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Heat Wave Shuts Down Alabama Reactor
mdsolar writes "In a first for the US, one of three nuclear reactors at the Browns Ferry nuclear plant in Alabama has been shut down because the Tennessee River is too hot to provide adequate cooling for the waste heat produced by the reactor. This is happening as the TVA faces its highest demand for power ever, reports the Houston Chronicle. This effect has been seen in Europe in the past, forcing reduced generation, but the US has until now been immune to the problem. The TVA will buy power elsewhere and impose higher rates, blaming reduced river flow as a result of drought."
As for a while, they were planning to use one engineer's idea of cooling it with ice cold beer.
In Soviet Russia, overheating nuclear reactor shuts down YOU!
Knowledge is how to play a game, intelligence is how to win, wisdom is knowing what game to play.
>but the US has, until now, been immune to the problem.
no, not immune. it just hasn't happend until now.
I work at a nuclear power plant. We have a limit for the temperature of the river downstream of our returned cooling water for environmental reasons, not reasons related to the power generation process. I suspect the TVA has a similar requirement.
I noted from the nrc website (www.nrc.gov) that their other reactors are operating at reduced load, which is what our reactors must do to limit the heat input into the river.
So this is nothing remarkable.
Why not just run the river through a refrigerator to cool it down? After all, you can generate the electricity for the refrigerator in the plant.
(I'd patent the idea, but the patent office has a silly rule regarding perpetual motion machines that gets in the way...)
Help! I'm a slashdot refugee.
This is not that unusual for power plants. Some coal fired units are off as well, for example Dynegy's Wabash River is currently experiencing similar problems. Obviously this hurts everyone (the company loses generation during times when wholesale power prices are high and, if load gets too high, the consumer might experience brown outs or black outs). This problem will likely get worse as well as global warming takes hold.
They are already red states. Might as well make them glowing red.
It would give a whole new meaning to Louisiana Hot Sauce...
To anyone arguing that Climate Change is actually a good thing - in general, it isn't, and this is an example. Especially in the US, our entire infrastructure, agriculture and manufacturing is built and created under the assumption that things will stay the same. Pipelines in Alaska were built under the assumption that permafrost was, well, permanent. Nuclear reactors were built under the assumption that the temperature changes of rivers are known and won't change. Levies are built with certain assumptions about local rainfall. Agriculture is built on certain assumptions about the local weather.
Yes, we can adapt to it, but it's an expensive proposition. All the stuff about cities flooding, people dying and malaria becoming the new bane of the US is extreme cases being blown up to make good news stories. It's the accumulation of small things like this that'll hurt.
Those who can, do. Those who can't, sue.
It ain't about problems with the cooling itself, for that the rivers would need to be far hotter. The problem is enviromental, if you add extra heat to an already warm river you risk that it rises to the point were you destroy the eco-system. Simply put, the fishes get cooked and the algea grow out of control.
This is considered to be a bad thing.
MMO Quests are like orgasms:
You may solo them, I prefer them in a group.
The cooling problem is a result of TVA's interest in building more reactors. Browns Ferry is now operating with two reactors instead of three because they recently added a reactor. They are also planning on adding a reactor upstream at Watts Bar http://www.tva.gov/news/releases/julysep07/wbu2.ht m adding to the heat load on the Tennessee River. So, next time, they may have to take two Browns Ferry reactors off line at seasonal peak demand. This makes electricity more expensive because it requires buying rather than selling electricity when it is most expensive.
s -selling-solar.html
But, the fairly natural solution to the problem, reducing summer demand through net metering of customer generated solar power, a solution being implemented in 41 states and DC, is hampered in the TVA service territory by TVA's net metering policy: http://www.tva.gov/purpa/net_metering.htm which is a billing period-by-billing period policy rather than an annual carryover policy used in net metering states. Adopting a reasonable net metering policy would allow TVA to become a summer time peak demand power exporter and gain by arbitrage, reducing the risk of higher overall rates it is building for itself by not paying attention to the capacity of the river system to handle the 60% of wasted energy nuclear power generation creates.
--
Power when you want it most: http://mdsolar.blogspot.com/2007/01/slashdot-user
Why not just figure out a way to turn waste heat into energy to avoid heating the river up unnecessarily?
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
They need to be engineered in parallel with a large reservoir
to provide a more stable source of cooling water.
The sign of a trend (upward or downward) matters. However, so does the MAGNITUDE of the trend, and the magnitude of temperature increase has gone up over the past few decades.
-b.
The Carnot cycle determines the theoretical maximum efficency of heat transfer. There are basic topside limits (In a pipe that's uncapped at the end going into the river, water can't be hotter than 100 C or it's not water anymore). Practically, all the heat exchange systems, even ones with molten sodium and such, have absolute thermal upper limits. These are usually above the sensible ecological limits, so engineers normally design for the more restrictive, environmentally safe limits.
