Talk:Fossil fuel power plant

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Information from Fossil fuel power plant (or a previous version of it) is being actively used in the pool of 'Did you know?' facts on the Energy Portal.

If you want to help, we could use some appropriate photos. There is plenty of opportunity for expansion. There could be a section on operator controls, and more detail on water treatment, and pollution control, for example. --Blainster 10:00, 2 Mar 2005 (UTC)

This is written from memory (personal experience) so checks on things like flow rates, pressures, and temperatures are particularly appreciated. --Blainster 00:00, 9 Mar 2005 (UTC)

[edit] Water purity

It seems the industry standard unit is microsiemens per centimeter. A Google search turned up this reference [[1]] whose Table 1 says chemically pure water has a conductivity of 0.038 microsiemens per cm, and demineralized water up to 1.0 microsiemens per cm - which looks like the magnitude for boiler feedwater. Per metre would be 100 times smaller, which isn't possible. --Wtshymanski 19:22, 5 August 2005 (UTC)

indeed, a conductivity of 0.038 uS/cm is ultrapure water, also known as MilliQ water. This quality is quite hard to achieve, requiring expensive columns etc. Still I don't understand the question your asking... Sikkema 12:52, 23 January 2007 (UTC)

[edit] Comparative Stack Gas volumes

This section compares flue gas volumes for different fuels, but does not state why this is of interest. An encylopedia needs to give context for the information presented, so that it will be useful to non-specialists. Much of the data in the table is not relevant to its accompanying statement. The image itself is problematic, consisting of a bright color graphic of a table of data. The color is obtrusive. The format is wasteful of page space. As an image, the table is uneditable. I suggest editor Mbeychok replace it with a table that is editable. As it stands, the graphic is not any more useful or relevant than putting steam tables or power generation curves into the article. --Blainster 21:24, 20 January 2006 (UTC)

So what is it, a rough measure of how 'smoky' each fuel is? Tom Harrison ^Talk

Actually, no, "smokiness" generally refers to opacity, or how difficult it is to see through. Opacity is measured in percent, and is a rough measure of the concentration and size of particulate matter in the flue gas. I am waiting for editor Mbeychok to explain what he has in mind. --Blainster 23:04, 20 January 2006 (UTC)

(Response to Blainster from MBeychok) The concerns of the public and of our regulatory agencies with what comes out of the flue gas stacks from power plants (or any other large combustion furnaces) has increased ten-fold or more during the twenty years since you worked in a power plant. A great many people have the mistaken idea that coal burning creates a great deal more total flue gas than a "cleaner" fuel like natural gas. As shown in my table, coal burning does create more flue gas, but only marginally so. I did not want to dwell on that in my contribution lest I sound biased in favor of coal burning ... which I am not. I wanted the table to show the facts and to speak for itself.

I suggest the information in the table needs better verbal explanation. The section does not state why the table belongs in a general article describing a power plant. Remember the encyclopedia is targeted at the educated layperson, so you need to provide context. I don't see how explaining the importance of flue gas volume could be considered a bias. --Blainster 22:56, 26 January 2006 (UTC)

Deleting the table and only leaving the comparative scf/10⁶ of flue gas for each of the fuels pretty well "guts" my contribution because:

The credibility of my calculated results depends upon readers being able to see the compositions that I used for each fuel and to ascertain that they are typical ... not selected to bias the results. With those compositions, readers could actually perform their own calculations to check my results if they wanted to do so. Without the compositions, they could could not make independent checks.
The credibility of my results also depends upon the readers being able to see what percentage of excess combustion air I used ... again to ascertain that I did indeed use typical values. And those excess combustion air values are also needed to permit independent checks of my results.
- I was attempting to condense the information to summarize the point I think you were trying to make. But of course your followup edits and thoughts are appreciated. This kind of detail is more likely to confuse than enlighten the general reader. If you wish to provide a tutorial, Wikibooks would be a more appropriate forum. There would also be more latitude for calculations in a subarticle on air pollution measurement and control. --Blainster 22:56, 26 January 2006 (UTC)

Quite a bit of my table concerns how to convert the results into units used by some 99% of the world (the USA is the only nation still using scf and Btu's rather than metric units). Believe it or not, the vast majority of people on the planet don't know how many inches there are in a foot.
- Unit conversions are normally covered by links to articles on the units which already exist in Wikipedia. There are already some examples of this in the article. --Blainster 22:56, 26 January 2006 (UTC)

All steam tables contain the same data because water has a fixed set of physical and thermodynamic properties. There are literally thousands of different composition natural gases, fuel oils and coals, all with different heating values, carbon-to-hydrogen ratios, and different physical properties. That is another reason why the readers should have my table to look at rather than just the final results.
- There could be loads of detail on steam properties which drive pressure vessel design, or coal properties which drive furnace design, but these things really belong in subsidiary articles. --Blainster 22:56, 26 January 2006 (UTC)

As for my table being a graphic image that is not editable, I would point out that photographs are also not editable. I don't see where that is relevant. I created that image some time ago so that I could use it on a number of Internet forums without having to cope with the plethora of markup languages in use (HTML, BB code, PHP code, Wiki markup, etc).

Placing textual information into an image is not allowed by the community, because it prevents collaboration, which is the heart of the Wiki process. I can sympathise with not wishing to learn table code in Wiki, but one way to handle that is to place the information on the page and ask for help in getting it formatted. --Blainster 22:56, 26 January 2006 (UTC)

As for your finding the color "obtrusive", one person's "obtrusive" may be another person's "favorite color". Does the Wikipedia have a "color" standard somewhere that I haven't yet found? Or do the Wiki editors have some "color police" looking for inappropriate colors?

