Whats available in the "other world"
This site has a pollution calculator as we all know. I plugged in the VW Jetta Diesel 1.9 Liter automatic and Honda Civic Hybrid II for comparison. The VW diesel produces 750% more nitrous oxide than the hybrid over the same miles.
Nitrous oxide is the air poinson that is responsible for ozone problems, greenhouse effect, and global warming. The remaining characteristics are similarly problematic for diesel engines as far as pollution except for carbon monoxide, which is twice as high with the hybrid vehicle.
Overall, the "best" diesel engine is a huge polluter compared to one of several good hybrid offerings.
The lack of environmental friendliness of the "best" diesel offering makes it a deal killer for those who care about the environment.
MOS - couldn't disagree with you more. Diesels are NOT responsible for 750% more "nitrous oxide" emissions (nitrous oxide - N2O - is NOT the same as NOx - oxides of nitrogen). N2O is a greenhouse gas (mainly because of their long atmospheric lifetime) but NOx is NOT. It's my understanding that gasoline engine vehicles emit N2O when cold started because their cat converters aren't hot enough to completely reduce the NO to N2 and O2, thus some of it is only partially converted - to N2O. So, if anything, gas engines are responsible for MORE greenhouse N2O emissions.
Virtually all of the NOx emitted from diesel engines is in the form of NO (nitric oxide). NO DEPLETES ozone (smog). The weekend effect studies that I have mentioned in previous posts show that reducing NOx relatively more than VOCs and CO will likely not improve air quality (smog) and may actually make it worse.
"EPA Rule Is Making Ozone Smog Worse
The U.S. Environmental Protection Agency (EPA), which is forcing Americans to spend billions of dollars per year to address ozone air quality, is actually making the situation worse...."
Furthermore, "tailpipe" emissions don't take into account evaporative emissions of highly volatile gasoline. These VOC emissions decompose into secondary organic aerosols (fine PM) and formaldehyde formation. Diesel fuel of course has very low volatility (and biodiesel even lower). So you have to take that into account when evaluating the environmental impact of a particular vehicle.
"Nitrous oxide is the air poinson that is responsible for ozone problems, greenhouse effect, and global warming. "
Wrong again. The gas most responsible for the greenhouse effect and global warming is CO2, of which diesels produce less than the equivalent gas engine, both during driving and during the refining of the fuel. It is CO2 that is regulated everywhere else in the world as a greenhouse gas.
Get your facts straight.
Note the pie chart. Carbon dioxide accounts for 82% of greenhouse gas emissions; nitrogen oxides account for 5%.
What's better for global warming: a 99% reduction in NOx, or a 30% reduction in CO2? I'll do the math for you. Based on that pie chart, a 30% reduction in CO2 (typical with a diesel engine) results in a 25% overall reduction in greenhouse gasses.
A 99% reduction in NOx, results in a 7% overall reduction in greenhouse gasses. Even eliminating NOx totally will have nowhere near the impact of a 30% reduction in CO2.
Now I'll grant you that a hybrid can reduce both NOx and CO2, the former more so than a diesel. However the most reliable overall strategy to reduce greenhouse gasses is by reducing CO2 significantly. In Europe, close to 50% of new cars are now diesels (replacing already fairly efficient small-displacement gassers).
In the USA, the only hybrids that really count towards signficantly reducing CO2 are the Prius, Civic and Insight (and maybe soon, the Fit); hybrid SUVs and "performance" hybrids like the Accord will only make a small dent in overall CO2. Efficient hybrids still only represent a tiny fraction of the car market. And as long as the economics of ownership are still questionable, it will likeley remain so.
On the other hand diesels have good ownership economics in their present form, have excellent efficiency, and if 50% of the market were diesel, all things being equal, within maybe 10 years, perhaps faster with incentive programs, overall greenhouse gas emissions would go down by about 15% in N. America. Ideally, a mix of diesels (for long-distance work) and hybrids (for urban work), and abandonment of oversized SUVs, would lead to a massive reduction in CO2.
...and MOS and others still refuse to use clean
diesel fuel and top of the line diesel engines when
he argue his point...this has been said before so I
dont think it will ever reflect in his messages
Well here's a link, the green house gases on the prius are much better than the similar sized TDI and civic. I think that in Europe the benifit isn't diesel vs gas I think it's small car vs large and the fact that we drive longer distances. I think gas prices have to get really painful to get Americans to go small, and drive slower. A Ford Explorer gets an epa 15/21 and puts out 10.9 tons of greenhouse gases a year. and a Honda Accord V6 gets 20/29 and puts out 7.9 tons of greenhouse gases. So by my calculation getting Americans to buy Civics instead of Accords gets you a 30% reduction.
and buying a wagon instead of an explorer gets a 34% reduction, and a better SUV gets a 20% reduction and the Hybrid SUV gets a 42% reduction in greenhouse gases.
In answering the Hybrid vs diesel question, the emphasis for me is on air quality and fuel economy. On both counts the Hybrid vehicles are the better alternative and is also where the emphasis is in passenger car production for the United States.
The calculator on this website that compares vehicles on both fuel economy and air quality shows quite a difference between the best diesel offering, the VW Jetta 1.9 Diesel; and the Honda Civic Hybrid.
The VW Jetta diesel clearly produces 750% more Nitrous Oxide than the Hybrid, and and much more pollutants in most of the other parameters.
In answering the question, we can only consider what the reality is, not the potential of things that may never come to fruition, and arent receiving much emphasis in the US car passenger market.
Steve is right. The Hybrid SUVs and other larger hybrids, while not getting particularly exciting fuel economy, do benefit in the arena of air quality quite a bit relative to similar size diesel and gas alternatives