Wikipedia:Reference desk/Archives/Science/2016 April 20

= April 20 =

Why did "clean coal" turn out to be so slow and expensive to develop?
I understand that there are serious unknowns about carbon sequestration and "clean coal". But I have to admit - when I first heard of the idea, I assumed someone would have an existing coal plant, drill a deep hole (and frack it), set up a pump to compress the exhaust and drive it underground ... and see what happened. At least you would smell no pollution today. So why didn't this zero-generation version of the process happen? Wnt (talk) 00:03, 20 April 2016 (UTC)


 * Why do you think it has not happened? See Carbon capture and storage. --Guy Macon (talk) 08:11, 20 April 2016 (UTC)


 * My cynical mind says that "clean coal" is just a marketing canard created (or rather repurposed) by the coal industry to keep coal burning alive longer. While it is not impossible to extract CO2 (and other pollutants - sulfur, particulates, ...) from flue gases, it's far from trivial to do so efficiently and cost-effectively - around 2/3rds is plain old nitrogen that needs to be separated out. If the proposed sequestration techniques for CO2 are long-term stable is a very much open question. In other words, without the atmosphere as a free dump, coal burning is unlikely to be cost effective. --Stephan Schulz (talk) 11:15, 21 April 2016 (UTC)


 * Honestly, I just pictured them taking the whole stack, nitrogen and other pollutants included, injecting it deep in whatever ground happened to be nearby, and hoping that/"researching whether" the carbon dioxide would react with something or at least dissolve into water long-term as it does in the ocean. Not saying this would be pretty or satisfactory ... just that it seems like a quick and dirty way to cap the stacks. Wnt (talk) 11:59, 21 April 2016 (UTC)


 * The oil price dropped dramatically, killing the economic viability of clean coal. Roger (Dodger67) (talk) 11:18, 21 April 2016 (UTC)
 * Coal is just not a very clean fuel in general. It has a whole host of things other than carbon that you need to keep from getting into the atmosphere (mercury is #1 on this list, but also other elements subject to emissions limits like arsenic and selenium) and it leaves ash full of all the non-combustible stuff that you have to get rid of somehow (which can be an environmental issue in itself, see Kingston Fossil Plant coal fly ash slurry spill for example). It's also less carbon efficient than oil or natural gas, each of which have much fewer of the other problems I mentioned with coal.
 * (Yes, I know, oil and gas have their own environmental problems.) shoy (reactions) 12:52, 21 April 2016 (UTC)


 * Compressing all of that gas and pumping it far away and deep underground is a hideously costly (and energy intense) process. You'd have to generate considerably more energy to cover the cost of sequestering the CO2 - and that just means that you have even more CO2 to sequester.  Problems like that can very easily spiral out of control to the point that it becomes impossible to "win".  One study showed that merely compressing the CO2 cost 25% of the power produced by the coal plant.  If you also have to transport the compressed gasses to a convenient deep storage location, that number would increase substantially.  Every ton of coal makes much, much more than a ton of CO2 - and if you aren't separating out the nitrogen and other gasses, it'll be immensely more than a ton.   Now imagine the L-O-N-G coal trains bringing coal in - and imagine several times that number of waste gas trains hauling it away again! SteveBaker (talk) 05:27, 22 April 2016 (UTC)

Pot seasoning
No, this isn't about edibles...

There's been some concern in recent years about Teflon-based nonstick pots and pans, specifically with regard to the possible health effects of perfluorooctanoic acid (PFOA). In response, some people are returning to stainless steel.

But stainless has a severe sticking problem when new. To make it usable, one suggestion is to "season" the pot. You get it hot and add a bit of some high-smoke-point vegetable oil, swirl it around, let it cool, then wipe it out with paper towels rather than wash it. The oil leaves a residue on the pot, sort of a hard plastic, and now it's much less sticky.

The thing is, though, that seasoning is made of something. What, exactly? Does it contain, say, polycyclic aromatic hydrocarbons (PAHs)? Has anyone done a study comparing the possible effects of PFOA with whatever the more-whole-foodsy "seasoning" is made of? --Trovatore (talk) 05:54, 20 April 2016 (UTC)
 * Seasoning (cookware) seems to give one a decent start in researching the topic. Some of the references look promising as well.  -- Jayron 32 08:51, 20 April 2016 (UTC)