This is of course my opinion only. Color is negotiable, I would suggest pale colors are more readable on text pages. --Blainster 22:56, 26 January 2006 (UTC)

Blainster, I also responded to you in your User discussion page ... I hope that you've seen it.

Mbeychok January 20, 2006

Yes, thanks for your input. A brief note on my user page will suffice (that triggers the message flag) with no need to duplicate the detail here. See my responses above, and once again, I appreciate your help in improving the article. --Blainster 22:56, 26 January 2006 (UTC)

[edit] Steam-electric power plants

I removed steam-electric power plant as an alternate name because it is incorrect. The article I created gives a better definition. Also, not all fossil fuel power plants are steam-electric. Gas turbines and reciprocating engines can be fossil fueled and they are not steam-electric (reciprocating engine power plants usually aren't very big, they range from 1 kw to about 20 MW). -- User:Kjkolb 22 January 2006

[edit] Further Response to Blainster

In your original message to me on my user talk page, you said:

"We do not own the material we contribute, so be prepared to have your entries edited mercilessly— the thought "but it's my article" should never cross your mind."

It seems evident to me that most of your points against the table that I contributed to this article (which you say that you wrote) are because you do indeed consider the article to be your own. Rather than carry this discussion any further, I have completely removed the table that I contributed. I have better things to with my time. mbeychok 17:28, 27 January 2006 (UTC)

On the contrary, I welcomed the changes you made to my text. It is you who seem to consider your contributions inviolate. It is regrettable that you do not wish to carry on a discussion, which is the heart of the process of building a collaborative encyclopedia. But I harbor no ill will—if you feel inspired to rejoin the endeavor at any time, you are welcome to do so. --Blainster 17:44, 27 January 2006 (UTC)

[edit] Pollution

It seems that a section on pollution should be included but I'm reluctant to do this myself since this isn't really my area. In particular I believe the otherwise generally unknown but potentially very relevant and worrisome aspect of radioactive waste should be included (article currently contains an external link but otherwise no mention of the problem). 212.48.126.140 10:30, 22 May 2006 (UTC)

It is unclear what kind of radioactive waste you are referring to. The small number of radiation sources used in power plant instrumentation are compact, sealed, licensed, and regularly inspected. Fossil fuel plants do not produce any waste of the sort produced by nuclear power plants. All coal has a small degree of natural radioactivity, and this is somewhat concentrated in coal ash, but is a much smaller hazard than the naturally occuring radon gas that collects in residential housing, for example. --Blainster 17:16, 22 May 2006 (UTC)

I was refering to the trace elements that would be insignificant if there wouldn't be such a large amount of coal (or whatever) being burnt. The external link http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html claims that a typical 1GW power station releases 5.2 tons of uranium and 12.8 tons of thorium per year. Even if one considers that maybe only 1% of it is not caught in the coal ash and is released into the biosphere, it still seems somewhat alarming especially considering the public outcry that would result if a nuclear powered facility would release radioactive waste of that magnitude. There are possibly other factors involved that make the situation more harmless than it seems but if there are, it would be good to be able to read about it here. However, I did find this mentioned on the coal page so this is all perhaps a mute point.212.48.126.140 13:15, 23 May 2006 (UTC)

This is true: in a nuclear facility in the UK, called ISIS, the majority of radiation measured outside comes from the precipitation of the radioactive elements from a nearby coal plant. The radiation on the inside is actually lower!!

—The preceding unsigned comment was added by Sikkema (talk • contribs) 12:57, 23 January 2007 (UTC).

I am more concerned about the health effects of mercury release from burning coal than radioactive elements. The EPA was set to implement mercury reduction requirements until the Bush administration pushed it back by ten years. (I think the word you want in the last sentence is moot, meaning debatable, not mute.) --Blainster 18:05, 23 May 2006 (UTC)

What you say about mercury is certainly relevant as well, not to mention whatever other heavy metals there may be, so perhaps a section listing all typical harmful pollutants would be beneficial. I still believe that the release of uranium and thorium is an underrated problem, for example, you wrote previously that radon gas is a concern (being a cause of lung cancer) and it would be interesting to know how much artificially released airborne uranium and thorium contributes to the production of radon (both elements can decay to radon). A hypothesis also exists that airborne uranium can be converted to plutonium, which is well known for its toxicity. (Yes, "moot" is what I meant. :-) Everything in Wikipedia is always so correct, unlike in other forums, one needs to be careful...)212.48.126.140 12:50, 29 May 2006 (UTC)

This article does need a pollution section though. raptor 11:22, 1 November 2006 (UTC)

I agree with raptor and 212.48.126.140, coal is infamous for its health dangers. The section should include radioactive fly ash, soot, nitrogen, carbon emissions, and everything else you can think of, why withhold information if you have it? I'd write it myself, but I don't know enough about it, nor do I have good sources at the moment. Also, to be frank, I don't think anyone cares about any one person's idea of which pollutant is most important; just put all of the pollutants in the section and everyone will be happy. 204.126.2.5 12 December 2006

I have added a very basic section on environmental impacts. Every power generation source on wikipedia has this section; if you feel the need to expand the article to include positive benefits of fossil fuel power, feel free to add those as well. If you take issue with any point of fact, please ask for clarification or citation. But a full discussion of the environmental impacts must be present to clear this glaring ommission of facts and to bring this article up to par with the other energy generation technologies. Sven42 03:28, 21 December 2006 (UTC)

