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Pollution on UK newest trains

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coppercapped

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A couple of observations...

Only the very recent diesel rail vehicles meet the exhaust emissions requirements of the Euro V (Off-road vehicles) standard. Therefore it is hardly surprising that places like Salisbury and New Street (to take two examples at random) reek a bit when Class 158s or Voyagers are around. This generalisation can be extended to cover the bulk of the UK diesel rolling stock fleet.

That traces of exhaust gases make their way into the interior of rail vehicles is hardly unexpected since, unlike road vehicles (except in heavy traffic) with the exhaust at the rear, the exhaust of the vehicle in front can't be more than 20-odd meters away from the air intake of the following vehicle. In general rail vehicles exhaust at roof level for obvious reasons and air intakes also tend, at least these days, to be on the roof. The HST intakes were under the sole bar which avoided the exhaust ingestion issue — but then people bitched about the smell of the brakes. :):'(

Older vehicles, such as the Modernisation Plan DMUs and locomotives, had fuel injection systems that were nowhere near as effective in metering fuel to the cylinders as more modern ones. Coupled with opening drop-lights to every door it is clear that the exhaust will get inside. Today that may be seen as unacceptable - but, believe me, it was a lot, lot better than being continually bombarded with smuts and smoke from steam locomotives.

Don't make the common mistake of judging the past with todays standards and preconceptions.
 
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gallafent

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Don't make the common mistake of judging the past with todays standards and preconceptions.
I absolutely agree with this sentiment, but I think the start of the discussion was about judging the present in that way, inasmuchas the trains which have been found to have high levels of pollution in the cabin are the brand new 80x variants … and as you say, this is a much more serious problem than just how thick the air was when a couple of cold 15-year-old Valentas were started up on a cold morning at Swansea. Clearly a polluted environment in older trains which are still running now is also a big problem that needs to be addressed (at least for any trains that are not expected to be retired in the short term).
 

RAGNARØKR

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Hmm, if only we had some way of powering trains that didn’t involve diesel…
Burn the fuel in a steam locomotive. Have a look at the web site of dlm-ag.ch.

Efficiency is lower but in practice in service on the Swiss mountain railways it was found that less fuel is used in the steam locomotives built in 1993 than in the diesels, and there a no particulates or NOx or CO emissions. It would be worth setting up a 2-6-4 tank loco with the oil combustion and water treatment system as a comparison with battery and hydrogen techologies.

A couple of observations...

Only the very recent diesel rail vehicles meet the exhaust emissions requirements of the Euro V (Off-road vehicles) standard. Therefore it is hardly surprising that places like Salisbury and New Street (to take two examples at random) reek a bit when Class 158s or Voyagers are around. This generalisation can be extended to cover the bulk of the UK diesel rolling stock fleet.

That traces of exhaust gases make their way into the interior of rail vehicles is hardly unexpected since, unlike road vehicles (except in heavy traffic) with the exhaust at the rear, the exhaust of the vehicle in front can't be more than 20-odd meters away from the air intake of the following vehicle. In general rail vehicles exhaust at roof level for obvious reasons and air intakes also tend, at least these days, to be on the roof. The HST intakes were under the sole bar which avoided the exhaust ingestion issue — but then people bitched about the smell of the brakes. :):'(

Older vehicles, such as the Modernisation Plan DMUs and locomotives, had fuel injection systems that were nowhere near as effective in metering fuel to the cylinders as more modern ones. Coupled with opening drop-lights to every door it is clear that the exhaust will get inside. Today that may be seen as unacceptable - but, believe me, it was a lot, lot better than being continually bombarded with smuts and smoke from steam locomotives.

Don't make the common mistake of judging the past with todays standards and preconceptions.

Air quality in trains and stations deteriorated markedly when diesels replaced steam, unless they were burning filthy coal like the stuff that came from the Kent collieries. King's Cross smelt of sulphur dioxide. Welsh coal made Paddington smell not unlike a church after a round with the incense.
 

Pigeon

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Burn the fuel in a steam locomotive. Have a look at the web site of dlm-ag.ch.

Efficiency is lower but in practice in service on the Swiss mountain railways it was found that less fuel is used in the steam locomotives built in 1993 than in the diesels, and there a no particulates or NOx or CO emissions. It would be worth setting up a 2-6-4 tank loco with the oil combustion and water treatment system as a comparison with battery and hydrogen techologies.