But, the difference between cold and hot determines maximum efficiency possible even for a theoretically perfect system. If the top stays fixed, and the low temperature base goes up, the cycle HAS to become less efficient. This applies to all power-plants, not just nuclear ones. A coal plant that uses a river for cooling, a sterling cycle solar engine, or the internal combustion engine under the hood of your car, all become less efficient from this effect. While this power-plant has to stay shut down, every single car driving across the south and southwest is running at lower efficiency than usual, and wasting more gasoline.
Who is John Cabal?
Interesting in the article that the journalist doesn't include power generated by hydroelectric dams as renewable energy...
"TVA gets about 60 percent of its electricity from coal-fired power plants, 30 percent from nuclear plants and 10 percent from its 29 hydroelectric dams. Renewable energy sources such as wind and solar account for less than 1 percent."
Any idea why that might be? Political slant? ignorance?
Umm, I mean the water flows through the dam, it goes out to sea, it evaporates, and it rains back up in the mountains and comes through the dam again. Seems pretty renewable to me.... at least some of it is coming back up through that cycle if not all...
To give you an example. Someone starts screaming in public that they are going to kill you. They show up at your house with a large handgun and force the door. A couple minutes later, several shots are heard. The man runs out of your house without the handgun. You are found dead and the coroner determines the hour of your death to be around the time the man with the handgun showed up at your door. Noone else has shown up that day other than the man with the handgun. The bullets which have blasted what little brains you have out the back of your head are determined to come from the gun lying on the floor, which is the same one brought in by the man who forced his way into your house.
Now, given all this, you would apparently parrot the rule saying "Correlation is not causation".
I feel like death on a soda cracker.
Spelling matters.
That would also get the lard off of so many of us as well. Drive down health care costs. "Eliminate nuclear and coal power in favor of solar and wind power, and replace the stupid cars with bikes. Eventually the global warming will take care of itself and we won't need as much energy as air conditioning will no longer be needed. The added bonus would be less obesity in the world."
Now of course there is the minor problem of having a tornado by the tail near a nuclear reactor -- but aside from the fact that you can channel hot water quite a distance economically, the hydrodynamic models (computational and scale) indicate that the base of the vortex can, indeed, be contained in a location. The real problem is that this system hasn't been scaled up to a sufficient size -- in an appropriately isolated test area -- to validate the models to the degree required by public safety.
Seastead this.
Heat rises. Vertical turbines in the nuclear reactor towers might work if they could figure out how to circulate the heated water around inside the towers?
Still waiting on Serviscope_minor to wake up to fucking reality and realize that Jessica Price isn't going to fuck him.
It would sure be nice if more people had a better grasp of basic scientific principles, wouldn't it?
To heat domestic water, space heating and even to power adsorption chillers which can reduce AC requirements. Even coal power stations can hit 88% efficient.
t s.html
... Well you decide for yourself.
http://www.helsinginenergia.fi/en/tuotanto/benefi
US power stations are still only 40% efficient because
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The bicycle as a commuter vehicle works only under ideal conditions and only for the young and fit. You won't be taking a bicycle into Buffalo, NY in mid-winter. You won't be taking a bicycle into Houston, TX in mid-summer.
Especially considering the coming energy crunch.
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Interesting in the article that the journalist doesn't include power generated by hydroelectric dams as renewable energy...
Journalists ain't scientists, and scientists ain't journalists... in general. So if you're reading something in the news that's science related, don't count on it being accurate.
When our name is on the back of your car, we're behind you all the way!
Heat is disorganized motion, right? Atoms and molecules just bumping around any which way. If you want organized motion, which is useful energy -- such as an organized motion of electrons, a.k.a. electricity -- then you have to get that heat motion organized, flowing in one direction.
You do this by making the heat flow from one place to another. But here's the catch: you need a source and a sink to have a flow. The hot reactor core is the source. The river is the sink. Heat flows from the former to the latter, and the turbines, in essence, dip a "paddlewheel" into that current.
If you get rid of the sink, nothing flows, your "paddlewheel" doesn't turn, and you get no useful energy.
I would hope you would parrot the rule saying "Correlation is not causation", or rather I would hope that any other alternatives are also investigated (like suicide or possibly even that a third person did the shooting) sure Its unlikely, but its worth the effort to prevent a miscarriage of justice.
How this applies to climate change though isn't all that clear. We are sure that temperatures are rising, we are fairly sure that they will continue to rise, and we are inclined to believe that the changes are brought about by our own actions. In that scenario we need to tackle what is apparent whilst also making sure that there are no other explanations.
Much like you would arrest the potential murderer in your first example immediately and then discount any other possibilities, we should be looking to tackle climate change (by addressing the issues we believe cause it) until we know more one way or the other, what we should not do is close down any other avenues of investigation until we are sure that we have all the information we need, after all if something else turns out to be the culprit (regardless of how unlikely that is) we may need to take some other action, something we couldn't do if we stopped looking.
