European Carmakers defend diesel to lower CO2 emissions

Well the whole EU infrastructure is slanted to diesel much the same as US is slanted to gaso. So we have corn ethanol, while Europe is awash in yellow flowers of rapeseed oil for biodiesel...not to mention long standing EU refineries diesel maximized and high cetane specs which are hard to match in USA. USA was just lucky that gasoline turns out to probably be the cleaner eco-choice, but that was not the original intent with leaded gasoline etc. Prius itself changed the whole gaso-is-dirtier-than-diesel paradigm by getting diesel-like MPG with near zero tail pipe emissions.

 

Clean diesels not so clean, apparently

 

good point, padding their own pockets at the expense of users with high maintenance vehicles.

 

Summary, diesel cars emit more on the road than in lab tests.
There was some that looked at gasoline cars. Laboratory versus real world: Discrepancies in NOx emissions in the EU | International Council on Clean Transportation
The gasoline cars did better, and the diesels really haven't improved over Euro 3 on the road. It is only European cars looked at there, and while the quoted study looked at three American models with 12 European ones, the basic report didn't break them out from there graph. Most of the tested cars were at the just above failing Euro5, and one got the Euro6 rating. EPA test has slightly stricter limits and the new test cycles should be closer to real world*. So it would be interesting to see how the American models did. better testing will lead to cleaner cars.
http://www.theicct.org/sites/default/files/publications/ICCT_PEMS-study_diesel-cars_20141010.pdf

Diesel emission control technology is still relatively new. It gets a head start due to gasoline emission control know ledge, but the gasoline cars have been rolling with gear more sophisicated than a two way catalytic converter for decades now. Diesels didn't start until 2007 or so in the US. Then direct injected gasoline engines, and some port injected ones, would need exhaust filters if they were officially tested for particulates.

"As the FTP cycle does not cover the full range of possible speed and acceleration conditions, emissions under off-cycle conditions are effectively uncontrolled. Manufacturers can and do take advantage of this to increase the power output and performance of their vehicles under off-cycle conditions. As a result, vehicle emissions may increase dramatically under these conditions. For example, most gasoline passenger car engines use a rich mixture and shut off exhaust gas recirculation at or near full throttle, causing huge increases in CO emissions. Such increases associated with high power and load conditions can soar as high as 2,500 times the emission rate noted for stoichiometric operations. Although most vehicles spend less than 2 percent of their total driving time in severe enrichment conditions, this can account for up to 40 percent of total CO emissions. NOx and HC are also increased.
...
CARB further concluded that these effects may be responsible for emissions in the South Coast Air Basin of California being as much as 7 percent higher for nitrogen oxides, 20 percent higher for hydrocarbons, and 80 percent higher for carbon monoxide thanprojected by the current emission models.
...
EPA tests of several vehicles with the air conditioner running showed NOx emissions nearly double those without the air conditioner, although fuel consumption increased only 20 percent."
http://www.un.org/esa/gite/iandm/faizpaper.pdf
(page 48 by the PDF search)

*While the updated EPA procedures added 3 new test cycles that should help cover some of those deficiencies, they aren't truly mandatory as we learned from Ford's shenanigans.

 

Diesels are not even close in City/Urban cycles compared to pure hybrids:

• regenerative braking
• avoiding piston/crank/valve drag by turning engine off

It is ONLY on the highway were every engine has to run that that gas, diesel, and hybrids come close.

Bob Wilson

 

Smog over Britain: Air pollution ‘will get worse’ as more drivers choose diesel powered cars - Climate Change - Environment - The Independent

Diesels are now public enemy number one here. Tax incentives are now against them and the fuel is more expensive. Many cities are also very close to introducing low emission zones which will exclude diesels.

"Diesel engine emissions pose the single greatest public health challenge for UK cities in the years to come, claims Timothy Baker of King’s College London."

