Diesels Are Inherently More Polluting

[famman33]

Well now that the VW cheating scandal is out in the open, light has begun to be cast on the open secret that diesel engines affect human health and impact the atmosphere far more than petrol engines.

While this might tend to hurt the feelings of oil-burner aficionados - the truth cannot be denied any longer. (I know that I run the danger of earning brickbats here. )

Or maybe more enlightened experts might like to weigh in on my side?

You might like to read more on the latest about VW diesels at the below link and contribute your two pence to the issue at hand.

Source: VW scandal - What

 

[nag2fat]

I would like to differ to your point here. In the VW case, when the testing is done, the emissions are well under control and it doesn't affected the environment. However this should be the case all the time and if the software was removed or redesigned, the emissions will be well under control. And the irony was that the VW promoted their diesels as "Clean Diesels" and it will never harm the environment. Waiting for the final conclusion of this issue..

Also please find the below article from Clickgreen.

"Which fuel type is more environmentally friendly, petrol or diesel? Common knowledge would make us reply “diesel” right away, as engines running on diesel emit less carbon dioxide or CO2, and less CO2 is better to decrease the amount of greenhouse gases in the atmosphere.

However, being eco-friendly isn’t as simple as emitting less CO2. Diesel-powered vehicles may emit 20% less CO2 per kilometre travelled, but they may be more harmful for local pollution due to the tiny particles that are released by diesel engines into the atmosphere. The question really isn’t which fuel or engine type is more environmentally friendly, as no form of engine that uses fossil fuels will ever become good for the environment. Rather, we should look at which has the capacity to inflict the least amount of damage to the environment.

The Brotherhood of Bad Boys

We have already been introduced to CO2 and how excess amounts of it is bad for the environment, but it isn’t the only one that brings the world harm. The use of engines, both petrol and diesel, produce the following:

• Carbon monoxide or CO – Carbon monoxide, produced by petrol engines when a car is warming up, is lethal and there have been many accidents involving carbon monoxide poisoning

• Suspended particulate matter or SPM – this is what the tiny particles emitted from the exhaust of a diesel engine are called. Soot is a tell-tale sign of SPM. Modern diesel engines are usually fitted with filters to lessen the amount of SPM emitted, but the bigger problem lies with older diesel engines that do not have particulate filters

• Hydrocarbon or HC – Hydrocarbons contain harmful chemicals such as benzene, which causes cancer. Petrol engines emit higher levels of HC than diesel

• Nitrous oxide or NOx – Nitrous oxide combines with the lowest level of the ozone layer to form smog. New diesel engines produce a higher amount of NOx than new petrol engines, but petrol-powered cars produce more NOx as time goes by.

As we can see, when it comes to carbon monoxide, carbon dioxide, and hydrocarbons, it’s better to go with diesel engines. However when it comes to particulate matter, diesel engines lose to petrol. Both stand on equal ground when it comes to nitrous oxide.

Catching up with diesel

Diesel may be the lesser evil of the two, but petrol is quickly catching up with the greening measures. New petrol engine models and hybrid engines are being developed to emit significantly less CO2 than the engines of old, without sacrificing vehicle performance, reliability, and fuel efficiency.

Diesel isn’t resting on its laurels, however. With the demand for diesel on the rise, the EU has started to look for ways to make diesel less harmful to the environment by reducing the total number of SPM per kilometre. New diesel engine technology is also being developed to monitor fuel combustion, reduce emissions, and improve energy efficiency. Devices such as improved catalytic converters and particulate filters are able to reduce the bad emissions by as much as 90%. That’s all good, and for the sake of the planet, let’s hope it gets even better."

 

[famman33]

For sure diesels are the more economical but you might like to read up on the following:

Anumita Roy Chowdhury, head of Centre for Science and Environment's Clean Air campaign, said, "CSIR has omitted to mention the serious health risk associated with diesel emissions. It is now well known that WHO has concluded that diesel exhaust is a human carcinogen and is in the same class as tobacco for its strong link with lung cancer."

Source: CNG is safe, as clean as Euro-VI compliant diesel - The Times of India

 

[nag2fat]

For sure diesels are the more economical but you might like to read up on the following:

Anumita Roy Chowdhury, head of Centre for Science and Environment's Clean Air campaign, said, "CSIR has omitted to mention the serious health risk associated with diesel emissions. It is now well known that WHO has concluded that diesel exhaust is a human carcinogen and is in the same class as tobacco for its strong link with lung cancer."