Yeah the big question to me is what other options are there for cooling a power plant other than using river water, and are they more sustainable / resilient to climate change? I don't think that underground cooling would be sufficient. I looked at how some of the desert plants operate and they too use running water - from the sewage lines of "nearby" cities, which is treated before use in the plant and then returned for reuse.
Seeing as how nuclear is really the only option we have for decreasing our power-plant C02 output on a large scale, and that low water levels, and increasing water temperature are only going to become more frequent (especially if more plants are using them for cooling) that seems like a pretty important issue. It may already be solved - this is just the first I have heard of it.
Sorry, just a compulsion. Here's a more readable summary:
"In a first for the US, one of three reactors at the Browns Ferry nuclear plant in Alabama has been shut down because the Tennessee River is too hot to provide adequate cooling. This is happening as the TVA faces its highest ever demand for power, reports the Houston Chronicle. This has occurred in Europe in the past, forcing reduced generation. The TVA will buy power elsewhere and impose higher rates, blaming reduced river flow as a result of drought."
It's really amazing that these basic principals of thermodynamics were all figured out in the early 1800s, but almost 200 years later people still don't get it.
Um...isn't this the nature of time, life, existence, et cetera? Things change. Even if there were no such thing as man-made global warming, the Sun would still vary its output, the continents would continue to drift, evolution would continue to produce new and interesting diseases, et cetera and so forth.
What do we call individuals who run their lives under the assumption that things will always stay the same? That they'll never get old or sick, that their job will never disappear or their skills become obsolete? "Intelligent" doesn't come to mind.
Besides, consider the advice you give people bemoaning the fact that their life has changed (e.g. they had to get a new job, now they have a baby and can't party all night, et cetera). We tell them, hey, change is an opportunity. So it is with climate change, natural or man-made. It's not a lot different than new and disruptive technology (cf. the RIAA and the Internet). Some folks will lose, yes. But others, especially if they're flexible and intelligent, will win.
Personally, I think the lesson to be learned from global warming (from whatever cause it stems) is not to resolve to hold back the tide, this time or next time. That's just futile. The Earth will always be producing some new surprise or other. The general solution algorithm is not to try to put fingers in every dike that develops cracks. There aren't enough fingers, and too many dikes. The trick, as individuals and as a species, is to think creatively and adapt. Otherwise, we're just dinosaurs wondering what that flash in the sky was, and why the swamp is drying up steadily.
No, dear, I did not. You are struggling with the Second Law of Thermodynamics, which — in the form most applicable to the situation — is spelled as "It is impossible to convert heat completely into work."
My point was, that a better-engineered reactor would convert more energy into work. This increase of the work/heat ratio is a purely engineering problem — the only "fundamental limit of thermodynamics" is that the ratio be below 1...
In Soviet Washington the swamp drains you.
They don't "run off waste heat." They run off waste heat plus a cooler atmosphere into which they can allow heat to flow.
All you need to use the "waste" heat being dumped into the river is to find something significantly cooler than the river. Then you can set up a heat engine between the river and your cold thing and generate power.
The problem of finding something just lying around in Alabama that is significantly colder than the local river is left as an exercise for the student.
They have electricity in Alabama?!
There's already a simple, monstrously expensive system for doing just that:
District heating
District heating is the process by which the low-exergy waste heat (and even some medium-exergy heat, when a higher thermal/electrical generation ratio is favored) is delivered to end users. Usually this involves transferring the heat from the plant's steam/water circuits via a heat exchanger to a water circuit that goes directly to the customer's home. Steam was used in older systems, and can still be found in New York's (from the 1880's, IIRC). From there, the heat is transfered via a heat exchanger to the customer's hot-water heater and radiator systems. In Scandinavia and Eastern Europe, this system is widely deployed. Besides minimizing the environmental impact of thermal power plants (coal, nuclear, biomass) on rivers and water tables (in areas without sufficient surface water), it also hinders the expansion of electric and gas heating--transmission mediums with highly volatile prices and supplies. In addition, it's also an adaptable technology. A district heating net doesn't care how the water gets hot, so long as it gets hot enough. If your district heating plant goes bork, the net can be fed by emergency thermal or electric boilers. If your natural gas supplier goes bork, well, let's hope that Angolan LNG tanker comes quickly.
Most of the US has a climate that requires large amounts of cooling in the summer and large amounts of heating in the winter, with low electrical demand in fall and spring. While a much less deployed technology--and, then, usually only in large apartment buildings and office blocks--district cooling can also be utilized by using the waste heat to run an evaporative cooler which then cools a circuit of near-freezing water. The details of this are too much for my poor brain to recite, but, in short, instead of throwing that ~30% of your plant's heat input which converted to electricity at the problem, you can use some of the ~70% that becomes waste heat to take care of at least part of your customers' cooling needs.
