lines
> are environmentally sensitive enough not to put them on top of the
> ridge lines, whenever possible.
Are we talking about hazards to aviation or aesthetics?
Aesthetics.
I reckon they look graceful anyway. I don't find them an eyesore,
but meh.
> >The current "in thing" in Europe is to build the wind farm out at
> >sea just over the horizon, where the NIMBYs can't see it; and
> >run submarine high-voltage cables back to substations on land.
>
> As any ship owner about salt water corrosion.
You have a conductive path from the at-sea infrastructure back
to the land.
"Sacrificial anode."
Problem solved.
Read up on stress corrosion. Not "problem solved".
In any case, it's just another financial problem dealt with
by the bankers and insurance companies in their financial
modelling. "We're building this infrastructure. If it's
on land it'll cost $X and have a useful service life of Y
years. If it's built at sea it'll cost $A and have a useful
service life of B years." Plug the numbers into a financial
model and do whatever pops out.
> The big problem is that the actual generation stops when the sun
> sets.
That's ok, because the peak loads produced by air conditioners
(which is what drives the growth on Australia's grid) also
stop when the sun goes down.
The point is the low average power produced by solar. In 8800 hours
of operation(1 year) my 1.5kw peak solar produced 2000Kw-h. Just
south of 15% of peak on average. Peak is what drives the capital cost.
I've seen an analysis that says solar and air conditioning isn't such
a great fit as you think. Including a conversation with an
engineering consultant who did a study on that for the WA government
in the North west.
Utilities currently deal with the aircon problem by installing
"smart meters" which let them turn your air conditioner off
when the weather is hot and demand is high. Seems to me like
the time when you'd most want to be able to use it! I'd prefer
that the utilities jacked up my electricity bills to install
enough generation and transmission capacity to obviate the need
to do that. If solar provides a way forward, sign me up.
I'd prefer enough capacity got installed at the lowest cost. In Oz
that currently means coal, at least in Qld, NSW, Vic.
If it wasn't for the CO2 madness and resulting MRETs , carbon taxes,
tax subsidies etc we wouldn't be having this discussion and the
folks at Tehachapi wouldn't be having to fight a wind farm.
Mike
Borgelt Instruments - design & manufacture of quality soaring
instrumentation since 1978
www.borgeltinstruments.com
tel: 07 4635 5784 overseas: int+61-7-4635 5784
mob: 042835 5784 : int+61-42835 5784
P O Box 4607, Toowoomba East, QLD 4350, Australia
_______________________________________________
Aus-soaring mailing list
Aus-soaring@lists.internode.on.net
To check or change subscription details, visit:
http://lists.internode.on.net/mailman/listinfo/aus-soaring
