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Also, rather than just basing everything on relative concentration, the standards should also take into account overall output. Thus, a Diesel Hummer wouldn't be favored over a Diesel Smart Car due to emission concentration while the Smart puts out only a fraction of the total emissions of the Hummer.
As far as maintenance on aging vehicles. It can become astronomically expensive to repair the emission system on a 20+ yr old car that only gets driven a few thousand miles a year. St. Louis has exempt all pre-ODB II vehicles which is a step forward. But, the 20+ yr old vehicles are the minority of the vehicles on the road, and they usually get driven less than the newer vehicles.
The efficiency of the engine tallies quite well with the ppm of pollutants in the exhaust.*Since they are seeking to improve efficiency that's what they measure.The fact is that mopeds and 4by4s simply aren't the same thing. You cannot directly compare miles per gallon for the two.Don't forget that the gas guzzlers already pay more tax because they use more fuel (which is heavily taxed).* an ideal, lean-burn engine would produce about 140000 ppm CO2, 0 ppm NOx, 0ppm CO, 0ppm hydrocarbons and zero ppm SOx no matter whether it was diesel or gasoline and whatever the engine capacity.
Currently the US & others still have very lenient taxation for 'gas'
This is going a bit 'off topic', don't ya think guys?
I don't really care about how important realities are dealt with. What I do care about is resource depletion and environmental degradation. I am especially concerned that nobody wishes to put a cost on using the rapidly diminishing commons. We are approaching another tragedy of the commons and problems with automobile emissions and fuel usage are a sizable component. (Geezer, my taxes are really quite reasonable).
Apart from rush hours, most of the stuff is grossly underutilized.
Quote from: Geezer on 08/12/2010 01:48:16Apart from rush hours, most of the stuff is grossly underutilized. Which is why the Seattle-Tacoma trains only run during rush hour, and primarily in one direction.
"The problem is that for public transportation to be practical, there has to be access. I.E. A bus should go within 1/4 or 1/2 mile of every place in the city, and should do it from about 5AM to 2AM. "No it doesn't.Public transport IS practical. Just about everywhere has it. Practically none run that sort of schedule.
I've heard that California has had particularly strict emissions standards (for smog reduction) for a number of years, but I don;t know whether they are (now) any stricter than other States, or in fact Europe. They may have over-pushed the pollutant standards (particularly NOx) to the (further) detriment of mechanical efficiency.
Concerning railways, let me just say ... OUCH! [B)]No need to shove!! I'll have you know I've been thrown out of far better threads than this!
Anyway, back at the topic.Given the engine capacity, the RPM and the air temp and pressure you can convert from ppm to g/km anyway so who cares which one they quote?
So?You can still do the calculation. In both cases you would need to sum the result over the course of the driving cycle.A peak just measures "how bad is this engine at its worst?" which isn't a bad thing to know.
Our longer-distance trains in the UK
Clifford, what's the DPF burnoff?
the standards don't even include CO2. Steve
Clifford:You will have to explain this further because it is my understanding that efficiently burned fuel has CO2 as a main component of exhaust. If CO is present, the fuel hasn't been completely burned and the engine would be less efficient. CO is a main component of wood gas that can be burned in an engine. I didn't think there was any way to burn fossil or bio fuel without creating CO2.Steve
Bored chemist. You said- "Given the engine capacity, the RPM and the air temp and pressure you can convert from ppm to g/km anyway so who cares which one they quote?" Maybe I missed the context, but the difference between ppm and g/km is that a small lightweight vehicle and a heavy overpowered vehicle can have the same ppm emission, but the actual amount of emissions are very different. The amount of emissions is what is important to air quality, and the standards don't even include CO2. Steve