Are diesel’s days numbered? A view from a trip to BYD’s electric bus factory
arstechnica.com
arstechnica.com
• The front destination signs seem to always have had problems. In addition to the technical problem (that is, problems with the signs themselves), there is also a weird build issue on some of the busses: The bus has a front panel above the windshield, part of which (the part in front of the sign) is transparent. For some reason, some buses got an unusually-small transparent area, with a regular-size sign display, which meant that the test was always partially-unreadable. I assume that different display hardware was supposed to be used?
• The acceleration and braking dynamics are _very_ different compared to diesel (and even diesel-hybrid) busses: Because so much torque is available immediately when moving from a stop, it is very easy to jerk passengers around. Similarly, the busses like to move into regenerative braking immediately the foot is lifted off of the accelerator, often making another jerk. It can be difficult to adjust (as a driver) if you're moving between multiple different types of busses, during a week or even during a shift.
Both of the above issues are things that can be rectified, although I wonder how much modification would be needed to get smoother acceleration and braking. And regardless, the time needed for the bus to be out of service (to implement any necessary modifications) is still time where the bus's value is continuing to depreciate.
I think the biggest plus point is, if you are seated, and facing in the direction of travel, then the acceleration/deceleration issue doesn't apply. You then have an experience where you get to where you need to go much faster, because the bus is better able to keep up with traffic.
Also, regarding two of your points:
> I imagine they are very quiet…
Actually, the answer may surprise you! My experience has been that the electric buses can be louder than their diesel equivalents. I expect this is because that, for diesel buses, the noisiest components are all in one place (normally the very back of the bus) with soundproofing material in place between the engine compartment and you). Electric busses (at least the ones I've experienced) have motors spread all around you, with less sound-dampening material in the way.
> …and don't smell like exhaust.
Exhaust smell is not something I've particularly noticed from the remaining diesel busses. I expect that is due to three reasons: (1) The emissions standards placed on California-registered diesel vehicles; (2) the maintenance regime in place; (3) the fact that, when I leave the bus, I end up going towards the front (and away from the exhaust pipe). Although, in places that I've experienced which don't have (1) and (2), you are right!
And when commuting on a bicycle, not having to stand in traffic behind a diesel bus is a welcome relief. Possibly life changing to some degree. The fumes from old buses are absolutely disgusting.
Like a lot of things this will depend on the make and model. In San Francisco, Muni bought a bunch of Skoda electric trolleys in the early 2000s. They were extremely loud compared to their predecessors and their replacements.
Muni also bought some Cummins powered diesel buses around the same time. Those too were extremely loud (roughly 90 dB at not-so-far-away distances), but 90 dB was loud enough to gain some traction with Cummins and Neoplan. Still, these buses were far less grating to me than the old two-stroke diesels (it's a beautiful whine from a mechanical standpoint, but not something I want to hear a few times an hour driving past my house).
> Exhaust smell is not something I've particularly noticed from the remaining diesel busses.
California is well off in this regard, I can't remember seeing more than one or two trucks belching smoke. Even in Europe I don't remember the interior of the buses smelling much of diesel exhaust -- and they shouldn't, you really don't want to expose your passengers to exhaust fumes.
Cuba was an interesting contrast as they burn some of the lowest grade diesel fuel around (and most things are diesel these days). The smell of high sulfur diesel is unlike anything I've smelled before.
Then again, the "gas pedal" is basically a skeuomorphism dating back to when it mechanically opened up a gas valve... it's all drive by wire, so, "fix it in software"?
Drove a Volkswagen E-Up. It had an Eco and an Eco+ Mode. Those seemed to just limit the acceleration, and for a bus this seems mandatory.
Of course the engineers who design eco mode probably know more about how to do this than I do. I know they mess with shift points, it wouldn't surprise me if they did other things too.
Some EVs have a transmission - while it isn't strictly required (which is why others do not) for best acceleration you need one. If there is a transmission this is a shift point.
Of course EVs have completely different operating parameters. The rest of my post was respect to a internal combustion engine.
But what they don't generally have, unless they are conversions from ICE cars, is changing gear ratios. Torque is mostly constant across all RPMs in an EV, so there's not really a need for one.
I'm used to seeing the tail bus-number screens being dead more often than not, although I can't say if that's our new Novabuses or not.
And these vehicles are priced into the high six figures.
