Is a diesel engine or a petrol/gas engine and vehicle more environmentally friendly and why?

Question

I've read that the diesel has greater emissions and has more sulpher so the diesel emissions are dirtier - is that so?.
So why is the diesel engine considered more environmentally friendly? Is it because of the feul efficiency of a diesel vehicle means you use less feul? And if so, what is that efficiency - a good diesel vehicle will get maybe 30% - 50% better mileage so does that mean the emissions are less that 30% - 50% worse than the gas/petrol engine?
Or are there other factors in this arguement that I haven't thought about?

Answer 1

Diesel engines are a slight improvement over gasoline engines. For starters, ultra-low sulfer diesel (ULSD) has become the norm, so sulfer isn't a concern with diesels anymore.

In terms of fuel efficiency, diesels improve over gasoline burning cars by 20-40%. However, diesel also emits 15% more greenhouse gas emissions per volume than gasoline, so it's a 5-25% improvement overall in terms of greenhouse gas emissions.

Diesels can usually also be run on biodiesel, which makes it a potentially environmentally-friendly alternative, because biofuels are part of the carbon cycle whereas burning petroleum products adds new carbon to the atmosphere.

"the Life Cycle Inventory Study of Biodiesel and Diesel Fuel completed in May 1998 by the U.S. Department of Agriculture and the U.S. Department of Energy...concluded that biodiesel reduces net emissions of CO2 by 78% compared to petroleum diesel."

Answer 2

I don't know about trucks, BUT my 1982 VWdiesel rabbit still gets 40 miles to the gallon. So I'm not too concerned about the cost differntial vs gas! Diesel is currently a few cents more expensive than the highest grade of gas, and I suppose it'll stay that way. But my car is still cheaper to operate than a new gas car. I do have an extra engine which I plan to rebuild to hopefully lessen my car's environmental debt. The original owner's manual explicitly says that no warmup period is required. You turn the key on, wait 15 seconds or so for the glow plugs to warm up, then engage the starter, take your foot off the clutch and go on your way. The manual explicitly says never to idle the engine.

Answer 3

In January 2007, the EPA finally set new smog rules for diesels. The auto industry was waiting for that to happen, and now they're introducing a bunch of clean, faster engines.

Diesels emit different types of pollutant.
Gas engines tend to emit CO and HC.
Diesels tend to emit SO2, NOx, and particulate.

Gas engines use catalysts to eliminate CO and HC, but lead would destroy the catalysts, which is why there is unleaded gasoline.
As of 2007, new diesels use catalysts to eliminate NOx and particulate, but sulfur would destroy the catalysts, so there'll be low-sulfur diesel. That eliminates SO2.

But the #1 reason diesels are better is that any diesel can run biodiesel, which is an efficient, practical biofuel. Ethanol is NOT efficient or practical, it takes too much energy to distill it.

Hybrid diesels make a lot of sense. I expect to see them in the next generation of plug-in hybrids.

Answer 4

Gasoline engines have been more environmentally friendly, but that is changing with new technologies. I see a future, not long away where the diesel engine will be dominant.
The whole ides of ethanol powered cars is absolutely NUTTY. It is costly, inefficient and shows little or no environmental advantages.
The pollutants are different, but on balance, not much help.
Diesel, on the other hand lends itself to easy use of bio-diesel which is lower cost, more efficient and less polluting.
The diesel engine technologies now under development show significant improvements in both efficiency and reduction of pollution.

Answer 5

I just wanted to add some updates on Diesel from Europe where over 30% of the vehicles are diesel.

I personally drive an over 45MPG diesel and its not an hybrid. It accepts vegetal oil.

THE PROBLEM OF PARTICLES HAS BEEN SOLVED about 5 years ago using electro-particule filter.

Moreover Diesel through direct injection is really nice to drive, offers a large torque and has as much "pick up" as regular fuel.

Answer 6

An hybred vehicle is equivalent to a modern diesel vehicle. So why don't they make an hybrid diesel?

Answer 7

Diesels are notoriously filthy. Look at all the smoke some put out. They're just more efficient

Answer 8

If you consider enviornmentally friendly not emitting pollutants, diesel is better, if you consider it less CO2, diesel is better for the same car.

You must keep either car tuned properly though.

Answer 9

Diesel rules I have an Isuzu FRR and I love it. someday i can go bio if i want or not. Just having the option to make my own fuel is great.

Answer 10

I am going to tell you.

#1 Biodiesel is expensive
#2Nobody really knows the whole story on Biodiesel emmisions. It is really a concern among atmospheric chemists, but is in the preocess of being studied.
#3 Ethanol is not a bad idea, its just that corn is not the best way to make ethanol. Rapeseed and soy may be much more efficient. But with ethanol you gotta worry about a wino poking a hole in your gas tank and pouring himself a drink.