Sven42, I wholeheartedly agree that power plants have environmental impacts ... just as do our autos and almost every other human activity. But your original contribution made it sound as if they were solely "responsible". Even now, your revised contribution includes "air pollution" (which is valid) but goes on to include scare words like "release of uranium and thorium to the atmosphere". Are they not included in "air pollution"? Why do you feel it necessary to use those scare words and why not point out that the amounts are quite small? It is that sort of overstatement that I consider to be a biased POV (point of view). I am an environmentalist myself but there is a difference between stating facts as against expressing what struck me as overblown bias. Regards and Happy Holidays! - mbeychok 05:12, 21 December 2006 (UTC)

I found a reference regarding Uranium and Thorium emsissions, but I'll let it be put in by someone more familiar with Wikipedia's style of writing. Here is the reference, I don't know how helpful it is, but it's at least a start. <http://www.physics.ohio-state.edu/~aubrecht/coalvsnucMarcon.pdf#page=8> —The preceding unsigned comment was added by 66.140.86.116 (talk) 22:07, 29 December 2006 (UTC).

I have read the entire website article that you referenced above. To me, it reads like 20 pages of a vitriolic rant against coal mining and against coal burning. It does not read like a credible scientific paper published in a peer-reviewed journal (or any other reputable journal) would read. For example, here is one quote "Given that so much crud is coming from coalstacks ...". I could find no mention of where this article has been published in any journal or book. As another example, it uses red fonts and very greatly oversized fonts when it wants to hammer home one of the author's points. I invite others to read that article and see if it strikes them as a balanced, credible scientific reference.

I also read the article at [2] which was referenced much earlier in this discussion by 212.48.126.140 ... and it is a much better and more believable article covering the same subject without any ranting. I will therefore include the following statement (paraphrased from the Wikipedia Coal article) in this article:

Coal contains low levels of uranium, thorium, and other naturally-occurring radioactive isotopes whose release into the environment may lead to radioactive contamination. While these substances are present as trace impurities, enough coal is burned that significant amounts of these substances are released, paradoxically resulting in more radioactive waste than nuclear power plants. I will reference that statement as being sourced to the above article provided by 212.48.126.140. I will also include the statement from that reference that a 1000 MW coal-burning power plant could release as much as 5.2 tons/year of uranium and 12.8 tons/year of thorium. - mbeychok 00:30, 30 December 2006 (UTC)

[edit] cold/hot startup

anyone can advise the difference between the 2?

First, let me say that you really should sign your user name to queries or comments. If you don't have a user name yet, you should sign in and get one. :)

That said, I did quite a bit of searching using Google and it appears that:

For thermal power plants, a cold startup is a startup that takes place after the power plant has been shut down for at least 48 to 72 hours (the exact number of hours varies from one reference source to another). A hot startup is a startup that takes place after the power plant has been down less than 2 to 48 hours (again the exact number of hours varies from one source to another). In other words, the difference between a cold startup and a hot startup depends on the number of hours that the plant has been shutdown and the exact number varies from one definer to another definer. The importance of the distinction between the two seems to be related to how long a plant may be permitted to exceed the regulatory limits on the air pollutant emissions of nitrogen oxides for example. In some cases, the nitrogen oxides regulatory limits may be different during hot and cold startups than during normal operation.
For nuclear power plants, the definitions are different. A hot startup is one that takes place while the nuclear reactivity is still decreasing (i.e., the plant has not yet been fully shut down). A cold startup is one where the nuclear reactivity is no longer decreasing because the plant has been fully shut down.

- mbeychok 20:28, 5 July 2006 (UTC)

It also affects how the operator starts up his plant. For example, the boiler will probably have been drained down (to prevent corrosion) prior to a cold start. The operator may need to pre-fire the boiler with gas to warm it, and the turbines be taken off barring (in which they are made to slowly rotate to prevent the hot shaft sagging). The principal effect is however determining how quickly the operator can start up the plant and ramp up its output. BillC 21:48, 5 July 2006 (UTC)

That is right. A large power plant needs to start up slowly to prevent damage to the thick walled metal components by heating them too quickly (thermal stress). This is in contradiction the the way bean-counters would like to run the plant. Jono 58.172.179.32 12:34, 2 October 2007 (UTC)

[edit] Global view tag - re costs

I presume the figures given are for the United States as I doubt that they are the same everywhere. If this is the case, the article should say so. Olborne 21:36, 10 September 2006 (UTC)

Olbourne, do you really think that one sentence about USdollar costs warrants labeling the entire article as lacking a global view? Seems like a pretty drastic personal judgement on your part. Do you have any good references giving significantly different costs in various countries? If so, why not include them in the article? - mbeychok 00:12, 11 September 2006 (UTC)

Olbourne, from what I could find in the History page of this article, it was created on March 2, 2005 by User:Blainster. I suggest that you contact him at User Talk:Blainster about the cost figures. - mbeychok 00:22, 11 September 2006 (UTC)

Olbourne, since you have not responded to my above comments, I am removing the global view tag. - mbeychok 23:17, 13 September 2006 (UTC)