So I'm not surprised that electrics have a similar disinterest in passenger comfort when it comes to the typically-strong acceleration and breaking of electric vehicles.
I imagine it's a dogfood situation - the users aren't the ones making the buying decisions.
>Both of the above issues are things that can be rectified, although I wonder how much modification would be needed to get smoother acceleration and braking. And regardless, the time needed for the bus to be out of service (to implement any necessary modifications) is still time where the bus's value is continuing to depreciate.
This is just a teething issue. City buses are geared to top out at low highway speeds, like 50-65mph. Current diesel drive-trains have more than enough go power to send passengers flying but they don't because they're mature technology. Pretty soon they'll figure out how to put the power down in a way that doesn't toss people around.
Electric buses are hardly new or immature technology. The batteries are new, sure, but the motors and their control bits are not. Some vehicles are going to be easier to drive smoothly than others. Take a look at the Van Hool (diesel) buses that Alameda County and Washington DC bought, there are plenty of complaints about how they're jerky by design.
source: i develop software for buses.
Decoration signs/asthetics - Poor client requirement. It isn't hard to say how large a display should be and cut the shape. I found the design of the front windshield interesting. Very curved, looks oldskool. Cute. Traffic in Chinese cities is pretty start-stop, with buses kings of the road. No one will try to cut-off a bus. You're right there's a lot of torque.
Drivers should not be switching type of bus more than once ever (per change in model). Lines replaced here are replaced overnight: all buses serving the route yesterday replaced with new buses today. The drivers do need time to get used to the new power supply, and also the new balance of weight bus bus now has (diesel and wheel-base applicable too).
When passengers and driver have gotten used to it, the ride is very smooth.
For charging: Peak time is rush hour. Buses going about 150km perhaps over 4ish hour time slots (urban). During the day they charge (relay team, one takes on lower frequency scheduling while the other charges, on destination another goes off-charge while the returning bus charges). When all on a full-charge and in evening rush-hour 3-4 hours everything is sweet.
Charging and usage-patterns shouldn't be a problem for a bus.
Pretty neat, especially considering that nickel and iron are extracted in nearby Russia and are much cheaper than lithium.
Interesting for this one it says: buses will be equipped with Chinese supercondensers that proved to operate very well in Bulgaria and China. Re-charging will not take more than 7 minutes.
[1] https://www.e-education.psu.edu/fsc432/content/overview-refi...
About that:
https://electrek.co/2018/02/03/all-electric-ferry-cuts-emiss...
The title is (of course) fairly misleading - while we've got electric boats and semis it is unlikely that long haul transport for either will be electric any time soon. But - at least they are away from urban areas, for the most part.
The latest EU diesel standards for passenger cars are actually on par with the gasoline standards. Don't know what the standards are for heavy trucks though.
Can we trust any of the big automotive manufacturers to actually meet those standards without cheating?
Look at how widespread the issue is [Dieselgate](https://www.cleanenergywire.org/factsheets/dieselgate-timeli...)
https://www.forbes.com/sites/davekeating/2018/07/26/carmaker...
> The automotive industry says it has cleaned up its act. But this week the European Union’s executive branch, the European Commission, revealed it has discovered a whole new form of cheating – this time on CO2 emission tests. The 2016 scandal concerned air pollution tests on diesel vehicles, where automakers were using so-called ‘defeat devices’ during tests to make the cars seem like they were emitting less pollution. Now, the carmakers are accused of doing the opposite – artificially inflating the level of carbon emissions produced by new cars coming onto the market now. Why would automakers want their cars to look more emissions-intensive than they are? Because a new EU law will require automakers to reduce their fleet average CO2 emissions by 15% by 2025 and 30% by 2030 – based on 2021 levels.
I know this is anecdata, but at least in CO, UT, WY area there are more modified trucks than what is immediately apparent, since often a truck w/ bypassed emissions equipment isn't heavily cosmetically modified.
And, I'm sad to say, some folks just like the whole "rolling coal" thing and the ability to put out huge plumes of black smoke.
There are a fair amount of people who will actively pollute because you asked/told them not to, and I wonder if they have a significant effect on the environment
Changing that production mix is capital-intensive, but everything in the petrochemical business is capital-intensive. US refineries are having to substantially change their operations because of the increasing production of unconventional oil, which yields a very different mix of distillates compared to conventional crude.
https://en.wikipedia.org/wiki/Fluid_catalytic_cracking
https://pubs.rsc.org/en/content/articlehtml/2015/cs/c5cs0037...