Unfortunately, the capital costs for these systems are immense, and mostly due to all the piping you need to lay. As a result, the technology only took off in Communist or mildly Socialist countries whose central planning did what finicky venture capitalists wouldn't. Another hurtle, besides the cost of the actual piping, is the amount of infrastructure a new net would need to plan around. This is undoubtedly the biggest hurtle for the locations which would benefit most from this technology (that is, places with high demand per unit area). Current labor costs and supplies are no small issue either.
However, there is one niche market for waste heat which has the potential for a great deal of expansion in the United States: biofuels. Most forms of ethanol and biodiesel plants consume large amounts of heat. A frequent feature in proposed ethanol plants is the siphoning of steam or hot waste water from a thermal power plant to cover some or all of the heat consumption of the plant. This can be problematic, since there are no simple correlations between the time of year, the power output, and the heat demand, as there are with district heating. As a result, some hybrid ethanol-power plants are proposed in which the power plant's electricity would be a salable by-product.
-b.
The sign of a trend (upward or downward) matters. However, so does the MAGNITUDE of the trend, and the magnitude of temperature increase has gone up over the past few decades.
While the trend, and the magnitude do matter, so does cyclicalness. There is evidence that climate changes are cyclical, and rapid, and due. I'm not saying that we humans are not changing the climate. I'm just saying that climate change is not all our fault. Like the proverbial straw that broke the camel's back. Sure, the straw is to blame, but so is the rest of the junk that was loaded on the camel.
When our name is on the back of your car, we're behind you all the way!
If the temperature of your cooling medium is 50 fahrenheit (280 Kelvin)
Your process can never be more than 47% efficient. No amount of engineering can change this fact.
Now if the temperature of your cooling medium rises to 90 fahrenheit, then you are stuck below 42%.
Thermodynamics not only says that the ratio must be below 1, it also says exactly by how much it must be below 1.
Comment removed based on user account deletion
Correlation is what would get that person into a squad car and on ice
Causation would be
1 fingerprints of the man on the bullets in the gun (or on the gun in a valid manner)
2 GSR testing showing that he recently fired a gun
3 Blood or hair from him being found at the scene
the CSI evidence trinity Victim -Weapon - Suspect (you have to have a victim a weapon and a suspect all linked)
Any person using FTFY or editing my postings agrees to a US$50.00 charge
Eliminate nuclear and coal power in favor of solar and wind power, and replace the stupid cars with bikes.
Can we assume you've already done this on a personal level? And have ventured out of mommy's basement?
"Before air conditioning, yankees stayed in yankeeland. After air conditioning they moved to places where they weren't welcome."
Actually, refrigeration technology took off in the South before the North. The Yankees you so deride didn't need large plants to manufacture ice for their iceboxes, they had the Great Lakes.
As for electricity generation, you'll note that the New Deal and the Tennessee Valley Authority (TVA in TFA) was interested in improving electricity generation in the South long before consumer air conditioning was available, let alone viable. Southerners were interested in those new-fangled electric lights Northerners were beginning to take for granted.
"We used clothes lines to hang and dry our clothes, not electric driers."
Another technology that caught on in the South more than the North. It's not the North that has to deal with trying to dry clothes in 157% humidity, at least not year-round.
What's purple and commutes? An Abelian grape.
Take it easy and download OpenOffice.
Seastead this.
They surely need a more efficient method for disposing of waste heat. The more efficient one would have "no waste" heat to dispose of.. but life is not perfect.
A nuclear reaction can produce much higher temperatures than that. Finding a good medium, and a good way to contain/control the reaction is an engineering problem.
Uhm, no, it does not. The equation you are referring to is an engineering one. It applies to a single round heat/work conversion. As the "spent" medium is hotter than fresh (and it always is), its heat could be used again in another cycle. And so on (assuming "endless" supply of fresh medium, which river provides), until the difference in temperatures make another cycle impractical. This is how efficiency can — in theory — be brought all the way up to 1 but not quite.
I don't think, the existing plants do even one more cycle because of all the engineering problems involved. Some use the "spent" hot water to heat up nearby buildings and/or orchards... Making these uses (of heat) more efficient is another problem — a lot of the heat-derived electricity is converted back to heat by, uhm, electric heaters, as well as grills and other cooking machinery. But that's a subject for another flame-war...
In Soviet Washington the swamp drains you.
Maybe a better way to say what you meant would be:
"A BWR is designed to contain more excess reactivity than an equivalent PWR, because it must compensate for the negative void coefficient. This excess reactivity makes a BWR less susceptible to xenon precluded startups."
You could achieve the same thing in a PWR by simply loading more fuel or using more enriched fuel. The downside is that you require more control rods to compensate for the excess reactivity.
I have supported the restarting of Browns Ferry Unit 1 for a long time. Because despite the issues nuclear power is an immediatly available and fairly clean power source. Browns Ferry Unit 1 has had a bumpy road to travel since it was commissioned, and then shut down, and then restarted. Since its restart it has contributed clean energy at a time when the Tennessee Valley has been hammered by record high temperatures.record rainfall deficits that have severely curtailed hydroelectric production and made for conditions calling for record power demand levels.
