MartinC wrote:I weary of this. You've selected one piece of research you like. The prologue selectively quotes the perceived advantages of diesels but misses one of the main ones. The paper quotes the source of your favourite "100 times" quote as a test of some "selected" diesel engines. The only point this is driving home is that you can cherry pick your way to any conclusion you like.
It was only selected insomuch as as it was the first one on the list, there are many many more. There is no need for cherry picking the evidence is damning. How about producing some peer reviewed articles which suggest petrol vs diesel is 6 of one, half a dozen of the other WRT toxic emissions?
Lets re-iterate the well accepted facts. Diesels produce less exhaust than petrol engines. Diesel exhaust contains higher concentrations of some pollutants than petrol exhaust but both produce the same pollutants.
Diesels so not produce less exhaust, simply incorrect, size for size a diesel engine prduces considerably more exhaust gas.
I too would like to see particulate filters tested and older vehicles of any description that don't meet current emission standards encouraged into retirement. I think the current VED banding is a nonsense and should be changed.
100% agree
NO2 emission in the UK has been a growing problem from way before diesels became popular - it's related to the growth in traffic and we need to do something about this too.
This is incorrect, the 3 way catalyst as used on any modern spark ignition engine (petrol, lpg, cng) since the 1990's deals with the NO2 emissions very efficiently, the problem we have now really is down the increased number of diesels which have emission control equipment which blatantly doesn't work.
What I don't share is a simplistic notion that a). we can just magic diesels away and b). everything will be much better if we do.
It's a difficult situation we find ourselves in for sure and magic isn't going to solve it. What we could do is tighten up the MOT emission test and get rid of the idiotic VED banding for older vehicles.
How about creating some new MOT standards that stipulate that older vehicles (regardless of fuel type) must not emit more than say 20% above the perscribed limits for PM, NO2, HC etc? That would give owners of these rattly old polluters a choice: pay for some repairs or get it scrapped. Such a measure would rid us of a usefull % of the street level poison. No doubt some would claim it was unfair, some would even claim to be victims of persecution
What do we think? Would no more than 20% above the standards when the vehicle was sold be reasonable?
I can remember the 70's and 80's when the big problem of the day was lead in petrol. We solved this by putting benzene, the most carcinogenic substance known to man, in petrol. Around the same time we got our knickers in a twist about emissions from petrol engines and the solution was catalytic converters, shame that they're as much use as a chocolate teapot in the UK. After that we decided that CO2 emissions were the big thing and encouraged people to use diesels instead (and we know what you think about that). Now it's NO2 (or is it particulates) that we must get excited about and construct some half buttocked solution that will allow us to carry on with the same unsustainable behaviour.
This is basically an urban myth. Benzene was not added to petrol to replace the lead. Benzene was not added at all, it is a natrual component of crude at circa 4%. I think the myth originates from motoring forums from people who lament the passing of good old 5 star. The aromatic content (including benzene) did increase somewhat post lead because the fuel needed to be more highly refined to resore its octane rating (one of the functions of lead was to boost the octane rating). Contary to the urban myth, exhaust emissions of benzene actually decreased once lead had been removed from the fuel due the the effectiveness of the 3 way catalyst at turning the hydrocarbons in to CO2 and H20. Evaporative emissions were controlled by the carbon cannister.
Any references for your claim that the 3-way catalyst is
as much use as a chocolate teapot in the UK
?????
Air quality in towns is always going to be a problem until you reduce the traffic. It's an enclosed space with too many emissions. If you want an analogy it's this: put your car in the garage and leave the engine running, close the door from the inside, you've got a big problem irrespective of whether it's petrol, diesel, lpg or a hybrid.
Actually the petrol or the LPG car would kill you quickest due to the CO, which diesels don't produce, not that this has any real relevance to the issues in hand.