It doesn't combat overall pollution, but it does improve the quality of life for people living in urban areas.
From your own citation:
"Separation processes, such as distillation, dewaxing, and deasphalting make use of the differences in the physical properties of crude oil components to separate groups of hydrocarbon compounds or inorganic impurities, whereas conversion processes cause chemical changes in the hydrocarbon composition of crude oils. For example, Fluid Catalytic Cracking process breaks chemical bonds in long-chain alkanes to produce shorter chain alkanes to produce gasoline from higher boiling gas oil fractions"
This is fud.
The point of electrification is to get a path towards sustainability. If it means demand for barrels of oil decreases, or in the most extreme, all that extra diesel becomes a stranded asset, all the better (unless you're a refinery owner).
Also, diesel engines can be converted to DME which is cleaner and offers a path for CO2 recycling. DME/electric plug-in hybrids is a solution mainly for trucks and shipping because they can automatically switch to electric near populated areas and use the ICE for extensive range.
Long term goal is of course to not extract oil at all, but some products will be hard to replace without radical new technologies.
-- Diesel locomotives (train engines) and many ships use diesel generators to power electric motors -- this setup is useful for applications where high torque is required at low RPMs (even down to 0 RPM)
-- Many grid support power plants use diesel generators (especially for emergency backup)
-- Diesel-powered trucks, tractors, and heavy equipment
-- Military vehicles
/s
Run the numbers noting that all these have much lower power to weight ratio's than buses and cars.
Numbers say diesel is more expensive on a total cost of ownership basis.
Few ships are diesel electric. It's inherently fairly inefficient compared to mechanical power transmission. Diesel electric is mostly used in locomotives and heavy mining equipment where a mechanical drive-train would be overly complex or inconvenient to package (imagine the drive-train for a freight locomotive) but the machine enough driving that hydraulics is too inefficient (whereas something like a mining shovel doesn't do much driving and the market).
>Diesel-powered trucks, tractors, and heavy equipment
For stuff that's small enough to transport on a semi and doesn't need to go highway speed it's really hard to beat hydraulics for low cost and low cost of ownership. A slightly more efficient drive-train doesn't really make it far up the important features list when you're gonna be pushing dirt and your maintenance schedule and how hard on equipment your employees are dominates your longer term cost of ownership. Indoor stuff will go more electric but it's been electric for awhile, it'll just get better/lighter.
>Military vehicles
Not gonna happen anytime soon except some specialty applications (small inshore subs come to mind, SDVs are already electric). Military stuff needs to stay light for a variety of reasons and the last thing they need are a bunch of volatile batteries that need to be protected (whereas a fuel tank of diesel can act like armor to some extent).
Can you provide a source for this? It has been my understanding that turbines had more of an infra-red signature due to the hot exhaust and high mass flow.
I do not have references. I learned it from a buddy whom I trust.
But one of the advantages of Diesel engines are that they aren't really that picky when it comes to fuel. I don't think the engines are going anywhere, but we're probably going to see more and more non-fossil Diesel alternatives being used in the future.
What a great market that would be for Waymo. Predictable routes of mostly highway driving would be right up their alley.
Seattle used to run dual gas/electric (not really hybrids since no battery) in the downtown tunnel by having them attach going in and Unattach going out. Great when it worked, but it often didn’t, so they just use cleaner emission buses now instead.
Some companies might have autonomous tech that's a good match for those constraints, despite the much smaller market.
One thing I think most people don't appreciate is that the switch to self-driving cars will transform America into a mostly-transit society. Once you don't need a car to live from day to day, you sell it. Then you take a self-driving Lyft from your house to the bus depot, train station, or airport.
The market for self-driving busses between cities will grow alongside the market for self-driving cars within cities.
If self-driving taxis are ubiquitous enough, there could be very little wait time between hailing a taxi from an app on your smartphone and the taxi arriving at your location.
At some price point, it will stop making sense to spend $20,000-$30,000 to buy a car. And you won't have to pay for insurance or gas or wear-and-tear or parking. The car could be out making money instead of being parked 22 hours a day.
Businesses and apartments and home developers will stop building parking spaces and parking lots once self-driving taxis hit a sufficient threshold.
