jbeckton wrote:kolm wrote:(a) energies are not all alike,
(b) net energy calculations are not always the only thing that matters,
(c) people won't act 'rational' (maximize energy flow over lifespan of humanity), but what economists call 'rational' (maximize short-time earnings).
Is a wind generated watt different than a coal generated watt as far as the
end user is concerned?
The end user will notice the difference on his electricity bill, so yes, they are different for him. For the power generator, they are even more different. The wind generated watthour is generated when the wind blows; the coal generated watthour is generated when the operator wants it to be generated. That is a huge difference in practice. The learning curve on how to deal with this just started; e.g., the theory of pricing intermittend electric power is in its infancy. Power suppliers will learn to deal better with this than today, which will reflect on the bill, but I don't expect miracles.
However, I rather wanted to refer to FF vs. electricity. A heap of coal is something entirely different from a tank of gasoline, which is in turn very different from electric power. They have different applications and values.
If you wanted to maximise the really-long-term energy flow from renewables with FF, it might even make sense to use them for building huge mountains in high-rainfall areas for running water power. Nobody will do this, however, because in a shorter time window the investment would essentially appear as a complete loss.
kolm wrote:The problem is that they are not very reliable. (Ask the danes about it.) People don't want unreliable power supply, so power suppliers need backups, either by call options on power or by back-up plants.
Coal and nuclear provide base load and will for the forseeable future. Wind and solar will supplement.
Well, but you need load balance, and coal and nuclear do not want to be used for load balance. This might be a solvable problem, but the solution does not seem obvious or easy.
kolm wrote:First of all, Parson type steam turbine couples work at about 40%, not 33%, and they are used in the power industry if it pays off economically. In NPP, you usually don't want many things that can jam, because down-time and maintenance costs you dearly, hence you usually accept lower efficiency than theoretically achievable. Second, even 33% is not too far from carnot efficiency, hence I do not understand what you mean by 'not efficient at all'.
Forget Parson. Whats the efficiency of the average steam turbine generator in the US?
About 33%.
Well, that could be due to one of three possible causes:
(a) Engineers are stupid idiots in the US.
(b) US Power supply managers do not care about economics of their plants.
(c) This is about the right rate for
cost-efficient generation given today's conditions.
Your guess?
Not too far off from carnot? Lets see-
TH=1005 degF =813.71K
TL= 95 degF =308.15K
TH is rather 630 K for Boiled Water reactors; in coal plant, you do have 800 Kelvin steam, but the usable range is up to TL = 380 K (steam starts to condense). However, I'm not picky, you can run with those numbers if you like.
Yeah, good call 33% is close to 62%
My result is more like 49% carnot, but I'll gladly go with yours:
That's a question of perspective, ain't it? Is 1/2 of the absolute best the universe can offer (no matter what science and technology is used) far off or pretty close? I think it's not that far away; we came from 6% to this with a lot of high-level engineering.
And mind you, the original claim was that NPP/CPP are working with incredibly poor efficiency. I rather think that they are working with amazingly high efficiency, given the challenges involved. You build a better
economical plant, you can spit on the 33%.
kolm wrote:Where does nuclear energy suck air out of the atmosphere?
At its ventilation openings. Cool air is used to cool cooling water.
Sure, but where does the steam
burn oxygen which was the point I was making?
I did not see that you made this point. This might be my error, but I just saw a question; usually questions are stated because one is interested in the answer.
kolm wrote:It uses a nuclear reaction to boil water, the rest is no different from a coal plant.
Hell yes it is. If you have a leakage in the cooling water containment of the coal plant, you can make a guesstimate how long you can run this thing and go on; in the NPP, you have to shut down immediately and file an incident report.
And that happens all the time right?
I know an engineer who rather regularly (every two-three moths) was called into the Coal PP to estimate how many tons of water the newest leakage would lose per second, and if they can run it until 10 pm, when it was cheapest to take it from grid and fix the leakage. This was regular business at a rather high-level and well-maintained Power supplier. So, yes, it happens rather often in a coal plant.
The NPP designs are trying to minimize such coincidences, with consequences for the steam turbine design part.
But of course you're right in stating that the fundamental principle of generation at this point is the same.