[edit] Trains per day

3–5 trains per day doesn't sound right unless the trains at issue are shorter than unit trains, or are stockpiling fuel. A 2000 MW (sub-bituminous) plant at full load burns about 1000 ton/hour. But this would probably amount to no more than 16,000 tons in a day due to off-peak load reduction. The largest plants of around 3000 MW would then use 24,000 tons, which is still only 2.4 unit trains worth. --Blainster 07:46, 30 November 2006 (UTC)

[edit] Coal power and radiation

I think that the part about coal's supposed radiation exposure should be removed because of the many problems with the referenced article's reasoning. The article was written to promote nuclear power. The author works in nuclear energy and has no experience in dealing with coal or coal power plants. The first problem is that there is an extremely low amount of uranium in coal, about as much as is in the average piece of the Earth's crust. Second, very little of the uranium is released into the air, most of it remains in the ash, yet the article assumes all of it is released. However, even the uranium concentration in fly ash is not very great. It is about the same as the amount found in black shale. Third, whether it is in the ash or released into the air, 99.3% of the uranium is stable U-238, which emits no radiation. Fourth, the little uranium that is released quickly falls to the Earth, giving it little time to be breathed in (U-235 is an alpha particle emitter and can only cause harm if it is breathed in or eaten). Also, there are few people in area immediately surrounding coal power plants around to breath it in. Still, the amount of radiation for any people that are around, like workers at the plant, is minimal.

Besides this, the article makes stunning leaps of illogic and it is embarrassing for it to be used as a Wikipedia reference. One example is when the article claims that coal power is wasteful because of the amount of uranium that it wastes, which could be used for nuclear power generation. However, as I stated before, the amount of uranium in coal is extremely low. This makes the extraction of the uranium incredibly uneconomic. The article uses a number of 1.3 ppm (0.00013%) for the concentration of uranium in coal. The U.S. Energy Information Administration website says that the range of economic uranium ore is 0.05 to 0.20%. Therefore, coal has a uranium concentration about 385 times too low to be considered economic. Even if uranium ores of very low concentrations become economic in the future, it is certain that coal will never be an economical source of uranium. Even the ash, which has a greater concentration of uranium than the coal, is nowhere near economic. There are many other major errors. Several of the most serious occur in the area where the author claims that coal plants threaten nuclear proliferation (when I read through this part I thought that he might be joking because the reasoning is so ridiculous, but apparently he is serious). For all of these reasons, I believe that the content should be removed. -- Kjkolb 21:37, 31 December 2006 (UTC)

I would have no objection to your removing the section I added. I was simply trying to appease the above editors (User:212.48.126.140, User:66.140.86.116 and User:204.126.2.5) who dug up the article and a similar one also. I guess I just went too far in my appeasement. Happy New Year! - mbeychok 06:47, 1 January 2007 (UTC)

Don't worry about it. I'm only disappointed in Oak Ridge National Laboratory (ORNL). You expect information from a U.S. Department of Energy National Laboratory (ORNL in this case) website to be accurate, or at least I do. In almost all cases, I have found their information to be good and in many cases excellent. This article is the only major blunder I have come across. They really dropped the ball when they let this article get published. The United States Geological Survey has more accurate information on the subject.

Nuclear power has many advantages (few emissions, relatively abundant, massive fuel deliveries are unnecessary (they can be a problem for coal plants, especially those far from coal mines)) and many disadvantages (high capital cost, need long term radioactive waste storage, current designs are unsuited for anything but base load operation). However, people have been using the ORNL article to make false claims about coal power while promoting nuclear power (it has been used on other websites and on at least one other Wikipedia article). Making such claims does not do anyone or any cause any good. It makes nuclear power look bad for lying and fear mongering and it makes coal, which provides half the electric power for the U.S., look bad by those who take it at face value (coal has many actual problems of its own, of course). Unfortunately, bashing the other energy sources and making exaggerated claims about your own seems to be common practice in the energy industry and in energy research. It is not limited to coal, nuclear and oil, either. Some of those involved in renewable energy are equally guilty making false claims about themselves and others.

Anyway, I'll remove the content now. Anyone who objects later, please let me know. -- Kjkolb 12:46, 5 January 2007 (UTC)

[edit] Other Pollution Issues

Looking at the image ‘PowerStation3.svg’, it looks as though the cold water used in the condenser (8) which is then cooled inside the cooling tower (1) forms a closed system. Actually power stations tend to be sited by rivers, and in practice I think that it is river water which is used to condense the steam. Once it comes back out the condenser and is cooled by the cooling tower, I think it is then sent back into the river. I say this because I have heard about the damage to the environment that power stations can cause by raising river temperatures. As good as the cooling towers may be, they do not get the water back down to the original temperature of the river water. Which I suppose is the reason why fresh river water is then used again, because it is colder and will be better at condensing the steam. As you may be able to tell, I am no authority on these things, but I did want to make the comment.

I do not really understand why the steam must be condensed at all. It seems like a remarkable waste of energy. At the very least the hot steam could be made to do more work as it condenses – like in early steam engines, the vacuum type. Or a stirling engine could be used. In some places I know the hot water is used for heating. Why though, is the steam not simply fed back into the furnace? From the image ‘PowerStation3.svg’ I can see that after the high pressure turbine (11), the steam is reheated in the reheater (21). Why can we not reheat the steam coming out of the low pressure turbine? Over the years I would like to think that engineers have got quite good at perfecting some of these things. From this article though, I can not find the reason for what appears to simply be spectacular energy wastage (which in turn of course means needless pollution). Could someone please educate me? --JB001 13:16, 4 January 2007 (UTC)

Answering my own question, I suppose the vacuum created by condensing the steam helps drive the turbines faster. Does this sound right?--JB001 14:28, 4 January 2007 (UTC)

JB001, as stated in the article:Typically the cooling water causes the steam to condense at a temperature of about 90–100 °F (32–38 °C) and that creates an absolute pressure in the condenser of about 1.5–2.0 in Hg (5–7 kPa), a vacuum of about 28 in Hg (95 kPa) relative to atmospheric pressure. The steam is condensed at a temperature which results in a very low pressure (94% below atmospheric pressure!). That is done so as to utilize almost all of the usable energy in the steam and and thereby increase the efficiency of the turbines. So your self-answer was almost right.