Finally, cars will solve transit's "last mile" problem. Instead of paying for a taxi from home to work, you can pay for a taxi from home to the Light Rail station.
plus it would get kid used to the idea of an EV world and not having to sit on buses idling for too long
[1] http://www.latimes.com/local/lanow/la-me-electric-buses-2018...
Just because America cannot make something work, doesn't mean it cannot work in other countries. Especially in the public sector context, which is full of mismanagement in America.
I expect this electric vehicle maker will get their act together with time!
Also, the article seems to acknowledge that city driving is the best application for electric vehicles.
For comparison, Paris (I should say the Parisian region) plans to have only 2,000 zero missions buses by 2025! And that official numbers includes NGV... So much talk about the transition (remember the "Paris Agreement"?) and yet, so little progress...
https://en.wikipedia.org/wiki/General_Motors_streetcar_consp...
However, as batteries have gotten far better, now batteries are starting to rival oil as an energy source on its parameters and economics.
City driving is indeed the best environment for EVs simply for the air pollution reasons, never mind the added benefits of lower speeds and lower ranges.
It seems especially silly to order a custom looking bus because this would obviously raise the price of replacement parts. Is this part of why old buses always look like crap? Cities don't want to pay the crazy cost of replacing a custom part that is clearly damaged or worn out.
Green tech is a universal political point in Europe, at least north, Western Europe, and car companies aren’t stupid. It takes time to alter production, but they are getting there, as demands keep increasing.
In Norway half the cars sold are electric. I personally own a petrol car, but I doubt I’ll replace it with a fossil.
More interesting is the Aptis by Alstom, still more or less a prototype but its design is really something innovative because it increases the room in the bus and it is 100% low floor.
The situation has decayed to the point that Albuquerque has considered trying to terminate the contract. The first several units delivered have had significant quality problems, and recently the city's inspector general released a report suggesting that audits showing the buses comply with Buy America regulations were falsified and they are potentially ineligible for expected federal grants. Workers in the city transportation department have voiced concerns about many of the components on the buses being apparently manufactured in China and lacking US certification marks and, in some cases, English documentation. Delivery on the remaining buses in the order continues to move farther back.
The City went into the project understanding that the 60-foot buses were a new product for BYD, and even expects federal funding from a grant program for employing new technologies. But at this point BYD is a significant part of the near complete failure of a major project built around their product. It seems worth mentioning that their customers are not all happy.
To ART's credit, the city IG reports that massive pressure for the city forced BYD to begin delivering units earlier than they otherwise would have (but still significantly behind schedule).
https://www.abqjournal.com/1116887/mayor-outlines-major-prob... https://www.abqjournal.com/1182473/report-criticizes-art-pro... https://www.abqjournal.com/1182905/report-company-sent-fault...
Part of the grant program the city is using to fund the project is that the city will send one or two units to an FTA facility for inspection and testing. That testing is expected to result in the FTA certifying the model for future non-experimental federal grant programs, but most people involved in the ART project now have significant doubts about whether or not BYD will be able to deliver units that pass this process.
In London we've had a few BYD busses in London since late 2016 now: https://tfl.gov.uk/info-for/media/press-releases/2016/septem...
This appears to be the bus they use: https://en.wikipedia.org/wiki/BYD_K9
I'd love to know how they are holding up (I have to assume that the limited deployment is effectively a trial by Transport for London to see how well they work) if anyone knows of any updates on those?
Based on the statistics for London buses (about 490 million KM driven a year by 9616 buses = about 51,000KM a year, or about 32,000 miles a year source: https://tfl.gov.uk/corporate/publications-and-reports/buses-... for distance and https://data.london.gov.uk/dataset/number-buses-type-bus-lon... for number of buses) it would seem that the average daily distance for a bus would likely be somewhere in the 80-120 miles a day range depending on how many days a year a bus is driven (that range is for 365 days to 250 days a year). At 80-125 miles a day, that seems like it is screaming out for electrification right now. It would seem that it is totally within the reach of current technology. The BYD K9 has an advertised range of 155 miles.
The sooner diesel buses (and trucks) leave urban areas like London the better. The rancid stench and taste of diesel fumes that hit you is disgusting, not to mention that some diesel vehicles are outrageously loud too. Diesel is literally killing us.
They seem to be holding up ok. They are only used on some unusually short routes.