Maybe I didn't find it but I didn't see anything particularly novel or impressive on that site. Lot of stuff about how fireless locomotives make a lot of sense for shunting the yards of works that necessarily have huge fixed boilers anyway; well, duh, but on the other hand how many such works are there left these days? They don't seem to acknowledge that we should be getting rid of all the combustion-powered steam-turbine-based power stations and building nuclear ones to compensate for the failings of renewables, and therefore they are chasing a disappearing use case (maybe they are confused by the Germans getting that one arse about face).

Nor do they seem to acknowledge any means of increasing the range of fireless locomotives other than simply increasing the pressure, for instance using the heat of solution of sodium hydroxide, which AFAIAA is about the only one that has been demonstrated in practice to (a) work, over a useful range, and (b) not be more hassle than it's worth.

In any case, dealing with all the safety doings around mobile steam pressure vessels - even if they are only tanks and not boilers - is something few people are going to want to get into if they don't have to; indeed that is a lot of the reason for developing various alternatives to steam in the first place, and they are now good enough that if you are not one of the handful of people needing to shunt the yard of a coal power plant, and maybe even if you are, you'd never choose anything else.

There was an interesting mention of a yard being shunted in a four-hour operation by a Class 66, during which it naturally spent most of its time on idle, and consumed 640kWh in the energy content of its fuel. (They then use that figure as a basis for an "efficiency calculation", which isn't really particularly meaningful in the context and is more sensationalism than engineering.) What is particularly interesting is that they reckon the work output in shunting was only 10kWh. Not sure how they actually got that; it's a bit on the low side for force x distance at the drawbar, but not totally unfeasible; but if it's even only half way accurate, to me it argues not that one or two people ought to think about fireless locomotives, but that an awful lot of people should jump at the chance to shunt their yards with a battery-electric locomotive: if that's all the energy you need, you could power it from a Nissan Leaf battery and still have some left over to run the driver's cab heater in the winter.

Oil firing of steam locomotives is of course a very old idea, and it's a bit of a stretch to claim it as having solved the pollution problem. To be sure it doesn't require much skill from the fireman to avoid a claggy exhaust, but it still produces lots of carbon dioxide. They're not so much "solving" anything as promoting a method by which one aspect can in certain circumstances be sidestepped.

Didn't see anything about water treatment. I'm not sure what the Festiniog do for that, but they have used oil firing for a long time, and AFAIK they still find steam locomotives use a lot more fuel than diesels.

Water treatment seems to be a bit of an underappreciated factor, and I get the impression that a lot of people are still using various traditional witches' brews rather than something scientific like the Porta system. (Something about Porta treatment being applied to 6024 in the manner of a novel experiment rather than simply an extension of established practice.) A major cause of inefficiency in a steam locomotive is the amount of heat you fail to transfer to the water from the combustion gases before they get to the smokebox, and the treatment not only needs to prevent the accumulation of insulating scale, but also to lower the surface energy at the water/tube interface so the water "wets" the tubes better and collects the heat more effectively. (That latter factor is similarly important in the witches' brews vs. scientific formulation question as applied to coolant additives for diesel engines.) Changing to Porta treatment may be a bit more hassle, but it is definitely worth it.

The Porta system also addresses the problem of the mucky exhaust, by restricting the air supply underneath the grate while increasing that above, and injecting steam into the firebed, to oxidise the coal in a two-stage process, first with water in a producer-gas reaction and then with atmospheric oxygen combining with the resulting gases. Because the combustion air is now supplied above the firebed with only a minimal amount passing through it, you avoid the problem of entrainment of unburnt coal particles and ash. As well as giving a clean-looking exhaust, it allows you to burn slack, and extends the range of usable fuels in general, rather than restricting you to one particular type as oil firing does. Still produces loads of carbon dioxide, though...
 

RAGNARØKR

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Thanks for reply.

The innovations are the use of light oil, pre-heating systems, water treatment (extreme high pH) and improved exhaust arrangements. The problem of pollution in stations and trains is resolved (diagram), this was the subject of this thread. That at least should put steam in the running alongside battery and hydrogen technologies and it ought at least to be evaluated; the cost will be a fraction of the amounts being put into experiments with hydrogen. A trial unit will readily find an after-use on one of the preserved lines, and will no doubt be of interest given the pressure to get rid of coal, the shortage of volunteers and the need to reduce wear and tear on valuable museum pieces.

A modern oil firing system is used on the steamers in the Stockholm archipelago which are in service during the summer together with modern vessels; they give a cleaner exhaust than the diesels, and a smoother and quieter passenger environment.