Simply reheating the very low pressure steam exhausted from the turbines would not raise its pressure and thus it could not be re-used as high-pressure steam. However, the condensed steam is reused as feedwater to the steam generating boilers.

As one other point, not all power plants are located next to a river, lake or ocean. Regards, - mbeychok 17:07, 4 January 2007 (UTC)

Mmm. Thanks. I’m not great at thermodynamics. I’m glad there are engineers out there obviously more competent than I! I knew that absolute profligate waste would have been exorcised from the system by now. I was wondering just how efficient the process actually was, and how it could be improved. In this article there are sections on ‘Supercritical Steam Plants’, and ‘Gas Turbine Combined-Cycle Plants’ which partly address this. There is also an article on Combined Heat and Power elsewhere, that claims that by utilising the heat for productive purposes (heating things you want to heat), rather than just losing it to the environment as normally happens using cooling towers – you can improve efficiency from 35% to 70%. This would also eliminate the heat pollution of rivers some power stations create as I mentioned earlier.--JB001 04:42, 5 January 2007 (UTC)

This article is about conventional power plants burning fossil fuels. The large majority of power plants in the world are conventional plants. Their thermal efficiency is about 35%. If one wants to learn about other types of power plants, then one does exactly what you did ... that is, read the articles devoted to other types of power plants. Combined-cycle plants do indeed have higher efficiencies. And Cogeneration plants also have higher efficiencies.

The problem with Cogeneration is that there must be a nearby large need for heat. Not all power plants are in small European countries with nearby towns needing central district heating (and that for only the winter season).

I can assure you that if there is an economic justification for cogeneration, power plant developers and their engineers will certainly consider it. As for thermal pollution of rivers or other waterways, a good part of the steam condensing can be done with air-cooling rather than water-cooling ... and some power plants do utilize air-cooling. But again, in today's world, there must be an economic justification for doing so. - mbeychok 18:04, 5 January 2007 (UTC)

[edit] Re: 'waste heat' edit...

In the 'Steam Condensing' section, after my edit, here is an extract of what the article used to say:

The heat absorbed by the circulating cooling water in the condenser tubes must also be removed to maintain the ability of the water to cool as it circulates.

My edit has since been reversed by mbeychok, removing my reference to waste heat, who states that it is 'out of context', and that a cooling tower does not "produce" waste heat.

I would like to defend a reference being made to 'waste heat' in this article. In the 'waste heat' article, reference is made to cooling towers, so I do not think that it is out of context. The heat is ‘waste’ because energy has been expended in creating it, and yet no useful application is found for it – and it is simply dumped into the environment through the cooling towers.

It may not be intentional that a cooling tower ‘wastes’ heat, but in keeping the cooling water cool, that is effectively what it has to do. It is as much a product of its operation, as the cool water is.--JB001 02:15, 8 January 2007 (UTC)

JB001, with all due respect, I have no intention of getting into a discussion or debate with you about semantics. The water entering the cooling tower is just barely warm water at a temperature of about 120 °F (49 °C). There is no practical place to use such low level heat in a power plant. As you just admitted in a message on my talk page, you have a "bee in your bonnet" about wasting heat. That was clearly evident in our previous lengthy discussion just above. Having a "bee in your bonnet about not wasting heat" is a good thing ... but it can be carried to extremes. Yes, that heat removal in a cooling tower ends up in the atmosphere. But your edit linking it to an article on waste heat and your wording that the lost heat is "dumped into the environment" makes it sound as if power plants are deliberately doing something that is "wrong" of them. That is what I meant when I said that your edit "was out of context".

There are a lot of valid examples of foolish waste in this world ... just look at all of the unnecessarily large SUVs on the road wasting huge amounts of energy. Expend your efforts on those sorts of waste rather than worrying about the very low level heat rejected by cooling towers. Now, once again with due respect, I have to get back to more important work. - mbeychok 03:35, 8 January 2007 (UTC)

I propose that the article say the following:

The heat absorbed by the circulating cooling water in the condenser tubes must also be removed to maintain the ability of the water to cool as it circulates.

This is done by pumping the warm water from the condenser through either natural draft, forced draft or induced draft cooling towers (as seen in the image to the right) that reduce the temperature of the water, by 20–30 °F (11–17 °C), by evaporation - expelling waste heat to the atmosphere. The circulation flow-rate of the cooling water in a 500 MWe unit is about 225,000 US gallons per minute (14.2 m³/s) at full load.

Hopefully this is more agreeable, and it avoids the same wicked connotations of deliberately producing waste. I think it actually clarifies what is happening, and it is good to have convenient links to other related articles for people who are reading up on the subject.--JB001 09:57, 8 January 2007 (UTC)

That is agreeable with me. Happy New Year! - mbeychok 17:45, 8 January 2007 (UTC)

Jolly good then, 'tis done! Happy New Year to you too! :-) --JB001 09:00, 9 January 2007 (UTC)

[edit] Do we really need 4 articles on the same subject?