Source: CNG is safe, as clean as Euro-VI compliant diesel - The Times of India

I feel that India is not that strict in emissions when compared to US. Yes. The diesel emissions is dangerous. Hence manufacturers are using that much filters and converters to make the diesel less pollutant.. However after this VW issue lets see where this heads to... In some articles I read that diesel cars itself may be banned in US(Mostly it will be a hoax).

 

[ameyam]

Guys,

Diesel engines are some of the cleanest if maintained & operated properly. Its for one simple reason- the working fluid in diesel engines is air! Air is taken in, compressed and fuel is injected at the very end of the compression stroke. This means that it can run at a very lean fuel air mixture. More air means more contact between fuel & air molecules resulting in cleaner combustion. The fuel burns by the heat of compression alone, hence the correct name for diesel engines is compression ignition engines (CI engines) There is only one catch- when the engine is cold, the required temperature is not achieved by compression alone and the compressor that feeds the engine is not yet upto its optimal rpm range. So fuel air mixture is rich leading to incomplete combustion i.e. smokey startup

While most petrol engines, correctly called spark ignition or SI engines, now also use air as working fluid by using fuel injection instead of carburetor, the petrol molecules will not combust effectively if the fuel air mixture is not within the stiochometric limits. This is because the leaner mixtures do not have sufficient concentration in the charge for flame propogation from the plug through the charge. So petrol engines can only be made clean upto a point

VW's case is different. They tried to con the stricter western norms to be able to sell more at lower costs.

Ameyam

 

[Akash1886]

If I may speak here friends, See in today's time the OEMs operating in India are more conversant with govt. agencies and their norms for vehicle emission. India is considered to be one of the worst-hit countries when it comes to pollution. Now the major cause of environment pollution can't be here confined to cars/multi-axles alone. You see, diesel gen-sets are equally contributing in raising the pollution levels that too affects the health of the people. In today's time you can't make out the actual difference in petrol and diesel engines at large because with time, the technology has changed and refined engines have been coming in current line of cars here. Take for Eg Creta Diesel once you drive it you'll get to know how refinement has changed the total performance aspect and believe me neither by its emission nor by its NVH can the people be harmed. You see, how can a machine excessively pollute? The reason for excessively polluting machine is mainly the fuel adulteration which is rampant in India and then comes the periodic maintenance and thirdly is the way of operation. Now if one uses adulterated fuel then the life of engine reduces and so does the life of engine parts reduce thereby making it more susceptible to pre-mature wear-tear and ultimately causing excessive pollution. The same thing happens with home/official gen-sets. VW-Audi-Skoda and other international OEMs are really concerned of their image specially in growing markets like India. They are well aware of the fact that if on one hand they are given the opportunity to establish here, on the other hand their activities are being monitored as well. So, before they do any such scam here, they'll think 10 times. The agencies and unions at present are not at all forgiving. In their home countries, they are like the people who are acting as "King Makers" (People who fund govt. activities and provide assistance at times of govt. selection) and they are free to do as their will until one fine day, a bug erodes their clever deeds and explodes it in media. I'll tell you something, there is a difference how media reports such acts in other countries and in India. In India, by now, all their plants would have closed if this thing would have happened here and you can see, even after the removal of officials and the questionable device from the cars, the brand is operational which means, VW had the plan B ready in advance to save itself. So, no matter how well laid out the legal rules in other countries are, culprits can find and take advantage of the loophole.

Coming to thread subject, Diesel engines are now quite well groomed and don't pose a serious threat to environment and also have considerably less carbon foot-prints if you compare them with diesel engines of 10 years back. Also, we can't blame the engine because, its our responsibility to maintain the diesel car if we own one. If one doesn't care for it then its not the machines fault rather its retarded attitude of the owner.

Saying diesel engines pollute more to me appears as "Blaming the product unnecessarily simply because of one's screwed up knowledge of maintaining and operating it correctly".

OT: In this whole VW scam, I tried to analyse since yesterday, that this device in question was being used by the brand for so long, why did it come out so late? Why didn't anyone speak up earlier. Is it something that leaked all of a sudden? I do sense something fishy in its roots.

Regards

Akash

 

[nag2fat]

OT: In this whole VW scam, I tried to analyse since yesterday, that this device in question was being used by the brand for so long, why did it come out so late? Why didn't anyone speak up earlier. Is it something that leaked all of a sudden? I do sense something fishy in its roots.

