
The Dirty Truth About 'Clean Diesel' - kdazzle
http://www.nytimes.com/2016/01/03/opinion/sunday/the-dirty-truth-about-clean-diesel.html
======
mschuster91
Why does everyone concentrate on fucking cars? Cars are not the problem, the
15 biggest ships cause more pollution than ALL cars worldwide ([0]).

The problems are ships (which burn stuff that's essentially waste and
generally have no form of emissions treatments [1]), locomotives (these burn
diesel, but again, the vast fleet of old diesel locos doesn't carry any
adequate filters [2]), wood furnaces (in poor countries, where anything that
burns is used to heat and cook [3]), and factories where no money is available
to get their emissions under control ([3]).

Also, to clarify, I'm not after greenhouse gases, but after the stuff that
actually kills people. Greenhouse emissions are nasty but as others have
noted, agriculture is to blame here and not cars or anything else.

[0]: [http://www.gizmag.com/shipping-
pollution/11526/](http://www.gizmag.com/shipping-pollution/11526/)

[1]: see
[https://en.wikipedia.org/wiki/Fuel_oil#Environmental_issues](https://en.wikipedia.org/wiki/Fuel_oil#Environmental_issues)

[2]: [http://www.russfrei-fuers-
klima.de/themen/schienenverkehr/](http://www.russfrei-fuers-
klima.de/themen/schienenverkehr/) (german unfortunately)

[3]:
[https://en.wikipedia.org/wiki/2013_Eastern_China_smog#Causes](https://en.wikipedia.org/wiki/2013_Eastern_China_smog#Causes)
(though I have to admit, it's coal, not wood, but the result is the same)

~~~
jjtheblunt
If I recall, all that you cited above is far less damaging than livestock
agriculture.

~~~
mschuster91
Depends on the pollutants. What I cited above is mostly particulate or toxic
pollutants, livestock is a greenhouse-only problem.

------
mapt
One way or another, the author was charged with writing a hit-piece on diesel
passenger cars in order to put pressure on regulation to keep them out of the
US market. They did it poorly, with little factual backing. That's because
they don't have much of a case.

Clean diesel can be very clean. Clean gasoline engines are something we
created in the 70's, 80's, and 90's; We used to have an enormous smog problem
from tailpipe emissions, but we've basically solved it through regulation of
what sort of fuel gets made and what sort of emissions controls are built into
cars. With diesel trucks, we resolutely refused to make the corresponding
changes for several decades; It's going to take 20+ years to get the truck
fleet on the same footing as cars, and we only started the ULSD rollout about
10 years ago; we've only just begun major emissions level requirements in 2015
vehicles. The trucks you and I grew up around have no attempt to control
emissions whatsoever, due to the power of US industry lobbyists. There is very
little comparison to the clean diesels that are now a well-developed, highly
regulated chunk of the EU passenger car market.

The diesel emissions scandal was about a deliberate conspiracy within one
manufacturer, wherein software was written to turn off major emissions
controls in order to gain a very small mileage advantage, and then turn them
back on to pass emissions testing. It has no relevance whatsoever to the
practicality of clean diesel engines.

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mulle_nat
Article is low on numbers

"An air quality expert in Britain reported that much of it was “stale diesel”
from traffic emissions generated in European cities."

how much is "much of it" ?

and big on personal observation like

"As anybody who has seen the black smoke spewing out of the pipes of a big rig
as it changes gears can testify, diesel has a fatal flaw."

IMO a fluff piece.

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blacksmith_tb
The interesting thing about NOx and soot pollution is that it remains a local
problem, unlike the (higher) CO2 emissions from gas engines, which are just a
contribution to global climate change. In that sense, I'd say it would almost
be preferable to require all passenger vehicles be diesel - people could see
quickly why they should drive less... Many diesel owners in the US (myself
included) run varying amounts of biodiesel in their engines, which produce
slightly more NOx (generally), but less particulates.

~~~
justincormack
Unfortunately drivers dont mind killing people with their emissions it turns
out.

~~~
junto
People generally don't mind doing things that slowly kill other people or
themselves for that matter. Smokers are a prime example.

If the effect was immediate and those 9000 odd people just dropped to the
ground dead as you drive past them, we would see a more direct reaction.

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aurhum
Some of the sources used in this article are not at all of the quality I have
come to expect from the NY Times. Sources like the Daily Mail and
"www.searchautoparts.com".

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CodeWriter23
There's either some bias or flat out ignorance with this author. I'll start
with:

> In other words, a driver who steps on the accelerator of a diesel car may be
> filling the lungs of nearby pedestrians, cyclists, infants in strollers and
> other drivers with potentially deadly particulate matter.

Driving a diesel car is nothing like driving a gasoline car. In a gasoline
car, when you "step on the accelerator" you follow the horsepower curve,
revving the engine to 5000-5500 (perhaps higher) RPMs before shifting. This is
because the torque curve in a typical gasoline vehicle follows the horsepower
curve until you get close to the red line, typically 6500-7000 in modern cars.