The principal inefficiency of steam locomotives is thermodynamic, due to the relatively low temperature of the steam compared to the hot gas in an internal combustion energy, also the fact that the engines do not condense the steam. Higher superheat is made possible by improved lubrication, and improved exhaust systems have pushed up the efficiency somewhat, from about 8% to a claimed 12% - not wonderful but worthwhile. There is obviously energy going to waste in the barking exhaust of GWR engines, compared to the soft exhausts of Bulleid locomotives. Secondary inefficiencies are due to the loss of heat not transferred in the boiler, as you say, as well as heat loss through poor insulation and leaks. There is no excuse for treating water with witches' brews not based on sound chemistry. Steam has compensating efficiency advantages due to direct drive and the low standby/idling losses achieved with oil firing.

All traction systems need to be assessed in relation to their whole-life environmental costs from mine to scrapyard and recycling plant, including embodied energy in structures and vehicles. I get the impression that many of these costs are being ignored by the promoters of alternative and allegedly green energy.

In the 1990s DLM was originally SLM and part of Sulzer. The project began when the need to replace the 90 year old locomotives on the tourist railways became apparent. The enthusiasm for fireless locomotives is that there were a lot of them left over in Eastern Europe from the Communist period, which could be put back into use. The diagram was in a more detailed technical paper which seems no longer to be on the site.

At the Swiss mountain railways it was discovered, surprisingly, that the new steam locomotives were not consuming as much fuel oil as expected, which led to the manufacturer (who didn't expect it either) coming back to do an energy audit.
 

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coppercapped

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I absolutely agree with this sentiment, but I think the start of the discussion was about judging the present in that way, inasmuchas the trains which have been found to have high levels of pollution in the cabin are the brand new 80x variants … and as you say, this is a much more serious problem than just how thick the air was when a couple of cold 15-year-old Valentas were started up on a cold morning at Swansea. Clearly a polluted environment in older trains which are still running now is also a big problem that needs to be addressed (at least for any trains that are not expected to be retired in the short term).
I take your point about the reported situation with regard to the Class 800s. But I would disagree about the seriousness of the 'problem'.

However…
…and there always is a ‘however’(!)… the Guardian article by itself is not very clear.

It is only recently that measurement equipment for detecting particulates, various nitrogen oxides and other pollutants has become portable enough and cheap enough for such measurements to be easily made in trains, buses, cars and the like. So it is hardly surprising that people are making measurements at times and in places that previously were not possible and publishing the results. My old physics professor used to say that one measurement was no measurement and that two measurements were effectively only one measurement. Conclusions can only be drawn after a series of measurements and then only after taking into account sources of errors and allowing for them.

So, were the results reported for the Hitachi trains taken from one journey, or were they an average taken over many journeys? Were the weather conditions the same? Rain or wind direction can affect air flows and exhaust flows and air temperature can affect combustion conditions in the engine.

Only after all these factors have been taken into consideration can any conclusions be reached. One of these is that it may be necessary to re-examine the workings of the exhaust gas treatment system or the positioning of the air conditioning intakes or air treatment equipment. On the other hand any long term health effects are strongly influenced not only by concentrations of noxious substances but also by length of time of exposure, so any side effects of a train journey lasting, at a maximum, of only a few hours will not be noticeable by any individual. It may be that significant sums of money can be spent simply to satisfy newspapers with no noticeable improvement in the longevity of the passengers.

Were any measurements taken inside HSTs to give a comparison? It may well be that NOx and particulate levels within the train were higher in days gone by - certainly in the latter days of the Valentas - and the 800 trains are an improvement. In which case the published results should result in the trains being praised rather than being presented in a way that implies that the railways are trying to kill their passengers.

I entirely support #pigeon’s post #71 in this matter. And I would again emphasise that people seriously misunderstand the statistics concerning the links between premature deaths and various forms of pollution. Essentially the statistics show that if you have lived for a large proportion of your life near a source of pollution - downwind of a noxious chemical plant for example - then statistically one can expect to die a few months earlier than the actuaries would predict. In other words the effects of very long term exposure to pollutants mean that at the age of, say, 87 you might die in June instead of November.

Such events can only be determined statistically, not individually. Any other interpretation is scaremongering.
 

Trainbike46

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So, were the results reported for the Hitachi trains taken from one journey, or were they an average taken over many journeys? Were the weather conditions the same? Rain or wind direction can affect air flows and exhaust flows and air temperature can affect combustion conditions in the engine.
Most of the questions you ask are answered in the RSSB report (available here: https://www.rssb.co.uk/research-catalogue/CatalogueItem/T1188 ). In short, the guardian reported the highest measured levels, EMR HSTs were also included, as were other trains such as 755s and 230s. There were multiple journeys included, but fewer than originally planned due to covid. They also did comparisons to other transport options, such as cycling and driving, as well as looking at the impacts of tunnels on measured levels.

