53 to 54 percent at perfect load for combined cycle now. 42 percent for coal fired steam plants, again at perfect loading. None of these plants get to stay at perfect loading very much of the time, but they try.
J. Clarke wrote: ....
Oh, I agree wholeheartedly it's a seemingly asinine thing to do, but w/ current politics in charge it appears it will be either that or...well, just what, specifically??? There doesn't appear to be a substitute of the magnitude required in the short term to simply quit.
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Well, the 42% of a current supercritical boiler isn't what I'd have interpreted as "common and built years ago"...is about right for last 10 years or so, agreed.
The only real hassle w/ the combined cycle is that it's a misuse of NG for baseload generation imo. Good choice for load following, etc., ...
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When enough people figure out that the choices are to pay ludicrous electric rates, freeze to death in the dark, or build nukes, the greenies will be told to go pound sand.
J. Clarke wrote: ...
I used to think so; any more I'm not so sure it'll just not be roll-over time... :(
I've said numerous times that as the current spate of applications for new units comes up for licensing hearings we'll learn real soon now how serious the C-sequestration people are for actually accomplishing something as opposed to simply being obstructionists. I have my opinion what we'll see of them; hopefully to be shown it's wrong...
Some seqestering is being used to increase production of oil fields.
Mark
Yes, there are some byproduct uses but I think will remain quite small volumes relative to the product stream (product being a waste in this case).
I guess one could clean it up and use it for carbonation, too... :)
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Mark
Robatoy wrote: ...
I never did find the eng'g drawings online for Bull Run and my TN buddies are busy and I told 'em to not waste their time if didn't either know it or have it directly at hand...
So, I did a very rudimentary minimum wall thickness calculation for seamless tubing based on the ASME B31.1 criterion based on allowable stress and got a number otoo 4" for 30" nominal diameter, 3500 psi working pressure w/ steel derated to 12000 psi for temperature. I don't think that's _way_ out of line, but it's certainly not a design calculation.
Higher tensile strength values would reduce that at about an 80% proportionally to the ratio of strengths. I didn'tfind the applicable ASME table for temperature factors online and it's one I don't have at hand (I'm a nuc-e, not mech, ... need cross-sections? I got those or shielding data or ... :) ) so reduced another 20% based on a subcritical system calculation. OTOH, one might reasonably expect better alloys which would be higher at temperature, to compensate. So, as is it's a guesstimate. Better data would be nice but only tables and/or piping calculators I found were all for purchase, none were online modules like the sagulator the likes of which I was hoping I might find...
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Don't know if it applies here, but Engineer's Edge has become a routine stop for me as a free resource:
time. Looking, I found a pressure vessel calculator that gives somewhat higher values at similar conditions but it has no references to the basis for the computation, unfortunately, so I can't tell what's causing them. Clearly it's not the same as B31.1 but doesn't reference either a Standard nor the criterion behind it so can't tell.
Unfortunately, they don't have a link to the pertinent ASME Standard, either...so, useful site for much but didn't help me out on this particular sidelight trivia quest...it got me to wondering in that I really don't know what the dimensions actually are, myself. I've got the TVA design book for a couple of the older plants we did some technology demonstration projects at but they're not of any help for the supercritical units, unfortunately.
I asked:
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Got no answers, but onward and upward.
This is a commitment that can be described as serious.
As luck would have it, a lot of the oil is in the desert.
Wonder if this wind farm is also in the desert?
Lew
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Might be nice if they could be switched to fans to suck the smog out of California.
The already have them. It is my understanding that the big windmills have to be started with electricty from the grid. All they would have to do is run them when there is no wind and a lot of smog
I think there was a Beverly Hillbilliees episode that dealt with that very proposition wherein investors approached Jed with the idea of drilling a large shaft/tunnel through one of the mountains above L.A. to include giant fans that would suck the smog out of the L.A. basin. Having advised Jed they had investment commitments for all the major components save the tunnel Jed asked, "Well, who gets the shaft?"
Dave in Texas
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There's only one way to answer the above initial question and that is by comparison of actual operating costs under the rules in effect at the moment. By those, other than for installed hydro, coal is clear overall cost-effective winner. Nuclear is also in the neighborhood as well.
Wind is for the local grid about a 1.8x multiplier over coal/nuclear; I've seen claims it's much closer than that to conventional but don't know how they get the figures; the above is based on the bus charge for our local REC for our costs to the supplying generators.
One problem w/ wind is that even here in SW KS known for being one of windiest places in the US the wind doesn't blow all the time, particularly less in Aug and Feb, the two peak months and at night when lose thermal heating effects that contribute. The Gray County farm has averaged only about a 40% capacity factor since it went online in 2002 or so based on their reported generation to DOE/EIA that I looked at a year or so ago. The maximum monthly average was just over 50% for a couple of months while the two slack months were in the mid-20% range. That means need 2.5X extra installed capacity to make up the target generation on average and 5X in weak months. That's a real construction burden to do more than augment conventional technologies.
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I keep trying to reconcile the what we know about nuclear powered satellites and the size of the behemoths we seem bent on building on the ground. Even the small units that power subs and aircraft carriers. Why do these power plants always have to be so big and unwieldy? I don't want to go as far as suggesting 'Neighbourhood Black Power Boxes' but....(I understand there would be security issues but that is not why the big nukes are as big as they are.)
"Nuclear powered satellites" aren't powered by reactors (though it has been done, it gets messy). They use the heat from decaying material to generate electricity via what are essentially thermocouples (known as Radioisotope Thermal Generators). They produce very little power and are *expensive* so only used where the sun don't shine. Nothing in Earth orbit needs or uses them.
Nuclear reactors themselves aren't all that large. It's all the support stuff around them.
nuke plants are large because of the generation size, and containment (accidents).
subs don't have 'large' plants because they skip a lot of the safety and containment bits. if they get a meltdown, it just goes out the bottom of the hull.
chaniarts wrote: ...
Not really. The prime reason is they're highly enriched, much higher power density (and much smaller total power output/reactor) than commercial power reactors.
They have design bases that are much more stringent in terms of load swing, maneuvering rates, ability to restart immediately after shutdown, etc., owing to the demands placed upon them by combat readiness. Hence, they're much more expensive per MW also.
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