Wikipedia now has these 4 articles, all on the same subject:

Do we really need all of these? In my opinion, this sort of thing reflects badly on Wikipedia. What can we do to get these four articles merged?? - mbeychok 17:53, 23 January 2007 (UTC)

[edit] Is this correct?

It is stated that: "Nuclear power plants generally cannot reheat process steam due to safety requirements for isolation from the reactor core. This limits their thermodynamic efficiency to the order of 34–37%."

So far every diagram I have found on the net shows that steam is cooled and re-heated. Examples:

—Preceding unsigned comment added by Vynbos (talk • contribs) 10 February 2007 (UTC)

[edit] Why is the water cooled by the cooling towers?

This question was skirted around in the "Re waste heat" argument above but I didn't think that the reason why the heat could not be recycled. Can anyone clarify this issue, because wouldn't Power Stations be more efficient if the heat was used to warm water going into the system rather than wasted by being emitted by the cooling towers. Even if it was only a small temperature increase, the heat saved would be significant over the lifetime operation of the powerstation and would save having to build a cooling tower. My son asked me this question while doing his school homework and I was hoping this artcle might address his question. I would be interested to hear what you think about this. Wikimsd 15:56, 31 March 2007 (UTC)

The water going out to the cooling towers is warm (50 °C, 120 °F) because it has just picked up heat by condensing the steam (now turned into water) which circulates through the boiler and turbine. Because the cooling water was in close contact with the condensate, it is nearly the same temperature, and thus cannot be used to heat up the condensate. There is no place else it can be reused to increase the thermodynamic efficiency*. The condensate is also about 50 °C (120 °F), as cool as it will get. The condensate is now heated in several stages by what is called "extraction steam" coming from exhaust along several points from the turbines, as it is pumped through the system headed back towards the boiler.

*The small amount of purified "makeup" water coming into the system is already warm in some stations because it has been purified by distillation. Some of the cooling water could be used to slightly warm the makeup water at stations using ion exchange purification, but this amounts to only 20 gal (75 L) or so per minute, a tiny fraction of the total amount flowing through the system, not enough to affect efficiency. --Blainster 18:46, 31 March 2007 (UTC)

To expand on Blainster's response, the amount of recycled, circulating cooling water may be as much as 20-40 times the amount of fresh water makeup needed by the boilers (because almost all of the boiler feedwater is recycled steam condensate). That means that the amount of heat that could be recovered by the small fresh water makeup flow rate would be very, very small. It certainly would not be enough to justify the cost of the heat exchangers that would be needed. Power plants are not public charity foundations ... they must be an economically sustainable operation or go out of business. - mbeychok 19:01, 31 March 2007 (UTC)

[edit] Style/correctness

There are some issues with style and correctness that need to be addressed in this article. It could use and overall audit, but just to call out two things that I noticed:

1) style - in the "Steam Turbine Generator" section, third paragraph, the statement "...no permanent magnets here." seems unprofessional to me.

2) correctness - in the "Steam Condensing" section, the temperature conversions are clearly wrong. In the third paragraph it lists the range as 11-17C with 20-30F in parentheses. But even a quck calculation shows this is wrong: 11C*(9/5)+32=51.8F, not 20F. This also assumes that 11-17C is correct, which I suspect the range may be a little higher if you consider ambient conditions of the location of some power plants, such as Nevada.

Perhaps this article could benefit from having some cleanup tags (http://en.wikipedia.org/wiki/Wikipedia:Template_messages/Cleanup) attached. Tkemp 14:57, 9 April 2007 (UTC)

Re: your item 2– the temperatures you are referring to are temperature differences, not temperatures, so they are correct. --Blainster 10:39, 19 May 2007 (UTC)

[edit] Environmental impacts section

I removed the request tag for references substantiating global warming/climate change effects. The debates are ongoing, and there is no shortage of adequate references for various positions presented in the linked articles from this section. This article appropriately mentions the environmental issues that power plants must address, but I wouldn't want to see this section devolve into dueling references to those issues. Perhaps the section could be modified to emphasize which items are consensus issues and which ones are still being deliberated. --Blainster 10:39, 19 May 2007 (UTC)

Blainster, I agree wholeheartedly that it would be well to modify the "Environmental impacts" section to emphsize which items are completely consensus items and which are not. For example, read this article in the Wall Street Journal by Richard Lindzen (Alfred Sloane Professor of Atmospheric Science at the Massachussetts Institute of Technology, one of the world's most prestigious scientific universities) in which he most strongly disagrees with the scientific underpinnings of the so-called global warming. Other dissenters with the scientific underpinnings of the global warming theories are:

Patrick Michaels, University of Virginia. Past President of the American Association of State Climatologists and former program Chair for the Committee on Applied Climatology for the American Meteorological Society. Contributing Author and Reviewer of U.N. Intergovernmental Panel on Climate Change (IPCC).

John Christy, Professor of Atmospheric Science and Director of the Earth System Science Center, University of Alabama, in Huntsville. Alabama State Climatologist. NASA Medal for Exceptional Scientific Achievement and American Meteorological Society Special Award. Fellow in the American Meteorological Society.

Henk Tennekes, former research director of the Royal Dutch Meteorological Society.