In a diesel passenger car (using a VW TDI as a reference) the torque develops
early, peaking at about 2000-3000 RPM, then falls as you go past 3000. So if
you want to get going fast in a TDI, you keep the shifting going on at around
3000. With the way the DSG and ECU work in a TDI, that means running at about
1/3-1/2 throttle. Definitely not "stepping on it". Also note the red line on a
TDI is 5000 RPM.

As a side note, the TDI ECU's algorithm for detecting faulty inputs imposes
about a 1.5 second delay on actually opening the throttle if you floor it from
a dead stop. It's very counterintuitive if you need quick acceleration, you
have to give about 1/4 throttle, then slowly increase as the car starts
moving. Again, if you want to go fast, the car actually incentivizes NOT
stepping on it.

Second, and this is the one that everyone seems to fail to notice. The TDI
passes emissions when the bypass mode is disabled, putting the ECU into normal
mode. What normal mode means is the car more frequently cycles the Diesel
Particulate Filter (DPF), which reduces NOx emissions by accumulating soot in
the DPF then burning it by passing unburned fuel through the engine 1 out of
every 4 cycles while the system is in a DPF cycle. The unspent fuel lands on
the soot, then the heat from the following combustion cycle ignites it and
dumps mostly ash/greatly reduced NOx down the tailpipe. There are of course
performance and fuel efficiency issues with normal mode. With proper tuning of
the software it should be able to both meet emissions standards without
sacrificing too much in the drivability department. A decrease in mileage is
inevitable though.

VWs mistake in all this was failing to accept a 28/38 MPG (or 27/37) rating,
and insisting on 30/40 MPG (which likely came at the behest of VW Marketing).
Had they been willing to accept slightly lower MPG numbers, they would have
been in compliance with the law.

To me, all the kerfuffle seems a little overblown. I don't give VW a free pass
for breaking the law, they need to be held accountable. But this whole idea
that diesel is doomed seems very off kilter to me. Diesel produces fewer
greenhouse gases, converts hydrocarbons to kinetic energy most efficiently of
all internal combustion engines, has fewer emissions from ancillary chemicals
than gasoline like acetone and toluene (both unregulated at present). It truly
is the way forward until we can retool the worldwide vehicle fleet to be
driven by electricity (30 years minimum if we start right now).

When I look at this anti-diesel campaign, I look at it through the lens of the
Saudi's fear not of peak oil, but of peak demand. Diesel threatens to lower
the plateau of peak demand.
[http://www.bloomberg.com/news/articles/2015-04-12/saudi-
arab...](http://www.bloomberg.com/news/articles/2015-04-12/saudi-arabia-s-
plan-to-extend-the-age-of-oil)

~~~
sxcurry
Thanks for the reality check on this poorly written article. I think the
NYTimes should have asked you to edit it!

~~~
ars
Hardly a reality check, his post was quite misleading.

------
venti
If you want to know exactly what Volkswagen did in their software for the
emission control unit, I recommend this talk from last week's Chaos
Communication Congress:
[https://www.youtube.com/watch?v=xZSU1FPDiao](https://www.youtube.com/watch?v=xZSU1FPDiao)

------
foobar1962
"The diesel engine is inherently efficient: Even a heavy sedan can get as much
as 50 miles per gallon, while producing fewer carbon dioxide emissions per
mile."

There seems to be a common misconception about CO2 emissions from cars,
evidenced in this statement.

Burning hydrocarbons produces CO2 and water. The more burned, the more
emitted. The efficiency of the engine (and vehicle in total) determines how
much fuel is used while driving. More efficient = less emissions.

Diesel engines are thermodynamically more efficient by virtue of their higher
combustion temperature and pressure. It's this same high temp and pressure
that causes nitrous and sulphur oxide pollutants to form in the exhaust gas.
Hence there is a definite trade-off between high thermodynamic efficiency, and
NOx pollution.

Diesels are more efficient, but less clean.

------
revelation
This article is missing the forest for tiny NOx colored trees.

Sure, there is an indirect health problem with pollution, but there is also a
much more direct _health problem_ : cars causing fatal accidents. The best way
is hence to fix the problem at the root: personal cars do not belong in
cities, and _cars_ do not belong in pedestrian areas.

~~~
akamaka
Vehicle emissions cause 53,000 premature deaths in the USA every year:
[http://news.mit.edu/2013/study-air-pollution-
causes-200000-e...](http://news.mit.edu/2013/study-air-pollution-
causes-200000-early-deaths-each-year-in-the-us-0829)

I'd be happier to fix both problems at once, but fixing just one would go a
long way.

~~~
revelation
I've expanded on this in the other child comment, but of course banning diesel
cars doesn't solve the pollution issues.

There is no _healthy threshold_ for particulate concentration and other
pollution, even if safety standards want to create this illusion. It's a
continuous world, after all.