One occurance that also recently occured at Browns Ferry was the automatic shutdown of the reactor due to a coolant leak. TVA reported to the NRC that an unknown amount of reactor cooling water had indeed leaked and they spent last weekend repairing it. After restart the high water temps forced this shutdown. In fact this is nothing new though. We had the Sequoyah reactor using its cooling towers last year due to elevated water temps.
But yeah its been hot for sure. Also of interest is it looks like we are going to get the newest reactor in the US and that it be at Watts Bar. Unit 1 has been online there since 1996, and produces enough juice for 250,000 homes. Unit 2 at Watts Bar was roughly 80% complete when construction stopped. TVA is currently and exploring finishing the construction of Unit 2 giving us yet another clean power source. In September 2000 Watts Bar Unit 1 set a record for continuous operation of TVA reactors of similar design.
It's renewable in some sense, but not others. More specfically, big hydro genereally ends up not being sustainable:
fish spawning, methane, changes to the microclimate. On the other hand, we've not done enough with run-of-river.
Were that I say, pancakes?
Sure it can be higher than 47%. Just conveniently neglect to mention where you're using the HHV and the LHV...
"The South never had a "carbon footprint" before yankee glutons moved to Miami and Atlanta."
It sure burned the heck out of wood, Bo! The spelling is "Yankee gluttons", BTW.
"Most of us grew up without air conditioning and were happy that way. We used clothes lines to hang and dry our clothes, not electric driers. Life was good."
HAHAHAHA! When I see local folks volunteering to go back to an AC-free life I'll buy the connection between "no AC" and "happiness".
I still use clothes lines to dry clothes (clothes smell fresher besides the energy savings), but there is good reason AC is popular among non-Yankees. I don't see any nostalgia for doing washing in wooden tubs and ironing it with (aptly named) "sad irons" either. The tubs are planters and the irons are doorstops, the shotgun shacks whose layout helped somewhat with cooling are empty, and (most) of the people don't look the the folks in a James Agee book.
I'm a "Damn Yankee" (the ones that came and stayed) myself, though I'm far more genuinely countrified (and right wing) than most locals.
If you wanted to keep out the sort of Yankees that wouldn't fit, not selling them everything at fire-sale prices would have done it. The Southeast got rich and is getting richer by urban and suburban sprawl, so if ya want things the way they used to be, move into the Deep South and away from the coast.
"This post is an artistic work of fiction and falsehood. Only a fool would take anything posted here as fact."
Carnot's efficiency itself quickly approaches 1 as the core's temperature rises to thousands, while the river's water remains at under 25C. And none of the existing reactors are anywhere above 50% anyway.
Uhm, can you share the formulas? Carnot's limit applies to closed systems only, which a plant is not (because the infinite source of cold is external).
In Soviet Washington the swamp drains you.
I heard on the radio a couple days ago that they're building an ethanol plant to use the waste head of the local coal power plant.
My first thought was 'great'. I love hearing about waste reduction. When what was previously waste to be disposed of becomes a valuable resource.
I don't read AC A human right
I am just glad, your name is not even available — because all you know is shit.
In Soviet Washington the swamp drains you.
Every subsequent round is less efficient than the previous round, because the difference between the fluids keeps dropping every round. Every round captures a smaller fraction of a shrinking temperature difference.
Not to mention that you are neglecting the energy needed to move all these fluids through your infinite number of rounds.
I'm confused. Why are they throwing away large amounts of hot water at all, if they generate power with steam turbines? Wouldn't it make more sense to keep the hot water and reheat it, instead of heating cooler river water? Or am I missing something? It seems like a hotter river would make them more efficient, since it would take less energy to boil it.
Disclaimer: Evolution comes with NO WARRANTY, except for the IMPLIED WARRANTY of FITNESS FOR A PARTICULAR PURPOSE.
fish spawning, methane and changes to the micro climate don't effect the dam's ability to generate electricity, so it is still renewable energy.
Renewable != earth loving hippy compatible.
What if Tetris was invented by Nazis?
Yes, of course. But it does not explain your assertion, that the total efficiency of this converges to Carnot's. In fact, I don't think, Carnot's limit should even be used here because, once again, it applies only to closed systems. Does not it?
In Soviet Washington the swamp drains you.
What the hell ..
from the story
TVA gets about 60 percent of its electricity from coal-fired power plants, 30 percent from nuclear plants and 10 percent from its 29 hydroelectric dams. Renewable energy sources such as wind and solar account for less than 1 percent.
my question is ?
When did hydroelectric become a non-renewable source ??
What's purple and commutes? An Abelian grape.
Your open-cycle system will never be more efficient than a carnot cycle at the same temperatures.
How about something like a gas absorption refrigerator?
From the article, "The absorption refrigerator is a refrigerator that utilizes a heat source to provide the energy needed to drive the cooling system rather than being dependent on electricity to run a compressor."
