Right, you get mostly SO2 upon primary combustion of sulfur, plus some SO3. And it will mostly end up in the atmosphere as sulfuric acid.
Methylmercaptan and methanthiol are both acceptable names for a nasty smelling compound. And its detectability by smell at even very low concentrations is the main reason for its use.
Even though it smells bad, it would be a safety factor for CNG fueled cars, just as it is for home natural gas applications. If you have a leak, you know it.
Gasoline fumes smell bad enough, but there are some very serious health issues involved with them. You may remember a company, years ago, that sold gasoline containing "Platformate", which the American public would assume, naturally, was good stuff.
Platformate came from the platinum catalytic reformers, and was basically benzene-toluene-xylene. Anyone who doesnt already know the consequences of inhalation, ingestion, or absorption of those items can look up the MSDS's.
Yeah, it's a fuel that doesn't scale down that well, nor lend itself to ease of unplanned arbitrary trips. Buses are a great application. They put big tanks of it on the roof, where (aside from the capacity) leaks are not so immediately and vividly dangerous, and they bring 'em back to the barn after a highly predictable span of miles and hours for refueling. You lose power as well as range; you don't care as much if you have a big engine and/or you most of your operations involve a top speed of 35 or 40 mph and a stop every two or three blocks. I've ridden on CNG buses. It is a stately experience even compared to a similar diesel bus. On the other hand, it doesn't sound or smell like a diesel bus.
It also has some applications with fleet vehicles. I guess a government Crown Vic is the next best thing to a bus. If you were going to install a gray-market conversion kit (I think the EPA and probably some safety agency in the US look askance at late 70s style do-it-yourself CNG conversions; there are, I think, four certified vendors), you'd prefer a larger vehicle.
Physically, that is. Economically, fuggeddaboutit. The numbers just don't work out in a country where gasoline is cheap. There are parts of the world where CNG has really made inroads into personal and commercial road vehicles, but in the US it remains a niche market. The premium rig in those countries is a "dual fuel" vehicle that retains a user selectable ability to run on gasoline or diesel.
To refuel at home, you'd need a small compression appliance to boost the few pounds per square inch of a domestic natural gas supply into the "not for the faint of heart" pressure of the vehicle tanks. In commercial applications, at least, they require periodic inspection.
From a maintenance/longevity standpoint it's great. Burns *much* cleaner than gasoline or even propane. Helps with pollution, too. Some companies are switching to CNG from propane to run their fork trucks and other material handlers in warehouses and so forth, mostly because of the lowest carbon monoxide emissions you're going to get short of a pure electric.
Yeah, hydrogen sulfide is something they remove from natural gas fairly far upstream in the system. There can be quite a lot of it in some regions, and it's nasty stuff -- strongly poisonous to workers in several ways, and corrosive to equipment. Natural gas with this and various other contaminants (notably CO2) being known as "sour," this process is called "sweetening." (I've read that this is actually how we usually obtain H2S and has emerged as a prominent minority source of sulfur, part of a combined economic and environmental trend toward using or at least capturing byproducts rather than flaring or venting them off.)
There *are* mercaptan/sulfide blends used as fuel gas odorants. I think it's usually dimethyl sulfide, though, not H2S.
I'm told that all of the related chemicals used for this purpose are chemically similar to one of the active ingredients in a skunk's gesture of unwelcome, and can be detected by the human nose somewhere around 10 parts per billion. People started putting in odorants after a 1937 catastrophe in which a school blew up with some hundreds of students and teachers in it.
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Fuel gases being transported without an odorant are prominently marked. It's *supposed* to make a nasty smell in low quantities. That having been said, I've never found the exhaust smell of propane or CNG vehicles objectionable, though it's always easy to tell when there's a propane forklift working in one's vicinity. If you're chronically getting that distinctive skunk smell, you've got a leak and need to do something about it.
I believe skunks do butyl mercaptans. The dialkyldisulfides are the other compound you are referring to. There is sometimes a little problem with the nomenclature between sulfides and disulfides.
They all stink (as the joke goes.)
H2S can be very corrosive. The mercaptans are much less corrosive, under most system conditions.
Now, as a guy who loves Heinekin, sulfides are not always bad.
True, but perhaps a bit too much of an appeal to a rhetorical detail. It does appear that polar ice *caps* and sea ice in the Arctic are diminishing amid a general warming trend (as are glaciers).