 * Wait, what? Seasoning is usually only discussed for cast-iron cookware. Our article also mentions carbon steel, but outside of woks I don't think that's very commonly used. Stainless doesn't really take the polymerization layer because it's non-porous. See e.g. this thread . I mean, sure, I guess you can do it to stainless steel, I just highly doubt the efficacy and that you're actually getting much of a persistent film. As for the new stainless being stickier when new - maybe you're just polishing your pots over a few uses so that they get smoother? But back to the question: the idea of seasoning is to cross-link and polymerize the oil. I cannot find anything scholarly on the health effects of this film. This patent says that in addition to the polymer film, there is magnetite black oxide in/below the seasoning layer. The one thing I've heard recently about cast-iron cookware is the health benefits, e.g. here  and the lucky iron fish. Finally, PAH seem to only form in low-oxygen scenarios. So as long as you're seasoning in normal conditions, I don't think you'll be creating them from cooking oils. SemanticMantis (talk) 14:30, 20 April 2016 (UTC)
 * Hmm, well, the interblags seem to think you can do it. See for example here and search for the reply by "cheflars".  I tried it and it worked.  Admittedly it wasn't a well-controlled experiment, because that wasn't the only thing I changed &mdash; I also used less butter and lower heat.  I'll try the seasoned pan with high heat and more butter just to see what happens. --Trovatore (talk) 18:13, 20 April 2016 (UTC)


 * Don't know about the salt's role in it (see your source) but one point is, to my knowledge, to prevent mineral and other deposits to build up as those add to the stickyness in all types of cookware.--TMCk (talk) 18:27, 20 April 2016 (UTC)


 * Oh, I get it now, thanks. That person calls it "quick season", I think to differentiate it from what we do to cast iron. That method seems to be intended as a limited use "seasoning", which will need to be reapplied every few uses, in stark contrast to the hard shiny layer on my cast iron, which can't be done in a few minutes, and can last indefinitely with proper care use. So while you can do a similar thing to "season" stainless steal, it's rather different effect. SemanticMantis (talk) 18:50, 20 April 2016 (UTC)
 * OK, just tried it. I'd call it mostly a success.  With the egg going into the soup of bubbling butter (with garlic and habanero slices there before the egg, of course), the egg white bubbled the way I remember it doing back when the pan was unbearably sticky.  It came out with a little more difficulty than with the lower heat, but still I was able to get it out without breaking the yolk, which I never could pre-seasoning.  Then cleanup without soap was also a little more challenging than the lower-heat trials, but I did manage.
 * Not claiming this is valid science, but taking the above observations together with the visual appearance of the film, I'm reasonably convinced. --Trovatore (talk) 18:44, 20 April 2016 (UTC)
 * Extra iron has health benefits for people who are iron-deficient, but it can be detrimental to the health of normal people, especially middle aged men and post menopausal women. Older people are advised to avoid using cast iron pots and definitely not to use iron supplements.    CodeTalker (talk) 16:53, 20 April 2016 (UTC)


 * I don't find that kind of health advise in the source you've provided. Could you point it out?--TMCk (talk) 17:15, 20 April 2016 (UTC)


 * You're right, the source doesn't specifically recommend against excess iron, it just shows that excess iron can cause bone loss. For more specific recommendations against iron supplementation, see, , .  CodeTalker (talk) 19:32, 20 April 2016 (UTC)


 * Restriction of supplemental intake makes of course sense but I was wondering about the "avoid cast iron pots" advise. How much iron would be absorbed by the food under normal cooking conditions?--TMCk (talk) 19:46, 20 April 2016 (UTC)
 * Spelling whinge: "Advise" is a verb; "advice" is a noun. --Trovatore (talk) 20:09, 20 April 2016 (UTC)
 * Tho wy don'd yuh thainge id?--TMCk (talk) 20:31, 20 April 2016 (UTC)


 * This article references a 1991 study in Journal of Food Science that showed that spaghetti sauce cooked in cast iron absorbed 2 mg of iron per 100 g of sauce, and applesauce absorbed 6 mg.  Given that 100 g is a pretty small serving and that the daily recommended allowance of iron for men is 8 mg, this seems fairly significant. CodeTalker (talk) 20:28, 20 April 2016 (UTC)


 * Interesting. So avoid cooking acidic food in cast iron pans & pots if you need to watch your iron intake.--TMCk (talk) 20:34, 20 April 2016 (UTC)
 * and That result is not typical of cooking general things in cast iron, and that is even mentioned in the blurb linked. In more detail: tomato sauce is acidic, and will both break down the seasoning on the pan as well as etch the iron. Also, it is reported that the tomato sauce becomes darker colored than it would in e.g. stainless steel. For this reason, the general advice is to not cook tomatoes, lemon juice, vinegar, or anything else acidic in cast iron cookware. E.g. here  they say to "avoid overly acidic foods in our cast irons. On the same token, it’s best not to deglaze a cast iron with vinegar or wine". SemanticMantis (talk) 20:59, 20 April 2016 (UTC)