Sounds like just the thing for that excess wasted heat...
Yes, it can. However, that is not really germane to his point. He's just giving some examples of fundamental efficiency limits. It doesn't really matter how hot the nuclear reaction really is, it's going to face off against a fundamental limit somewhere. You hit later on another point that does matter, but I don't know that it's good enough.
Thermodynamics not only says that the ratio must be below 1, it also says exactly by how much it must be below 1.Uhm, no, it does not. The equation you are referring to is an engineering one.
It does when given some further information -- such as the fact that the only "free" cooling medium available is at the river's temperature. It is only an engineering equation inasmuch as all fundamental scientific principles are.
I think what you're suggesting is an infinite series of sources and sinks, with infinitesimal temperature differentials, allowing the reaction to take place reversibly (efficiency = 1). The problem, then, is maintaining such an infinite series, or even a small finite series, of temperature differentials, without using up the energy you're saving to do so. And you can't. That violates Carnot's theorem. If you're operating a heat engine between two reservoirs, you can't do better than a Carnot engine. If you manage to set up such a scaling system in the first place, you might get the illusion of greater efficiency, but the fact is that without energy input maintaining the multiple steps at their different temperatures, you're ultimately wasting that temperature differential 100% while you get a short-term illusory "100% efficiency" in your nuclear reaction. The whole system will be as inefficient as ever. And the inefficiencies of a system maintained by energy input should be obvious.
The only sort of way to engineer this without wasting our own energy and adding complexity to no purpose, would be if there is an area that naturally maintains a temperature differential. Maybe some hot springs near a cool river. But when you take advantage of that system, you are in reality using a combination nuclear/geothermal reactor (or nuclear/solar, or coal/geothermal, or whatever), and the overall efficiency is again below the limit overall.
Because I screwed up too. I originally was going to say that the infinite series converged on the Carnot limit. Then I got sidetracked with all the other problems. So it's even bleaker than I suggest. After all, the heat has to go somewhere, and that somewhere heats up...
I'm afraid Wonko's right. The total efficiency converges to Carnot's. If there is any *usable* waste heat left at the end of a cycle to put into another heat engine, then the first cycle wasn't running at full (reversible) Carnot efficiency.
BTW, if a heat engine were ever to be used in a closed system, then its efficiency would quickly converge to 0%, since the hot source would cool down and the cold source would heat up! The Carnot cycle, as I said in my other post, assumes infinite, constant temperature hot and cold sources, i.e. effectively the same as a system where heat is constantly added to the hot source (by a nuclear reactor) and taken away from the cold source (by a running river) to maintain a constant temperature.
What's purple and commutes? An Abelian grape.
A little noted fact of the cold war is that a very large amount of the US total electrical generation capacity is in the TVA region (Tennessee River - Dependent) The loss of this reactor is serious as the whole USA has no reserve capacity at peak load and with the heat wave over the East USA this is a critical loss. If it were the only reactor in danger this might be of no concern. The US TVA operates 5 big reactors and numerous coal fired plants all of which have the Tennessee River at thermal capacity to cool them and the river is dropping daily.
If heavy sustained rain does not fall on the Tennessee River Valley over the next 3 to 4 months an event which is historically unlikely, the loss of something close to 15 times the Browns Ferry reactor in capacity is likely to hit the USA. There is nothing to pick up the load. The loss of this one reactor is nearly equal to all the wind energy the USA generates. This loss threatens the operations of every one of the 48 US States. With the possible loses in Alabama Power pools and their reactors etc as well as Georgia Power, this poses the very real risk of cutting the energy supply of the USA by a very large fraction. As I write the North Alabama region is short 60 inches of rain over the past 18 months. The US TVA has been drawing down storage for 5 years now. There is no reserve and little prospect of one for some years to come.
I had warning of this imminent event when the City of Huntsville requested from TVA more water for its treatment plant and was turned down for supply. I knew then that the supply was gone.
Never Politically Correct ~ I prefer the facts If you don't like what I say, get a life, or comment yourself.
Yes. Both are minor points, however, because the core of a reactor can be much hotter than 1000C — it is only our present engineering limitations, that cause us to keep lower.
Yes, indeed. Well, back to the T_c/T_h ratio then. The ratio could be 10% and lower — there is nothing "fundamentally" impossible about that. And it means theoretical efficiency of above 90%...
Exactly! This was my point before I got dragged into discussing that maximum itself. If the "spent" water is hot, the plant must be not be working at the maximum theoretical efficiency (whatever it is). Pushing it closer to that limit is an engineering problem — whether it can be solved by deploying multiple heat engines or somehow else is not relevant.In Soviet Washington the swamp drains you.
Dams silt up.
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"We used clothes lines to hang and dry our clothes, not electric driers." We still do use a clothes line, in the summer. In the winter, well, at 28 degrees F and a freezing fog, the usual December conditions here, your clothes will not be getting dry outdoors.
