All this talk of smoke from steam locomotives brings me to ask a curiosity question. If you have, Oh let's say, a 75 car train pulled by one steam locomotive capable of the task vs the same train pulled by diesels (probably would require several diesel units) which one produces more pollution? It is obvious which one produces the more visible results but which one is actually worse? Any studies ever done on this?

Strasburg Rail Road
asholley@hotmail.com

That may depend on how both are maintained and operated, but if both are "tuned-up" with good fuel and operators, I would say that the Diesels would still fare much better. The Diesel exhaust is generally cleaner for the visible and invisiable emissions and there is much less of it than in a steamer. The Diesel fuel today is lower in sulphur than most soft coals consumed in locomotives today (unless somebody is burning low-sulphur and low BTU coal from the Powder River mines in WY).

With a Diesel, you burn a relatively low quantity of high grade fuel, while a steamer burns a high quantity of low grade fuel.

A better comparison may be a Diesel vs. an oil burner with both buring #2. Both situations have varying ratios of fuel and air for combustion.

Remember the thermal efficency of both machines. Fuel has to be burned to make power. The less effiecient one will have to burn more fuel and make more emissions to get the same work done at the drawbar.

> All this talk of smoke from steam
> locomotives brings me to ask a curiosity
> question. If you have, Oh let's say, a 75
> car train pulled by one steam locomotive
> capable of the task vs the same train pulled
> by diesels (probably would require several
> diesel units) which one produces more
> pollution? It is obvious which one produces
> the more visible results but which one is
> actually worse? Any studies ever done on
> this?

I don't think there have been any studies but a couple issues jump to mind. First the modern diesel is running more than twice the efficiency as the traditional steam engine. So for a given BTU produced, twice as much fuel is required for a traditional steam engine. That doesn't consider the lack of efficiency for converting the BTU into work. On the other hand, because the steam engine is an external combustion engine, it produces less of the nitrogen based haze pollutants than an IC engine. The biggest strike against the steam engine is that when burning coal, nearly all the oxidized fuel winds up as CO2, a green house gas. Where as the petroleum products have varying amounts of hydrogen combustion so they produce less CO2 and carbon monoxide.

Mr. Porta addressed these problems with his Gas Producing Combustion System (GPCS) appears to give the conventional steam engine a real boost in the efficiency department. Based on some Men of Iron shows of the two South African two footer Garretts, it also appears to greatly reduce smoke emissions. From the tapes I've seen of various engines equipped with Porta's GPCS, the stack produce about as much smoke as a diesel locomotive. Perhaps we have a cue here for either Hugh Odom as the chronicler of Mr. Porta's efforts or Ross Rowland of the ACE project to offer some thoughts about steam efficiency during the period of declining oil reserves.

There is also an interesting article in the May 2004, Scientific American "Questions About the Hydrogen Economy" which looks at not only the vehicle efficiency and pollution but the efficiency and pollution produced by the supply chain to deliver the energy to vehicle. Unfortunately, it doesn't cover a return to coal and steam in the railroad segment of the transportation industry.

Ed


ff1044@aol.com

> All this talk of smoke from steam
> locomotives brings me to ask a curiosity
> question. If you have, Oh let's say, a 75
> car train pulled by one steam locomotive
> capable of the task vs the same train pulled
> by diesels (probably would require several
> diesel units) which one produces more
> pollution? It is obvious which one produces
> the more visible results but which one is
> actually worse? Any studies ever done on
> this?

Aaron, I remember reading somewhere that in terms of human toxicity, diesel fumes are much worse than coal. If I recall the article correctly, the combustion of produces nitrogen compounds that are known carcinogenic agents. I assume that comparison was to bituminous, not anthracite and its higher silicate content.

Is there a doctor or a scientist in the house?

Of course, worse depends on your criteria.

I tend to think that one of the great dangers to the future of railroad (and industrial) preservation as well as rational thinking is that children are sitting in classrooms right now being told that climate change is unidirectional, recent and unnatural and directly and exclusively caused by humanity.(they aren't sophisticaticated wonder about genesis of the ice ages or old enough to remember the dire predictions of planetary cooling in the 1970's).



Superheater62@yahoo.com

I wish I could put my hands on the sales literature I got from SLM showing how their new generation of steam locomotives (late 1990's) polluted less than currently operating diesels using their light oil firing system etc. I believe steam put out higher quantities of something relatively innocous but diesels put out higher quantities of some much nastier stuff. 4 or 5 exhaust components were measured.

dave

irondave@bellsouth.net

Dave,

The link below is for DLM, SLM's successor steam locomotive company. If you click on "modern steam", then "exhaust analysis" you can see a graph of their comparsion data between a diesel and one of their 1992-built steamers burning very similar heating oil.

The steamer makes less carbon monoxide and dramatically less oxides of nitrogen (a component of smog). The steamer makes a little more SO2 and it also emits more CO2 (not shown). Basically, the steamer burns the fuel much more cleanly, but it has to burn about twice as much due to it's lower efficiency (which is about 12% for these steamers IIRC). The amount CO2, which is purely a result of how much fuel is burned, therefore goes up.

In his later years Porta became a big proponent of burning "biomass" in steam locomotives: wood, baggasse, wood chips, etc. The advantage of these fuels is that they are renewable, and the theory is that they add no overall CO2 to the atmosphere. The idea is that plant material grows and uses CO2 until either dies and decomposes giving off CO2 or can be burned and gives off the same quantity of CO2. Hopefully this CO2 is later taken in by other plants and back out of the atmosphere. Fossil fuels like coal and oil add to the CO2 in the atmosphere by releasing "new" CO2 (or at least CO2 that had previously been tied up for a very long time).

Good Steaming,
Hugh Odom
The Ultimate Steam Page
http://www.trainweb.org/tusp

> I wish I could put my hands on the sales
> literature I got from SLM showing how their
> new generation of steam locomotives (late
> 1990's) polluted less than currently
> operating diesels using their light oil
> firing system etc. I believe steam put out
> higher quantities of something relatively
> innocous but diesels put out higher
> quantities of some much nastier stuff. 4 or
> 5 exhaust components were measured.

> dave


DLM
whodom2001@yahoo.com

I think suggesting bringing steam back in the United States in regular (revenue) service operation is a ludricrous suggestion.
Coal power plants which have machinery which is much more effecient, are coming under ever increasing scrutiny from environmentalist and just general public pressure.

On the other hand though, I think there is a lot of merit to Porta's research, etc. I don't think new locomotives will be constructed using the system, but I think as time goes on, when historic coal burning locomotives require new boilers , I think this would be a good test bed for the system in the U.S., serving to keep historic engines operating.

I think someone's point about oxides of nitrogen is well taken. Increased carbon dioxide omissions could potentially be absorbed by the ocean or by trees and other plant life which use carbon dioxide. The oxides of nitrogen are not absorbed by plants in large amounts and that's why air pollution laws want to limit their emissions.

Other factors in the viability of steam in any given situation include fuel costs and often the potential risk of fire danger. In some cases a steam locomotive's low thermal effeciency could perhaps be offset by lower fuel costs. The fire danger sitaution would be helped by Mr. Porta's system as would fuel effeciency. The system also in thoery holds the fire box at a more constant temperature which would lessen wear on boiler components due to thermal expansion and contraction. I think it would be interesting to fit a historic engine in need of a new boiler with the system simply to see if it had any significant effect on the costs involved with its operation.

Regards,
Trevor Hartford

P2c3689@aol.com