To me, it sounds like there is not much to worry about, but it does offer further support for electrification of the rail network (on top of the operational and climate change benefits!)

I'd really recommend having a look at the RSSB report, because it's much more helpful than the guardian article.
 

coppercapped

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Most of the questions you ask are answered in the RSSB report (available here: https://www.rssb.co.uk/research-catalogue/CatalogueItem/T1188 ). In short, the guardian reported the highest measured levels, EMR HSTs were also included, as were other trains such as 755s and 230s. There were multiple journeys included, but fewer than originally planned due to covid. They also did comparisons to other transport options, such as cycling and driving, as well as looking at the impacts of tunnels on measured levels.

To me, it sounds like there is not much to worry about, but it does offer further support for electrification of the rail network (on top of the operational and climate change benefits!)

I'd really recommend having a look at the RSSB report, because it's much more helpful than the guardian article.
Is the report open to everybody? Or only rail employees? The link shows me that I have to register and asks about my company. As I am retired, that's difficult...!
 

Trainbike46

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Is the report open to everybody? Or only rail employees? The link shows me that I have to register and asks about my company. As I am retired, that's difficult...!
You do need an account, but I think it's open to everyone? I filled in my university as employer (which is accurate, as I do work for them), and I suspect the system will still give you access if you just fill in 'retired' as employer? Definitely worth a shot!
 

Irascible

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Basic RSSB membership is open to anyone as far as I know. I registered years ago as a contractor to a company writing training & advertising product, which is about as remote as you can get, but I doubt I'd have needed the company connection.

They don't seem to acknowledge that we should be getting rid of all the combustion-powered steam-turbine-based power stations and building nuclear ones to compensate for the failings of renewables, and therefore they are chasing a disappearing use case (maybe they are confused by the Germans getting that one arse about face).

Nuclear power stations are of course still steam-turbine-based power stations. Whether a) they need shunting engines & what they do with them and b) it'd be better to steam power them or battery power ( fireless steam is certainly a simpler device ) is a different discussion... I don't know enough about nuclear power stations to know the answer to a, but I guess b is a bit dependent on a. I don't know enough about safety cases to know whether the case for a large rack of batteries is better or worse than a boiler full of HP steam either, that seems an interesting one.
 

jfollows

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You do need an account, but I think it's open to everyone? I filled in my university as employer (which is accurate, as I do work for them), and I suspect the system will still give you access if you just fill in 'retired' as employer? Definitely worth a shot!
Good point, thank you, and I can confirm that "retired", "retired" and "Other" in various fields work fine, and I've been able to register and download the report.
 

Pigeon

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Nuclear power stations are of course still steam-turbine-based power stations. Whether a) they need shunting engines & what they do with them and b) it'd be better to steam power them or battery power ( fireless steam is certainly a simpler device ) is a different discussion... I don't know enough about nuclear power stations to know the answer to a, but I guess b is a bit dependent on a. I don't know enough about safety cases to know whether the case for a large rack of batteries is better or worse than a boiler full of HP steam either, that seems an interesting one.

I guess they have some need for internal shunting of flask trains, at least.

Safety of batteries... depends a lot whether or not you're using fancy expensive lithium batteries with their tendency to self-ignite and release clouds of hideously nasty chemicals like HF both in the combustion and in the attempts to put them out (which fail). (Official advice from Tesla is "use loads of water on it and all the HF doesn't matter, it's only HF".) Even so, people seem remarkably unconcerned about letting them run around on the road in uncontrolled numbers without needing to re-certify their fireproofness every 10 years.

For a battery shunter, the characteristics of light weight, high energy density, and ability to accept charge as fast as they can put it out, which are so important in electric cars, are much less critical, and the choice of the far more benign good old lead-acid battery is a lot more attractive. You are not short of space to put a big enough battery for the range you need, the same range is five times cheaper, and the weight is probably an advantage as you don't need additional ballast to support the tractive effort. Environmentally, they are probably much of a muchness: people hate lead these days, but lead-acid batteries are extremely recycleable, especially in an industrial setting, and release very little, while lithium batteries require a lot of ill-regulated mining for uncommon and toxic ingredients with all the associated mucky waste. NiFe cells may be an even better option (cf. LU battery locomotives).
 
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