Take it easy and download OpenOffice.
If you have a google mail account you could send the slide to yourself and then view it with Google's online PowerPoint converter.
Jumpstart the tartan drive.
Mi - Wonko and SMNW are both right and know their Carnot cycle, thermodynamics, etc.
If you want to continue to beat this dead horse, I think your best bet would be to educate yourself about thermodynamics, the Carnot cycle, and what it means to have inifinite temperature reservoirs.
Just as real world efficiencies can only approach the Carnot cycle, your answers can only approach the previous postings as you learn more about what you are talking about.
Wow, my brain isn't functioning today.
"Ladies and gentlemen, my killbot features Lotus Notes and a machine gun. It is the finest available."
I pointed out that it is not particularly renewable in the generally assumed, broader sustainable sense.
Were that I say, pancakes?
I can see you read my post, but I don't think you took it all in, did you stop reading after the first paragraph perhaps?
At what point did I even suggest that climate change is not occurring, that it is not caused by our actions, that we should not take action now? I stated that we should go with the evidence we have (and take action immediately to reduce emissions that impact on our climate) but not stop looking for other potential factors or for that matter additional factors. I would hate to find that we have missed something important because we wouldn't allow people to follow their own theories through.
Yes climate change is occurring, yes it is our own fault, yes we need to do something about it, what we don't need to do is go off half cocked when people suggest that we need to continue to investigate the issue at the same time as dealing with what we already know.
As for the murder analogy, I found it amazing that someone would actually suggest that if there is enough circumstantial evidence that someone killed someone else there is no reason to actually gather hard evidence, or to simply make that leap that confirms the facts.
Uhm, that was just an example: if there is "waste heat", it should be re-used.
We now seem to have established, that a plant running at or close to the theoretical maximum (Carnot's) will not, in fact, have "waste heat" to speak of.
That the current plants don't are — as I originally stated — an engineering problem.
In Soviet Washington the swamp drains you.
Ben Hocking
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The important point is that it would work here. Well, for certain definitions of "here". Denmark and New York both have cold climates. I'm not sure how practical this would be in the South.
Ben Hocking
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Ben Hocking
Need a professional organizer?
"freezing fog"
157% humidity is 157% humidity. It may take far less grains of water to saturate a pound of air at lower temperatures (which is why it feels so dry when you step into a heated building), but saturation is saturation.
I live the same area, and even gone to guntersville as a weekend get away (American Idol winner, Taylor Hicks just bought a house on the river), if the river gets too hot, just the heat energy!
I hope the levels dont go down too far, as alot of shipping is done on the river and that would create more heat as things would need to be moved by truck instead!
it is sustainable, because it can be sustained, that's what sustainable means. It may fuck up the environment, but sustainable does not mean it is environmentally friendly, it means it will not run out. If the sun spat out pieces of coal that fell onto the earth like rain, then burning coal would be sustainable, it would still be bad for the environment, but it would be still sustainable. Rewnewable, means that the resource is renewed, in this case hte resourse is water which is higher than sea level, and it is renewed, even if I kill a thousand tigers, destroy a dozen farms and poison a hundred babies collecting that water to generate power, more water will fall, renewing the water I used. Hence Renewable.
You need to stop munching your muesli and take a remedial reading class yourself.
What if Tetris was invented by Nazis?
Because they decided that using a once-through cooling cycle was cheaper, rather than worrying about the 0.1% of the time where they wouldn't be able to run the plant. It's really not a big deal.
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
Hmmm - you don't live in TVA's service area do you. We are in the midst of a very severe drought. Lakes are way below normal levels. Therefore TVA can't generate hydro electricity without literally running out of water. The lakes are used by virtually every city in the Tennessee Valley for a water supply and you have to meter water out to the rivers in order to prevent an ecological disaster - think fish, trees, acquatic mammals, etc. Proper management of the water supply dictates that hydro generation has been very sparingly used all this year.
It's not that amazing. Remember, we also figured out centuries ago that the earth is millions/billions of years old, but even now people still don't get it. They think the earth is 6000 years old, despite plenty of evidence and artifacts from human cultures older than that, let alone geological and paleontological evidence.
L. Ron Hubbard was a genius, creating an utterly ridiculous "religion" and then getting people to believe it by the millions, and spend their fortunes on it. It illustrates that there's no limit to the insanity that you can make people believe.
Warning: this article may contain humor, sarcasm, parody, and perhaps even irony. Read at your own risk.
The reactor was shut down because the water exiting the plant's cooling system exceeded an average of 90 degrees F over a 24 hour period. The plants have an agreement with the state to limit the temperature of the water they put into the river. The water in the river is not even remotely 90 degrees F.
Brown's Ferry also just recently started one of its reactors after a long downtime, so this only kicked us back a few months. It's not a big impact to the nation's grid, not even to the local area.