I'm with you on the sooner the bussed go electric the better. Shenzhen has done all 16,359 of its busses so it's possible. They seem to be BYDs too. https://www.vox.com/energy-and-environment/2018/4/17/1723936...
Personally e-bus is matter of comfort and reduced noice for me and people around.
Even their desire to stick it to the techies will not overcome their love of car-first, or sometimes car-only, policies.
I was shocked to see public opinion change overnight on this issue because some German auto manufacturer cheated on their tests. This should motivate people to fight corruption, not fuels.
Properly maintained EURO4+ vehicles are just fine. Yes, they product some more particulates and NOx, but if you look up the specifics in absolute values, the difference is essentially trivial.
Replacing diesel with gasoline in commercial vehicles will increase transportation prices at least 30-40%, my guess would be much higher. It simply won't happen. Commercial electric vehicles are a dream (or a financial nightmare, depending on your perspective) at this point.
Are diesel's days limited in light personal transport vehicles? Maybe, depending on politics. Are trucks, buses etc going electric anytime soon? Not really.
For public transport, most people and most city councils will choose to improve their services (like more routes, more buses per line etc) and not to shrink just to use the latest bus-sized gadget.
Anyway, Infiniti has a new engine that is variable-compression, so they can run at 14:1 OR 8:1, and they add on a turbo to use at the lower compression. Pretty freaking sweet: https://www.infinitiusa.com/about/technology/vc-turbo-engine...
- Skyactiv uses the spark to control the compression-based ignition.
- Skyactiv-X goes a step further to use only compression to ignite 87 octane gasoline.
However, it's not all good. Apparently direct injection gasoline engines emit more particulates than conventional gasoline engines. This may be a manageable problem and new regulations are supposedly in effect from 2017 in the US (unless they got caught in Trumps emissions control rollback), but that does not clean up the several years of cars with direct injection before now.
It's nice that BYD is using lithium iron phosphate batteries. Much safer than ordinary lithium-iron batteries. You really don't want a bus-sized battery fire.
Edit: Vancouver has been running electric buses since 1948.
https://en.wikipedia.org/wiki/Trolley_buses_in_Vancouver
And these are not cable cars running tiny tourist routes in a downtown core. These buses cover the suburbs.
https://en.wikipedia.org/wiki/Trolley_buses_in_Vancouver#/me...
I think this is the only advantage combustion engines still have. It seems to be a big one. To refill a tank takes less than 10 minutes, with the range stated by parent.
SUV/Pickup rentals are often >$500/week, AND the agreement will claim that I'm not supposed to take it off road, so if I'd like to go out to some hiking trailhead along the way, I'm totally uninsured if anything happens on that dirt road.
Adding $1000 to the cost of one of my yearly vacations adds up to a lot of money over the life of a car.
--------
On that same note, long trips are quite common for many Americans who don't commute those distances. My daily commute is 4 miles each way, I could bike it if the road had better infrastructure for it.
On at least 2 weekends a month, I'm driving 200+ mi each way, and my destinations typically do not have charging infrastructure (or paved parking lots). I know lots of people who do the same for their various outdoor hobbies.
They really should. If you don't need to stop for a loo break after ~4 hours (at 75mph), you're not drinking properly. And you really should get out of your seat for 20-30 minutes after 4 hours non-stop driving.
It makes sense to use Lithium Iron batteries in a bus because these batteries can take more recharge cycles 2000-8000 instead of the normal 500 recharge cycles of Lithium Cobolt.
https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery
Would love to hear why electric buses actually have the lead over CNG if you take out the pure “feel good” factor of electric
https://bigthink.com/design-for-good/wireless-charging-road-...
But agree that hybrids seem like an interesting option. Electrifying half the route may be much much easier than electrifying 100%, and would let you run small-battery electric busses all day.
[0]https://en.wikipedia.org/wiki/BYD_Auto#Sales >BYD Auto sold a total of 506,189 passenger cars in China in 2013
[1] https://en.wikipedia.org/wiki/Proterra,_Inc. >the company has sold more than 375 buses
Thus i think the engine itself is likely to be with us for a long time, but perhaps not used primarily in the ways we do today.
https://www.reuters.com/article/us-byd-results/chinas-byd-wa...
Gasoline engines have lesser thermal efficiency and lesser torque potential than diesel engines. If you're going to get rid of one or the other, get rid of gasoline vehicles.
