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Front page image credit: Shutterstock
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What David alludes to is that, especially during very hot combustion reactions, dinitrogen gas from the air may react with oxygen to form NOx gases. So the formation of nitrous and nitric oxide is not necessarily prevented by burning methane.
My emphasis when I wrote the piece was on nitrogen- and sulfur-containing contaminants present in the coal, etc., being burned, which would not be present in pure methane gas.
Nice catch! Thanks!
You got it on the first try. ;)
Yes, I recognized that your "emphasis when [you] wrote the piece was on nitrogen- and sulfur-containing contaminants present in the coal, etc., being burned, which would not be present in pure methane gas." Unfortunately, in the case of oxides of nitrogen, the nitrogen "containing contaminants present in the coal, etc., being burned" is a miniscule, absolutely negligible contribution.
This is why burning hydrogen suffers from a similar pollution issue.
By the way, do you know the greenhouse gas equivalency of various oxides of nitrogen?
David
P.S. The greenhouse gas equivalency of water is also important, especially above the troposphere, where it cycles quite slowly.
Yes, NOx production from combustion, using air, depends very strongly on temperature (due to the endothermic character of this reaction). In fact, as you probably know, it depends so strongly that even small hot spots within the combustion zone can dominate the NOx production rate.
Now, I'm not certain, but I thought that some of the higher efficiency natural gas fired power plants use higher temperatures than coal fired power plants. After all, thermodynamic efficiency, even for turbines, increases with increasing temperature.
Of course, due to the strong temperature dependence of NOx production, good burner design can allow for lower NOx production even as average temperature increases, from one design to another (going toward "low NOx" burner designs).
So, unfortunately, the "state of the art" is an ever moving thing, and I'm not completely up on the state of this art.
David
I most certainly agree about the need for us "to stop all this crazy stone age like burning with hot flames". :)
In fact, I have felt like we have needed to get away from (as in ween ourselves off of) combustion energy sources ever since about the '70s. But, alas, no such good sense. :{
In fact, other than the transportation sector, and, perhaps, a few other areas (certainly almost all non-portable energy needs), I have felt like we have needed to ween ourselves off chemical energy sources—so little energy for so much "stuff" (fuel, etc.). But, alas, no such sense there either. :(
Yes, I've been watching fuel cell tech. for about a decade, now. Where I work, we even looked into the use of small hydrogen fuel cells, with the hydrogen stored in mettle matrices of whatever kind we could find that would work reasonably well, as a supplemental energy source for our more remote monitoring sites. Unfortunately, it was not sufficiently reliable, at the time. :/
David
Very nice. :)
Of course, as I'm sure you know, another important aspect is the dialectric that separates the air/oxygen side from the fuel side. The fuel cells you linked to use a thin-film solid-oxide, so it is a (reasonably) good oxygen ion transport dialectric, as opposed to the proton transport dialectrics of hydrogen fuel cells. With oxygen ion transport, as I'm certain you are aware, one has far greater fuel flexibility.
It looks like we are getting the technology in line, little by little. Of course, that's typically how science and technology progress.
I look forward to being able to see society ween itself off combustion energy technologies. :)
David
You are correct that, at this time, using fuel cells doesn't look like a solution for air travel. However, we are far from having fuel cell solutions for a many more issues than just air transport.
The fact is that at just about any point in aviation history there have been technologies, and/or achievements that have appeared impractical or even impossible; but were nonetheless subsequently realized. Will fuel cell powered aircraft be among them? I don't know, at this time. The technology is too immature.
David
Was that an average over the different fuel sectors, or new vs. new? (Of course, there haven't been many new coal fired plants proposed, of late, and even many of the earlier ones that were permitted haven't been built, and will not be built so long as natural gas is so inexpensive. So cheep natural gas does have its benefit. [Coal has other detrimental affects, besides just NOx, SO2, and such. The ash is horrid stuff.])
David
I don't think this is so; as what is the ideal temp of earth, what is ideal amount of CO2
Most who are in favor of similar premises state the ideals are some where in line with pre-industrial era
But that is a large presumption
The cost of CO2 sequestration is huge, yet the cost/benefit is very incomplete
The cost/benefit of other means of lowering or even just slowing the temp increase are also incomplete
The author notes that the economics favor extracting future large-scale methane extraction from below permafrost and from continental shelves. I think that remains yet to be seen but let's assume that is the case. But where is the argument that switching to renewable energy sources prematurely would be the better course of action? The unstated assumption is that solar, wind, etc. are "clean" sources of energy -- non-harmful to the environment. I doubt that is the case even now; how much worse will the environmental impact be when these sources of energy generation are scaled up by a factor of ten or thirty?
And how bad will the financial impact be on the indigent of the world -- families that can hardly afford their electrical bill even today, even in developed nations? If the answer is, yet more economic redistribution imposed on the middle class, then I am afraid these proposals are poorly thought through.
You are also out of touch with the financial impact in developing countries. In many places in the 3rd world not connected to the grid, renewables are either the cheapest or the only way to get electricity. That is only going to get better as renewables are expanded and continue along their cost reduction curve. Even where there is a grid, solar is now cheaper than diesel generated electricity in developing countries, making these exact families lives better. Like many people you are not up with how the massive drop in price in solar lately has changed much of the picture. There is no reason for that trend not to continue also.




You say (emphasis added):
Where do you think the nitrogen oxides come from when burning coal or petroleum? (The other emphasized word in your quote is a hint, though only a hint.)
David