As for why we don't recapture the energy in the heated water to make even more power, well, they just didn't think it was necessary back when we used to build power plants back in the 60's. Investing money in anything nuclear in the US is political suicide.
"TVA gets about 60 percent of its electricity from coal-fired power plants, 30 percent from nuclear plants and 10 percent from its 29 hydroelectric dams. Renewable energy sources such as wind and solar account for less than 1 percent."
That was their choice. Now it's clear that wasn't such a good choice.
TVA is one leg of the old dinosaur. Sounds like gangrene is setting in.
"You must try to forget all you have learned. You must begin to dream." -- Sherwood Anderson
The balance here is that a BWR doing a startup has little to no voids (steam replacing water), so many more neutrons are available for fission. Unless the reactor is in "coastdown" where U-235 (and other fissile material) is in limited supply, the effect of more neutrons available to the fissile material exceeds the poisoning effect of additional Xe-135.
So what can you do with a BWR that does not Boil?
Friends don't help friends install M$ junk.
Fish spawning certainly does effect the dam's ability to generate electricity. Water diverted to fish ladders is water that doesn't go through the turbines for example. Depending on the fish species and river conditions sometimes dam operators have to sometimes either withold or increase water going downstream to control conditions downstream.
Global warming at work folks.
climatology models predicted first rises in heat waves, then increased frequency of droughts and storm severity.
Predictions for the long term include the distinct possibility the south and great plains become arid enough to challenge farmers and possibly become desert (and canada's central region becomes warm enough to become the new world's bread basket).
the poetic thing about this is most of the people living in these regions are the ones using the most polluting of vehicles and voting for people who gut environmental protection laws. I'm agnostic, but it makes you wonder sometimes : )
VLC FOR MAC IS DYING! IF YOU DEVELOP, PLEASE SAVE IT!!
Ironically enough, I drive a big environmentally-unfriendly 3/4 ton diesel pickup, and what do I do with it? I go repair wind turbines.
Jesus is coming -- look busy!
I ride year round in Chicago, and it's not all that bad. You need to spend about $50 on gear to keep you warm to -10F, but you'd need that anyways unless you've got a car with remote start.
In other words, it's renewable, but we have to say it's not for some mysterious reason. Keep in mind solar and wind also have "nonrenewable" problems that look suspiciously like the list you just named.
I guess as an idiot AC you'll never return, but:
"rain there is *not* "historically unlikely"
Is just what he said! Idiot.
If Google really cared they would fix Android Chrome to reflow text, instead of discriminating
Correlation does not imply causation.
Actually, it does. The fallacy is to assume causation because of the correlation.
One heat-to-mechanical cycle is limited by the Carnot cycle, but the waste heat can still be used for other purposes even driving other heat-to-mechanical cycles working at lower tempertaures. Of course if you placed the reactor at the coast you could use the waste heat to do things like desalination.
Engineering is the art of compromise.
Where they bet on whether or not we have one?
tm
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Using this to impeach nukes is profoundly wrong.
I'm in favor of alternative, renewable energy sources, but each source has varying degrees to which it is useful in particular situations for technology and production cost reasons. (For example, many places just don't make a good wind farm - and some places make an extremely mediocre and very expensive one.) I think we're going to have a bloom of much better solar at some point, but there's definitely still some room for improvement there.
I'm also certainly not supporting the current federal administration's energy policy, and I certainly do agree that a greater mix of power would be better.
However - despite repeatedly building coal fired plants that release literal tons of radioactive (definitively cancer causing) uranium into our air to be sucked up into our lungs - we're so afraid of anything called nuclear that to my knowledge we haven't issued a license to create a new nuclear plant in many years. I think we should wipe that kind of pollution from the map with large and increasing taxes that are specifically based on the pollution released. The only way we're going to do that in the short term would be to use more nuclear, not less, in combination with many other technologies.
So a lack of capacity is certainly not nuclear technology's fault. A reasonable answer to the GPs fears would be to have nuclear capacity spread out a little more so it wasn't so easily susceptible to drought, ANOTHER reasonable defense would be to have simply more average capacity, and a third defense would be to make plants which are more efficient - which would undoubtedly happen if we compared one we might build now to one decades old. Just look at the efficiency of cars from a similarly long time ago.
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How about .. all the good sites have dams on them so there's no point talking about it either way? It's not like anyone can expand hydro power generation on any kind of scale.
...to put not too fine a point on it.
Suburbia is a huge aggravating factor in our energy problems, whereas urban environments with avg building height of 4 or more stories are far more efficient. They suddenly enable walking, biking, convenient bus and lightrail networks. Heating and cooling become more efficient just from building configuration.
But since the White Flight in the 1950s, most Americans have hated urbanity. I think many are going to have to change their minds.
Actually, you still have pumped storage into underground reservoirs. Great way to store power from other sources. But yes, expanding hydro isn't going to be practical for a lot of the world. But still it seems unfair to ignore hydro in a listing of renewable energy sources even if the TVA can't expand their use of it.