Regards

Akash

What I understood was, the software adjusted when it deducts that emission testing is done and significantly changed the operations of its powertrain to reduce emissions during the tests.

That detection was likely based on a combination of sensor data from the car, which might include steering angle (since cars on dynamometer tests don't make turns), front-wheel versus rear-wheel rotation speed, and a variety of other factors.

And please find the below article on how it was discovered

"This is one of the more interesting parts of the story: It wasn't discovered by the EPA at all, but by a clean-air group that tested VW diesel models to confirm its hypothesis that the latest diesel cars complied with all emissions standards while remaining much more efficient than comparable gasoline cars.

As recounted by Bloomberg, the International Council on Clean Transportation (ICCT) had studied European diesel cars and discovered that the on-road emissions of some models were notably higher than those measured in lab testing.

So the group decided to replicate its tests in the U.S., which then had much stricter emissions limits (known as Tier 2, Bin 5) than the Euro 5 standards in force in the European Union until this year.

They tested the cars on a dynamometer, or "rolling road," then measured their emissions in real-world use with a variety of speeds, road types, and demands on a road trip from San Diego to Seattle.

“We had no cause for suspicion,” John German, the ICCT's U.S. co-lead, told Bloomberg. “We thought the vehicles would be clean.”

The U.S. models too proved to have on-road emissions far higher than the maximum legal limits, so high that German termed the results "shocking."

On the open road, a Volkswagen Jetta TDI blew through the U.S. nitrogen oxide (NOx) emissions limit by 15 to 35 times. A VW Passat TDI (with urea aftertreatment) was 5 to 20 times the maximum.

A BMW X5 xDrive 35d diesel crossover equipped with urea aftertreatment and tested at the same time, however, met the emission limits under all circumstances.

The U.S. EPA and CARB opened a joint investigation into the cars in May 2014, but it was not publicized.

Last December, VW recalled nearly half a million cars for a software patch to fix the problem--but CARB found it didn't enable the cars to meet the regulations. Matters came to a head on July 8, when CARB informed the EPA and VW of its findings.

This month, the EPA refused to certify VW's 2016 TDI models for sale, based on its real-world testing of the vehicle's emissions--which exceeded the legal limits, even though its lab tests didn't.

That's when Volkswagen admitted that it had installed the "defeat" software. The EPA went public within a few weeks."

And please find the link below(letter sent by EPA to VW)

http://www3.epa.gov/otaq/cert/documents/vw-nov-caa-09-18-15.pdf

 

[famman33]

HERE IS MORE DIRT ON THE DIESEL SCAM

Apparently diesel engine makers have been indulging in this standard trickery practice since the 1990s!

Both Caterpillar (of USA) and Volvo (another European manufacturer) had their trucks cheating in the lab tests but emit more nitrous oxide (NOx) as they traveled longer distances at constant speed on real roads.

As the below article clearly elucidates, there are limits to clean diesel technology. Read more at the link below:

Source: Volkswagen's appalling clean diesel scandal, explained - Vox

 

[Suryaputhra]

Guys,

Diesel engines are some of the cleanest if maintained & operated properly. Its for one simple reason- the working fluid in diesel engines is air! Air is taken in, compressed and fuel is injected at the very end of the compression stroke. This means that it can run at a very lean fuel air mixture. More air means more contact between fuel & air molecules resulting in cleaner combustion. The fuel burns by the heat of compression alone, hence the correct name for diesel engines is compression ignition engines (CI engines) There is only one catch- when the engine is cold, the required temperature is not achieved by compression alone and the compressor that feeds the engine is not yet upto its optimal rpm range. So fuel air mixture is rich leading to incomplete combustion i.e. smokey startup

While most petrol engines, correctly called spark ignition or SI engines, now also use air as working fluid by using fuel injection instead of carburetor, the petrol molecules will not combust effectively if the fuel air mixture is not within the stiochometric limits. This is because the leaner mixtures do not have sufficient concentration in the charge for flame propogation from the plug through the charge. So petrol engines can only be made clean upto a point

VW's case is different. They tried to con the stricter western norms to be able to sell more at lower costs.

Ameyam

Sir are you a post graduate mechanical engineer.
-suryaputhra

 

[ameyam]

No. I just remember what i learnt in college

My specialization was in auto engineering