Aksel Winn-Nielsen, former director of the U.N.'s World Meteorological Organization.

Dick Morgan, Researcher in Climatology, University of Exeter, United Kingdom and former Advisor to the World Meteorological Organization.

Dr. Oliver W. Frauenfeld, Research Scientist at the Cooperative Institute for Research in Environmental Sciences Division of Cryospheric and Polar Processes, University of Colorado. Contributing Author to the IPCC Working Group 1 Fourth Assessment Report.

Roy Spencer, Principal Research Scientist, University of Alabama Huntsville. Former Senior Scientist for Climate Studies at NASA’s Marshall Space Flight Center. Recipient of NASA's Medal for Exceptional Scientific Achievement, American Meteorological Society's Special Award.

Robert Davis, Associate Professor of Climatology, University of Virginia. Member of EPA Global Change Research Strategy, and the NOAA Data Management Advisory Panel. Contributed to the 1995 Report of the IPCC. Past Chair of the American Metrological Society’s Committee on Biometeorology and Aermeteorology.

Robert Balling, Jr. Professor, Department of Geography and former Director of the Office of Climatology, Arizona State University. Climate Consultant to the United Nations Environment Program, The World Climate Program, World Metrological Organization, UNESCO, and the IPCC.

William M. Grey, Colorado State University Emeritus Professor of Atmospheric Science at Colorado State University, and head of the Tropical Meteorology Project at Colorado State Universities’ Department of Atmospheric Sciences.

Boris Winterhalter, Professor of Marine Geology, University of Helsinki, and former Marine Researcher at the Geological Survey of Finland.

Igor Polyakov, Professor at the Institute of Marine Science, University of Alaska.

Blainster, I am too pre-occupied with some serious health problems to undertake any re-write of the "Environmental impacts" section. I urge you to undertake the re-write that you suggested. It is needed and it would be a meritorious service to do that re-write. - mbeychok 19:34, 19 May 2007 (UTC)

[edit] The "Diagram of a steam power plant boiler" is incomprehensible.

The subject diagram (the third image in the article) is practically incomprehensible and completely lacks any labeling of the major component parts of a power plant boiler. Can anyone find an easier drawing to understand? One that shows and labels the radiant section tubing, the convection section superheater tubing and the convection section economizer tubing ... as well as the steam drum. I have tried and failed to find such a drawing. - mbeychok 20:40, 28 May 2007 (UTC)

[edit] Why fossil fuel power plant needs cleanup

See above discussion for a fuller explination. The article just seems a little too dirty, given the nature of the power produced.Jbntj 02:05, 5 August 2007 (UTC)

I am not trying to be difficult. But I simply don't know what you mean by "dirty". Do you mean the content is incorrect? Or the style and formatting doesn't meet Wikipedia standards? Or what? Please explain a little better and give a few examples perhaps? Regards, - mbeychok 02:25, 5 August 2007 (UTC)

[edit] Expansion required

Hi everyone, as per discussions with Mbeychok on wikiproject Environment I would suggest that this article would benefit from mention of "clean coal" technologies. There are numerous plans for CO2 sequestration from fossil fuel power plants. There is no reason technically these plants are not viable and it looks like we should have facilities under construction in the not so distant future. --Alex 12:23, 6 August 2007 (UTC)

[edit] Supercritical steam plants

The statement "Nuclear power plants generally cannot reheat process steam due to safety requirements for isolation from the reactor core. This limits their thermodynamic efficiency to the order of 34–37%." is not true. Nearly all nuclear power plants have reheating. They use extraction steam from the high pressure turbine and line steam from the steam generators (PWR) / reactor (BWR) to reheat the exhaust of the high pressure turbine. The lower efficiency is due to the lower initial conditions, and that's it.15.243.169.72 18:02, 20 August 2007 (UTC)

[edit] The "Diagram of a steam power plant boiler" image is incomprehensible and should be deleted

The "Diagram of a steam power plant boiler" image in the "Boiler operation" section ( [[Image:Turmkessel02.png]] ) is a densely detailed construction drawing of some kind and it is completely incomprehensible because it does not label the various sections and equipment items. It should be deleted until someone adds labeling of the various sections and equipment items. Perhaps those sections and equipment items could at least be numbered and then a list be added to the drawing naming each of the numbered items.

If there are no valid objections to the suggested deletion within the next week, I will go ahead and delete the image. Please comment. - mbeychok 06:56, 7 September 2007 (UTC)

Since there have been no objections of any kind to my proposed deletion of that image, I am deleting it. - mbeychok 18:25, 13 September 2007 (UTC)

[edit] Pulverizers, 5 of 6?

In the pulverizer section it states than a 500 MWe plant can have as much as 6 pulverizers as the one mentioned. However, it later mentions that only 5 of these feed the boiler. How come? What does the 6th one do?

I'm currently building a presentation explaining a coal power plant from A to Z. I am fairly familiar with this type of power plants. However, this pulverizer bit caught my eye. Anyone care to explain? Thanks! Alkaroth 18:58, 13 November 2007 (UTC)

Alkaroth, I assume that this is the sentence that you refer to: A 500 MWe plant will have six such pulverizers, five of which can supply coal to the furnace at 250 tons per hour under full load.

I would take that sentence to mean that 5 pulverizers can supply the coal needed at full load operation of the plant ... and the 6th pulverizer is an installed spare unit to be used in the event that one of the 5 operating pulverizers should require maintenance or repair. - mbeychok 19:49, 13 November 2007 (UTC)

mbeychok That's what I thought at first but decided to inquire just to be on the real safe side. Wouldn't want to get caught with my pants down! Again, thanks.