The low-cost electric car revolution - Telegraph

"Sales of ultra-low emission vehicles (ULEVs) saw a four- fold increase in January by comparison with the same month last year, matching the growth seen in ULEV sales in 2014. January’s increase comes despite the traditionally slow new car sales in the new year."

If you're not part of the solution, you're part of the problem.



Fancy a lung full of that? No, me neither.

 

No technical reason why diesels couldn't have those technologies, or even be a hybrid. Compared to a gasoline car, they should do better in the city due to their lower idling fuel consumption and lower end torque.

I wonder what the Mazda6 diesel is rated at? The gas version with iEloop regenerative braking(which includes active grill shutters, and I think start/stop) is rated 2mpg higher, both city and highway, on the EPA.

 

Actually, current diesels (NTDE) are considered one of the "cleanest" technologies available from a full life-cycle emissions perspective. Gasoline has relatively higher emissions in the fuel production cycle, including NOx.

A 2009 report by the National Academy of Sciences (NAS) concludes that NTDE has one of the lowest public health and environmental "damages" of any technologies/fuel pathways that were considered in the study.

National-Academies.org | Where the Nation Turns for Independent, Expert Advice
(Press Release; full report available at top of press release - Page 350 (of 506))

Several more recent reports have supported the NAS study, including one published late last year (2014) in PNAS.

Electric Cars May Not Be Better For The Environment In Places Where Power Comes From Coal

Life cycle air quality impacts of conventional and alternative light-duty transportation in the United States (Paper abstract)

 

Still gasoline and electricity are in the USA displaced from urban populations. There is a lot to be said for dilution.

Bob Wilson

 

Proof positive.
You can 'statistically' prove ANYTHING if you manipulate the data.

Concur....

 

The reverse is true also.

 

I'm not sure about that. When we look at euro 6 or current epa regulated light diesel car and trucks they are so clean when properely maintained, they should stay as a clean fleet.

The problem is the old ones.

Yep that is an old one, or one that actually had modifications (illegal in many states) to produce more exhaust. The trick is to pull all the old ones, the poorly maintained ones, and the ones modified to pollute off the roads.

I know texas regulations pull the poorly maintained gasoline or new diesels off the road. If you have an old polltuter diesel, it doesn't even have to get tested as we don't make test equipment that can handle that much pollution. Its one of of those bad old grandfathering laws, made to let people own vintage pick up trucks, but with a loophole so large all the non-vintage old polluters can drive right through.

 

Driving around Alabama, I'm pretty sure a smoke detector and carbon monoxide detector would be set-off at least every other week.

Bob Wilson

 

It's true that all cars and trucks need to be properly maintained to stay clean, but this seems to be much more true for diesels, which only seem to be almost as clean as proper petrol cars if you bend the numbers the right way and then only after herculean efforts are made to clean them up....recently.....maybe.....and expensively.

No Thanks.

 

I agree, but according to the latest version of the GREET model, the following are the relative life-cycle urban emissions of the generic 2015 mid-sized cars...

	Column 1	Column 2	Column 3
0	Emission (g/mi)	2015 Diesel Car	2015 Gasoline Car
1	VOC (Urban)	0.188	0.316
2	CO (Urban)	1.897	2.007
3	NOx (Urban)	0.196	0.140
4	PM10 (Urban)	0.021	0.026
5	PM2.5 (Urban)	0.010	0.014

GREET uses EPA's emissions factors for the pump-to-wheels emissions...

 

How many years have I been hearing Wxman tell us that the upcoming diesel is *so* much better, that we should change our negative opinions? I've lost count

 

I do agree with Machione about one thing though:
Set the standards, and let the technologies compete.

I vote for Prius level tailpipe and CO2 emissions for non *EVs

 

Couldn't that be said of gasoline cars in the late 1970's?

 

I don't recall ever trying to talk anyone into switching to diesel. It gets tiresome hearing commenters tell me how I'm a virtual criminal because I drive a diesel vehicle and "pollute" everyone's air. I'm just providing some data to counter that myth.