There are legitimate debates over whether (a) this is anthropogenic, (b) whether we can reasonably do anything about it, and (c) whether it is on the dismal side of the decimal point compared to what nature has done to us before and will do to us again through planetary or astrophysical mechanisms (there are many hypotheses but AFAIK no proof or even consensus about the Big Picture stuff and its apparent cyclic nature).
But things are getting warmer than they've been in a while, and as we know from complexity theory, we are likely to encounter not only gradual changes but (at unpredictable points) snap changes if the trend continues. (For values of "snap" that are orders of magnitude less snappy than the few weeks favored by Hollywood, of course, but on a geological time scale, still pretty fast. )
There is a guy in Hawaii who is growing some of those Diesel Fuel Trees.Brazilians also run a lot of their vehicles on Sugar/Alcohol/whatever. I reckon they are doing something right. cuhulin
^^^^^^^^^^^^^^^^^^^^^ Global warming takes a break
Lorne Gunter, National Post Published: Friday, September 11, 2009
Imagine if Pope Benedict gave a speech saying the Catholic Church has had it wrong all these centuries; there is no reason priests shouldn't marry. That might generate the odd headline, no?
When a leading proponent for one point of view suddenly starts batting for the other side, it's usually newsworthy.
So why was a speech last week by Mojib Latif of Germany's Leibniz Institute not give more prominence?
Prof. Latif is one of the leading climate modellers in the world. He is the recipient of several international climate-study prizes and a lead author for the United Nations' Intergovernmental Panel on Climate Change (IPCC). He has contributed significantly to the IPCC's last two five-year reports that have stated unequivocally that man-made greenhouse emissions are causing the planet to warm dangerously.
Yet last week in Geneva, at the UN's World Climate Conference -- an annual gathering of the so-called "scientific consensus" on man-made climate change -- Prof. Latif conceded the Earth has not warmed for nearly a decade and that we are likely entering "one or even two decades during which temperatures cool."
The global warming theory has been based all along on the idea that the Atlantic and Pacific Oceans would absorb much of the greenhouse warming caused by a rise in man-made carbon dioxide, then they would let off that heat and warm the atmosphere and the land.
But as Prof. Latif pointed out, the Atlantic, and particularly the North Atlantic, has been cooling instead. And it looks set to continue a cooling phase for 10 to 20 more years. "How much?" he wondered before the assembled delegates. "The jury is still out."
But it is increasingly clear that global warming is on hiatus for the time being. And that is not what the UN, the alarmist scientists or environmentalists predicted. For the past dozen years, since the Kyoto accords were signed in 1997, it has been beaten into our heads with the force and repetition of the rowing drum on a slave galley that the Earth is warming and will continue to warm rapidly through this century until we reach deadly temperatures around 2100.
While they deny it now, the facts to the contrary are staring them in the face: None of the alarmist drummers every predicted anything like a
30-year pause in their apocalyptic scenario.
Prof. Latif says he expects warming to resume in 2020 or 2030. "People will say this is global warming disappearing," he added. According to him, that is not the case. "I am not one of the skeptics," he insisted. "However, we have to ask the nasty questions ourselves or other people will do it."
In the past year, two other groups of scientists -- one, like Prof. Latif, in Germany, the second in the United States -- have come to the same conclusion: Warming is on hold, likely because of a cooling of the Earth's upper oceans. It will resume, though, some day.
But how is that knowable? How can Prof. Latif and the others state with certainty that after this long and unforeseen cooling, dangerous man-made heating will resume? They failed to observe the current cooling for years after it had begun, how then can their predictions for the resumption of dangerous warming be trusted?
My point is they cannot.
It's true the supercomputer models Prof. Latif and other modellers rely on for their dire predictions are becoming more accurate. A major breakthrough last year in the modelling of past ocean currents finally enabled the computers to recreate the climate history of the 20th century (mostly) correctly.
But getting the future equally correct is far trickier. Chances are some unforeseen future changes to real-world climate or further modifications to the UN's climate computers will throw the current predictions out of whack long before the forecast resumption of warming.
I'm not sure I'm comfortable with them burning down the rain forest to grow sugar cane for fuel... Seems like every potential alt fuel solution is a double edged sword... Ben
I have been to Cardston,Alberta,Canada in 1956 and Tokyo and Hong Kong and a year in the Nam in 1964 and I once visited Mexico in 1992 or 1993 for five days. Does that mean I am a World Citizen? cuhulin
Another theory occurs to me after some web browsing: if you're in the habit of running your tanks down to their last gasp, an extra helping of odorant that had been clinging to the walls may come out. (But if you notice this in the trunk or the cabin rather than around the exhaust, look into it.)
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