 * Yes, and that's why I said "acidic food" above.--TMCk (talk) 21:24, 20 April 2016 (UTC) PS: I am Tracy ;) --TMCk (talk) 21:26, 20 April 2016 (UTC)


 * A couple suggestions:


 * 1) Ceramic coatings can provide excellent non-stick surfaces with no need to season. They are scratch resistant, but can crack.


 * 2) This issue only comes up when cooking at high temperature, as in frying. Since this is unhealthy anyway, I've decided to cook at lower temperatures, such as boiling water.  For example, I don't fry salmon, I boil it in soup.  While I made this change for health reasons, a side benefit is that the pot is much easier to clean than a frying pan. StuRat (talk) 17:40, 20 April 2016 (UTC)


 * From our PTFE article: "While PTFE is stable and nontoxic at lower temperatures, it begins to deteriorate after the temperature of cookware reaches about 260 °C (500 °F), and decomposes above 350 °C (662 °F).[39] The degradation by-products can be lethal to birds,[40] and can cause flu-like symptoms[41] in humans. See polymer fume fever." StuRat (talk) 18:46, 20 April 2016 (UTC)


 * Frying or boiling salmon?  IMHO there's only one respectful way to treat a nice piece of salmon, and that's to broil it, gently, so it's still translucent in the middle.  However canned salmon can be nice in a scramble, with capers. --19:17, 20 April 2016 (UTC)


 * I make a nice salmon chili with boiled salmon. I tried canned salmon once, and it had a spine in it.  Yuk ! StuRat (talk) 00:41, 21 April 2016 (UTC)


 * It might be good, but it just seems like a waste of fresh salmon. I bet you couldn't really tell the difference if you used canned, except for the spines, which in my experience soften in the cans to the point that they're harmless.  Just like you don't use top-shelf whiskey for a Manhattan. --Trovatore (talk) 05:27, 21 April 2016 (UTC)


 * I eat salmon because it's healthy, and I get it for $4 a pound, eating a $1, 4 oz portion with each meal. So, I'm not exactly breaking the bank. StuRat (talk) 15:07, 21 April 2016 (UTC)


 * And then it goes on saying: "Meat is usually fried between 204 and 232 °C (399 and 450 °F), and most oils start to smoke before a temperature of 260 °C (500 °F) is reached,..."--TMCk (talk) 19:13, 20 April 2016 (UTC)


 * Right, and if the pan was fully submerged in oils with a low smoke point and kept below that smoke point, that would keep it at a safe temperature. But, the pan only has oil in the bottom, allowing the area above the oil to get hotter from heat that rises around the edge (especially on gas stoves on high) and higher temp oils may be used, and the pan may be left on the stove too long and smoke or even burn dry.  (This can also happen when boiling in water, but I use a microwave oven to boil my salmon chili, which has a timer so I don't have to worry about that.) StuRat (talk) 00:41, 21 April 2016 (UTC)


 * Yes, microwave is likely the safest way for you. Stick to it.--TMCk (talk) 01:37, 21 April 2016 (UTC)


 * And are we to assume that you've never left a pan on the stove too long and burnt something ? StuRat (talk) 01:59, 21 April 2016 (UTC)


 * Rarely! I'm still allowed to prepare meals at the stove and not condemned to microwave "cooking". Hah.--TMCk (talk) 02:13, 21 April 2016 (UTC)


 * It was rare for me, too, but just a few times destroying a pan and having to open all the windows in January to air out the smoke were enough for me to avoid it. I never understood why stove burners don't have timers on them.  It would be trivially easy on an electric stove, and just a bit harder for gas.  StuRat (talk) 02:53, 21 April 2016 (UTC)


 * Maybe you should try something more simple/less dangerous for you and your surrounding like an Easy-Bake Oven?--TMCk (talk) 03:52, 21 April 2016 (UTC)