[edit] Simple facts

Some simple facts that would be very useful in this article, and are hard to find:

total number of power plants world wide, and also by type (gas/coal/oil/other?)
average/min/max size of a power plant of each type, by MW, and by CO2 emissions/other pollutants

prefereably near the top. this list could be bigger, I'm sure. --naught101 (talk) 00:00, 27 November 2007 (UTC)

I'll see what I can dig up ... might be tough. DJ Creamity^{Oh Yeah!} 21:16, 29 November 2007 (UTC)

I found a database over at carma.org, but it gives MWH, not MW capacity, it also does not differentiate between fuels: coal, gas, petcoke, wood, etcetera, or type. I will see if EPRI or Edison has anything. DJ Creamity^{Oh Yeah!} 21:44, 29 November 2007 (UTC)

This might become an estimation/extrapolation game from the data avaialable. DJ Creamity^{Oh Yeah!} 21:58, 29 November 2007 (UTC)

I found loads of Data for the US over at the DOE, I will figure the natural breaks in nameplate capacity, and type. DJ Creamity^{Oh Yeah!} 22:06, 29 November 2007 (UTC)

Here is what I got for the US, remember that this is rated capacity, not gross yearly production:

Type                          Rated Capacity     % total
Wind Turbine                    11334.4            1.05%
Solar                           411.4              0.04%
Petroleum Coke Fired Boiler     1754.4             0.16%
Oil Fired Boiler                34975              3.25%
Nuclear                         105584.9           9.82%
Natural Gas Fired Boiler        97632.8            9.08%
Internal Combustion Engine      8563.6             0.80%
Incinerator                     2671.3             0.25%
Hydroelectric                   96988.5            9.02%
Geothermal                      3170.9             0.29%
Fuel Oil                        956.1              0.09%
Combustion Turbine              155227.6          14.44%
Combined Cycle                  216269.6          20.11%
Coal Fired                      333115.2          30.98%
Biomass                         6259.7             0.58%

—Preceding unsigned comment added by DJ Creamity (talk • contribs) 23:13, 29 November 2007 (UTC)

nice work. fixed the table in your comment up.. --naught101 (talk) 12:30, 24 December 2007 (UTC)

It seems to me that the author(s) of this article describe a specific power plant--e.g., values of T and P are given for multiple points throughout the cycle, configurations of boiler/reheaters is included, and such. I think it should be made clearer that not ALL power plants operate at a boiler pressure of 3200 psia, etc etc etc. comment added by Usafharvey (talk • contribs) 19:29, 10 April 2008 (UTC)

It would also be nice to get some sort of knowledge up there of an estimate Kw/h cost for each fossil fuel type, if the data is available, anything I've found has been scattered about, some of you might have more luck 08:41, 25 April 2008

It would be tough to compare cost per kWH by fuel source because the differences would be small compared to the differences in the type of power plant - efficiency ranges over about a 2:1 value (antique coal plants vs. modern plants, vs. combined cycle large gas turbines), the cost is also affected by the capital cost of the plant, age, operating load factor, labor costs, and about a hundred other things. Costs have also changed by about a factor of 10 over the last 100 years alone. --Wtshymanski (talk) 18:10, 25 April 2008 (UTC)

[edit] Do coal plants scale back operations at night?

The Palo Verde Nuclear article says wholesale cost for hydro power is 63 cents, for nuclear $1.33, for coal $2.33 and for natural gas $4+. Given that electricity demand is lower at night I would think coal is used less at night and hydro and nuclear are used more. Is this true? Are there references somewhere? I googled without success. Thx, Daniel.Cardenas (talk) 00:16, 30 May 2008 (UTC)

Coal fired plants are not necessarily operated at a lower output at night. Many utility companies have gas turbine driven generators whose output can be much more easily adjusted to balance out the ups and downs of demand. - mbeychok (talk) 00:35, 31 May 2008 (UTC)

Nuclear is base load generation so its always on, day and night. Coal generation can be varied to suit demand, but there's a ramp up and ramp down time which can be up to a couple of hours IIRC (told to me when I visited Didcot power station) as it takes time to vary the steam pressure. The operator needs to balance out the wholesale price of electricity at that time, the cost of the coal being burned, the expectation of when demand will rise again, and the strain start-up and run-down puts on the plant (due to strain on the parts through varying temperatures). Gas fired generation can be started and stopped in a significantly shorter timescale. --Sunbite (talk) 06:35, 5 June 2008 (UTC)

Both coal and nuclear plants are considered base load generators. Their thermal output is slower to respond to changing electrical demand than peaking generators (such as natural gas fired or hydro turbines which take only a few minutes to ramp from idle to full power) because coal and nuclear both have to generate steam to drive turbines, which takes more time (it can take up to several hours for coal). That said, both coal and nuclear will scale back their loads at night due to the reduced demand. Neither runs full bore on a 24-hour basis because the demand just isn't there. --Blainster (talk) 08:05, 6 June 2008 (UTC)

To clarify my earlier comment on this subject, many utility companies in the USA that operate coal fired-plants also have gas-turbine generators. That permits them to operate the coal-fired plants at a fairly constant base load by using the gas-fired turbines to adjust for peaks in demand. The Tennessee Valley Authority system is one example. - mbeychok (talk) 00:36, 7 June 2008 (UTC)