Diesel engines have a longer stroke, cooler combustion, more flexibility with air/fuel ratios, extreme wear tolerance, lower rotational speeds, and cost the same with similar complexity to gasoline engines. They are also more economical in practice because their extra low-end torque gives them (arguably) a drivability advantage which lends itself to increased MPG.
They are superior to gasoline engines in every way. And because they can run with air/fuel ratios anywhere from 10:1 all the way to 60:1 they can easily run a mutitude of different fuel's with only minor software adjustments.
So please, stop shitting on diesel. It's ignorant to the fact that you probably drive a gasoline powered car that does more damage to the environment per gallon of fuel burned than a diesel bus.
Diesels are only good for limited purposes, like buses and trucks, that need the higher efficiency.
sources and additional reading: https://pubs.acs.org/doi/pdf/10.1021/es034928d
https://phys.org/news/2017-05-carcinogenic-soot-particles-pe...
https://www.energy.gov/sites/prod/files/2014/03/f9/2002_deer...
Second paper only considers fine-size (<20 nm) particulates (and not larger sizes like 100nm+) of direct injection cars, and is a bit misleading by comparing six cars to a single carefully-selected diesel car with particulate filter. Further, in reality here in a London, people are cutting open their Diesel particulate filters to avoid cost of replacing clogged filters and still passing MOT exhaust tests, which apparently don’t/can’t check for filter tampering.
Third paper is way back in 2002 and considers only cars, not heavy trucks and buses, which are way worse in urban settings.
What about pollution? There is sufficient evidence that the fine particles cause cancer
[0]https://www.cancer.org/cancer/cancer-causes/diesel-exhaust-a...
Sorry to be rude but this is a very personal and emotional topic to me and you’ve really pissed me off by saying “They are superior to gasoline engines in every way.” You apparently aren’t living in a city where the poor-sighted decision was made to promote Diesel engines over gasoline for marginally better CO2 metrics, and now get to breathe air that exceeds annual EU pollution limits in mere days.
Diesel is terrible in urban settings. It’s dirty as hell. I have no idea where you live but Diesel engines are entirely on their own choking the streets of London with their particulates and NoX exhaust. Gasoline engines are much cleaner by comparison.
I’ve gotten bronchitis several times in the past few years. I’ve finally tracked it down to the nox fumes, primarily from buses and heavy trucks where it’s a very noticeable sharp smell. I’ve gotten a bit better by avoiding high streets whenever possible, and I’m also proactively going up to drivers in idling diesel cars and asking them to cut the engine. It’s been estimated that 10k people are dying a year in London alone from effects of the exhaust!!
Oh, I'd really love to hear how you did that.
The tricky part is that there’s usually a delay of a few hours between exposure and cough attack. Intentionally avoiding high streets has helped for me. I still get coughing fits but not as many full on cases.
So to limit particulates, add a throttle limiter that limits throttle changes to a certain speed where the temperature of combustion increases proportionate to the fuel being injected.
You can also reduce soot output by filtering the fuel. You can refine diesel until you're blue in the face, but the fact of the matter is you get to a point where the cost of refining it isn't worth the benefit coming out of the tail pipe.
Not to mention the soot falls back to Earth and doesn't stay in the atmosphere as long as you think it does. So much of that black cloud is getting washed into your sewers when it rains.
You've found a bug in your code and you want to throw it all out and start over?
Though you appear to have some vested interest in the proliferation of Diesel engines.
I owned a 1990 CTD Dodge W350 truck and that thing would do a brakestand from a 3rd gear clutch drop AT IDLE... with 300k miles on the clock. Find me a V8 gasser that can do that and pull a trailer through the Kangamangus at 20+mpg.
2) references please (for you arguments)
The more common solution it diesel particulate filters in-line of the exhaust pipe that cause the soot to completely burn off. This is a trade-off because the DPF requires maintenance. Some systems even go so far as to implement aggressive exhaust gas recycling, pumping already burned exhaust back into the intake to be burned again.
And for references... 1. Why do diesels produce black smoke..... https://commercial.lubrizoladditives360.com/black-smoke-caus...
2. What is diesel exhaust..... https://en.wikipedia.org/wiki/Diesel_exhaust
3. Diesel misconceptions..... https://phys.org/news/2011-06-myths-diesel.html
We're really having this conversation about combustion. For city driving of all types, it's time is very nearly up.