 * This seems like a backward attitude. Undeniably kitchen fires happen and people die from it.  A timer, or a simple device to check for the extraordinary heating that occurs in a dry pot rather than a wet one, or a physically linked smoke analyser (I won't say "detector" because I mean something that responds to serious and user-configurable amounts of smoke only, not a bureaucratically defined object), or even a photodiode looking for the flicker of fire might all potentially offer some protection (but I think the thermometer is the most practical idea).  I feel like any good, obvious idea doesn't get done until there is a way to link it up to the Internet and have the NSA tracking your every move, at which point they say woo-hoo, we'll give you some features you wanted for 50 years, and all you have to do is agree 1984 is a damn good idea! Wnt (talk) 12:08, 21 April 2016 (UTC)


 * I agree (except for the NSA part). Cooking methods that don't shut off automatically should be banned, as the risk of fire is obvious. StuRat (talk) 15:11, 21 April 2016 (UTC)


 * I didn't say I wanted those banned; I just agree we should have better things on the market. Wnt (talk) 15:52, 21 April 2016 (UTC)


 * @Stu: Put your stove on a timer or even better, turn off your electricity and ban every little thing that could pose ANY risk at all but don't try to restrict everybody else just to protect the fools and the overly scared.--TMCk (talk) 16:00, 21 April 2016 (UTC)


 * My stove is gas, and, as I already stated, I've solved the problem by using a microwave to cook. I also have a portable electric convection oven, with a timer, for foods that require browning. StuRat (talk) 16:50, 21 April 2016 (UTC)


 * Question: I don't know, but I'm thinking stainless steel pots also work by passivation of a mostly-not-chrome metal into a mostly-chrome surface. Does the chrome have different adhesive properties than the steel?  (I easily picture the vegetable oil works short-term but I don't know whether it can account for the long-term change) Wnt (talk) 12:09, 21 April 2016 (UTC)


 * Very good point. Don't know the answer but I just learned something.--TMCk (talk) 14:22, 21 April 2016 (UTC)


 * Here's a nice (promotional) write up about passivation of stainless as an intentional industrial process increase natural passivity. However here is a great documentary showing that stainless steel is also self-passivizing. The relevant bits start around 2:40 but the whole thing is probably worth it for the narrator, graphics, and music :) As for friction/adhesion, it seems chrome oxide is slipperier than steel, and "The coefficient of friction of hard chromium against hard metals are generally the lowest of any electrochemically deposited coatings."  SemanticMantis (talk) 15:03, 21 April 2016 (UTC)

Salt and sweating
If you eat a lot of salt but live in a hot place where you sweat out a lot of salt, does eating a lot of salt still hurt your body? Anna Frodesiak (talk) 06:15, 20 April 2016 (UTC)


 * The answer in general is: the more you sweat (like an athlete who trains regularly), the more salt you need in your diet, compared to someone who does not sweat a lot. However, I'm not sure that people in hot climates generally sweat a lot more than other people, people who live in hot climates are more acclimatized to the heat, wear less clothes, stay out of the sun, avoid strenuous activity during the hottest parts of the day, etc... Vespine (talk) 06:31, 20 April 2016 (UTC)


 * Hi Vespine. That doesn't quite answer the question. Let me be specific: Me. I live in Haikou. It's hot in the summer. I sweat a lot because it's broiling hot. I eat lots of salt year round. Is the salt I eat in the summer less harmful than the salt I eat in the winter. Anna Frodesiak (talk) 07:22, 20 April 2016 (UTC)


 * What makes you think that salt is harmful? See Salt and cardiovascular disease. --Guy Macon (talk) 08:06, 20 April 2016 (UTC)


 * A tad disingenuous, maybe? For decades we've all been told of the health risks of too much salt.  With all the conflicting health advice we get these days, it's not surprising if not everyone is up with the latest breathless revelations.  And they may still not be up to speed by the time the next contradictory report comes along, restoring the status quo.  Lesson: If you stay out of touch for long enough, you'll get back in touch again.  Nothing new under the sun. --   Jack of Oz   [pleasantries]  09:53, 20 April 2016 (UTC)


 * Hi Guy. Isn't that cherry-picking a bit? That bit called Salt and cardiovascular disease is about the only non-negative thing about salt in that article. Plus, there is all the negative stuff at Health effects of salt. Anna Frodesiak (talk) 10:13, 20 April 2016 (UTC)


 * Admittedly, it seems almost like a fringe opinion. Nonetheless, I think it deserves consideration!  The central issue there is whether the health effects of salt represent causation or correlation.  Personally, I am biased because of an incident that happened in my 20s.  Over a few weeks I kept feeling more and more desire for salt, yet found it less and less satisfying ... eventually the salt even seemed to have a sour undertone, and I started thinking something was wrong with it.  After some false ideas, I happened on a potassium salt substitute and it was just ... heavenly.  Exactly the flavor I was looking for, extraordinarily satisfying, and that was the end of it.  And so I wonder whether people who consume more salt are simply hungry for potassium but eating the wrong thing, and whether then it might make more sense to focus on potassium supplementation than cutting sodium.  (A touch of epsom salt every now and then feels very nice to me also) Wnt (talk) 11:52, 20 April 2016 (UTC)


