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The Dirty Truth About 'Clean Diesel' (nytimes.com)
HughPickens.com writes: Volkswagen persuaded consumers it had created a new generation of so-called clean diesel cars — until investigators discovered that phony testing concealed that its vehicles emitted up to 40 times the permitted levels of pollutants during regular use. Now Taras Grescoe writes in the NY Times public outrage over the fraud obscures the much larger issue: "clean diesel" is causing a precipitous decline in air quality for millions of city-dwellers. Monitoring sites in European cities like London, Stuttgart, Munich, Paris, Milan and Rome have reported high levels of the nitrogen oxides and particulate matter, or soot, that help to create menacing smogs. Although automakers worked hard to convince consumers that a new generation of "clean diesel" cars were far less polluting, diesel has a fatal flaw. It tends to burn dirty, particularly at low speeds and temperatures. In cities, where so much driving is stop and start, incomplete diesel combustion produces pollution that is devastating for human health.
Fortunately, Volkswagen sold only half a million of its "clean diesel" cars to the American public before the emissions scandal broke. Today, fewer than 1 percent of the passenger vehicles sold in the U.S. run on diesel fuel. Europe is now scrambling to undo the damage. In London, Mayor Boris Johnson last year called for a national program to pay some drivers to scrap their diesel vehicles. In Paris, Mayor Anne Hidalgo has gained broad support for a proposed ban on diesel cars. "Last month, the signatories of the climate deal in Paris agreed that the world has to begin a long-term shift from fossil fuels to more sustainable forms of energy," concludes Grescoe. "Recognizing "clean diesel" for the oxymoron it is would be a good place to start."
Fortunately, Volkswagen sold only half a million of its "clean diesel" cars to the American public before the emissions scandal broke. Today, fewer than 1 percent of the passenger vehicles sold in the U.S. run on diesel fuel. Europe is now scrambling to undo the damage. In London, Mayor Boris Johnson last year called for a national program to pay some drivers to scrap their diesel vehicles. In Paris, Mayor Anne Hidalgo has gained broad support for a proposed ban on diesel cars. "Last month, the signatories of the climate deal in Paris agreed that the world has to begin a long-term shift from fossil fuels to more sustainable forms of energy," concludes Grescoe. "Recognizing "clean diesel" for the oxymoron it is would be a good place to start."
My own nose is able to tell that diesel isn't particularly clean burning.
... that comes out of the back of even new diesel vehicles on hard acceleration tells you all you need to know about how clean diesel really is. Yes, it emits less CO2 per mile than petrol/gasoline for the equivalent power output but thats where its enviromental credentials end.
If diesels pollute mostly at low speeds and temperatures, why not make diesel hybrids, which would allow the diesel to run at peak efficiency and/or cleanliness?
This makes a great story:
But nobody ever mentions the actual level - which is pretty damn important because 40 times 1 part per thousand is a lot more significant than 40 times 1 part per trillion.
Yes VW cheated - but lets not forget that the "Clean Diesel" TDIs are MUCH cleaner than the previous generation diesel cars (TDIs included) that were on the market. Anyone who has owned both can tell you, the clean diesel TDIs don't smell, never emit black smoke and the tail pipe stays clean and doesn't fill with soot the way the old cars did.
VW broke the law and should be punished, but this isn't the BP oil spill.
So what, Diesel is much more effective than gas cars. You can go 3 times the distance on same volume of fuel. A good engine has less CO2 compared to the trucks most of America drives. America has a skewed system of protecting local auto industry, they basically don't measure CO2 at all, they care about a short living, harmless (because of the short life) NO. Think about it - a large GMC van/suv on a truck frame, with 4 or 6 liter engine, it is much more polluting than a small 1.5/2l not so "clean" diesel. You have to think long term - about greenhouse gases. NO is not a greenhouse gas, CO2 is.
... nonexistent.
Wow...hyperbole much?
Before taking a job in systems administration, I used to hold a CDL and drive regional/long haul for a trucking company. Everything we had was, of course, diesel because we run mostly on highways and at fourty tons our speed isnt a huge priority. in fact, we sometimes drive under the speed limit to make up mileage/save fuel based on projected consumption. the diesel car, for all its promises, is a break-even proposition at best.
speed: outside of a few concept sports cars, diesel isnt about speed but torque. in trucking we compensate by turbocharging our engines, to make the lives of normal drivers easier. without turbos it would take ten minutes or more to get up to speed. the tradeoff is bad mileage.
coldstart: cold start problems will always exist. for those of you in minneapolis or duluth, I see you shopping for the same antigel treatments and fuel additives for your audi that I use on my freighliner, and the truth is theyre awful for emissions and even worse for mileage. emissions systems are often programmed to detect and correct for them. they dont always work in the coldest weather, and consumer autos dont have fuel tank heaters or radiator louvres.
"cleanliness": no. hell no. On my Freightliner CL Columbia truck, I had no less than 6 gauges for the emissions system. everything from exhaust backpressure to air-in temp, exhaust temp, and temperature monitors on the scrubber DPF CV. sometimes id sit idling for 15 minutes just to make sure my emissions layout was "green" before taking off, because if its not ill blow smoke for miles down the highway. urea tanks and injectors need to be filled and cleaned respectively at regular intervals, and in long haul trucking this is a no brainer. we have a very user friendly interface for monitoring and planning refill. but car drivers? do you really want to worry about the car dropping down into "limp home" mode when you forget to top off the tank? it could strand you on the highway at 24 miles per hour.
finally, theres the godless process of smogging. what might fly in one state, wont in another, and as more states adopt emissions standards that require smog checks, more of these older diesel cars will fail outright. for most trucks, if you can smell the diesel smell, you wont pass.
Good people go to bed earlier.
True, but let's not forget that the USA is generally HUGE compared to most European countries and the USA has an overall population density which is pretty low. This is why we spend so much time in our cars, it's a long way to work and Grandma's house.
Let's also not forget that automobiles have vastly improved their emission standards and efficiency over the last few decades. I remember the yellow-brown haze which blanked LA nearly continuously in the 80's and have noticed that it's not nearly as bad anymore. So all is not lost.
"File to fit, pound to insert, paint to match" - Aircraft Maintenance 101
Protip: I would have modded this up if you removed the first four words.
So many good posts end up at +1 because of hyperbole or bombast. Make a good point and it stands on its own.
Better off with a gas-electric hybrid. Electric motor has even more low-end torque than diesel.
Depends on the application. Diesels-electrics are used in locomotives and I think they would probably work fairly well in similar applications like in large cargo hauling trucks. I think it wouldn't make sense for a small city runabout or a family sedan but for big trucks I'm kind of surprised we haven't seen it worked on already. Diesels are actually best in steady state applications which is why they are great for trucks. Yes they are torquey but their fuel efficiency is their primary draw and that comes from operating at (relatively) constant speeds.
Your comments highlight the crux of the problem. Back in the day, inefficient (read truck like) diesel were shooting out black smoke. That particulate is large in size (10 or 100 of microns) that you actually "see". Improvements in efficiencies (both in combustion and trapping) made modern "clean engines" reduced the size of particulate to few microns. Those are much more difficult to see. Yet they are far more dangerous. Large particulate is trapped in your upper respiratory tract, the fine stuff gets deep in your lungs, often bioaccumulaating like abspestos does. You know how the stoey goes. Not because you don't see it it means it's not there... Next time stick a paper towel on the exhaust of your cold diesel and leave it there for a few minutes. Look at the color. Now you have somerhing to "see".