 * I don't believe your case is typical. I find potassium chloride to be repulsive (only acceptable in small amounts), and absolutely hate it when something sold as "low sodium" has that added in it's place.  I just want low sodium foods with nothing else added.  Also, if you find regular table salt sour, that might be the added iodine.  You can buy noniodized salt, but beware that you might not get enough iodine then. StuRat (talk) 17:28, 20 April 2016 (UTC)


 * Oddly enough, that was the first thing I tried during that period - but the fresh container of non-iodized salt seemed exactly as sour and unsatisfying. The sense of sourness went away almost entirely once I had balanced myself out a bit with potassium, though I am faintly aware of it to this day if I really think about it.  The salt I use routinely is a "salt lite" (50% potassium 50% sodium); the two flavors complement each other well and it comes in bigger cheaper handier containers.  The way I think of it, "salt" is a generic term for a mixture of ions, and sodium sits just a little to the sour side of the spectrum within it. Wnt (talk) 01:08, 21 April 2016 (UTC)


 * That's probably good, since most people get too much sodium and too little potassium. You might also try high potassium foods, like bananas. StuRat (talk) 01:14, 21 April 2016 (UTC)


 * See Human_homeostasis. Unless you're talking about extreme conditions where there is something preventing your body reaching homeostasis (like drinking seawater) your body will just sort itself out. 196.213.35.146 (talk) 12:38, 20 April 2016 (UTC)


 * Eventually, yes, but the problem is that the elevated sodium level can cause damage until it's corrected. Just a bit of damage each time, to be sure, but it's cumulative. StuRat (talk) 01:12, 21 April 2016 (UTC)


 * In general, people will adapt to heat, and after a few days or weeks, will excrete less salt with the sweat. So yes, you may need more salt intake in hotter climate, but the effect will be mostly temporary, and will be less than naively expected. --Stephan Schulz (talk) 13:11, 20 April 2016 (UTC)


 * That makes sense, and is what I would have guessed. But I don't know for sure, and I have no refs to back this idea up. Anyone else want to try to find refs along these lines? SemanticMantis (talk) 14:10, 20 April 2016 (UTC)


 * Ok this is highly relevant (but paywalled), says "the data are best explained in terms of an active regulation of sweat composition" -- but that is with regard to exercise at different temps, not acclimatization effects. Here are some freely accessible papers: this one  is about sodium intake and sweat composition, and this  is about sodium secretion and re-absorption more basically. Note the last one is from 1965, and the first link (1982) may supercede some of the notions presented in the earlier paper. SemanticMantis (talk) 16:52, 20 April 2016 (UTC)


 * OR: I have sodium sensitive hypertension, as do my brothers (but oddly, neither of our parents). I've come to the conclusion that it's not so much sodium I consume, per see, but how much I consume relative to the amount of water I consume.  So, if I drink more water (which I will need to, if sweating profusely), then I can consume more salt. StuRat (talk) 17:23, 20 April 2016 (UTC)


 * This entire thread seems like medical advice to me, which we don't provide here. I'm not bold enough to remove it myself, but perhaps someone else is. --69.159.61.172 (talk) 19:28, 20 April 2016 (UTC)


 * We have an unofficial guideline called Kainaw's criterion. I don't see any response that says anything about treatment, medical diagnosis, or prognosis. What I see are references to WP articles and scholarly literature about the human body and biological processes. We should not give medical advice, but we are allowed to give biological information. If you do see a response that offers suggestions for treatment, diagnosis, or prognosis, please do remove them. SemanticMantis (talk) 20:09, 20 April 2016 (UTC)

This is certainly not medical advice to me. I don't give a hoot about salt. This follows an off-wiki discussion about how the body works. I said I'd post here and ask so I could say "Ha!" to someone.

In a nutshell, what I am asking is if salt does do some harm to arteries or kidneys etc. before it is peed out, is it disposed of better or earlier or less harmfully by sweating?. I mean, does it never see kidneys on the way. Do you see what I mean? And thank you all for the good information (so far). Anna Frodesiak (talk) 01:31, 21 April 2016 (UTC)