Post by Roland Perry Post by firstname.lastname@example.org Post by email@example.com
While I'll agree something needs to be done about the pollution in
London, essentially outlawing cars that that will affect the less
well off is not the way to do it. The millionaire in his 8mpg 2016
Lambo isn't going to be
affected but the single mum in a low paid job (for example) driving a
2000 micra will be. Its disgusting.
Still, Labour have been showing their disdain for the working classes for
years so I guess this shouldn't come as a surprise.
If the pollution is reduced then the residents, even the poor ones, will be
better off health-wise.
Anyway, isn't the tax on diesels only? People can always get an old
petrol-engined car as I have.
The problem with that is they tend to be gas guzzlers. I swapped my 2001
petrol car for a 2005 diesel last year and literally doubled the MPG
(same size engine and a slightly bigger vehicle).
Not an entirely fare comparison. Diesel is denser than petrol, so a gallon
of diesel will emit more CO2 than a gallon of petrol. There's also the
issue that Diesel engines produce significantly more of the types of
emissions that are directly harmful to human health in an urban
environment, namely particulates and NOx. Diesel engines burn with a
diffusion flame in excess air while petrol engines burn with a premixed
flame in roughly stoichiometric air/fuel conditions. The diffusion flame
gives rise to the particulates problem due to incomplete combustion. If you
have an exhaust gas without free oxygen, a simple catalytic converter will
reduce NOx to molecular nitrogen and molecular oxygen (ie the stuff in
regular air). If you use the same catalyst with excess oxygen (as is
present in diesel exhaust), the oxidizing environment will drive the
chemistry the other way and potentially increase rather than reduce (in
both senses) the NOx. There are other chemical pathways that can be used to
reduce the NOx emissions from a Diesel engine, generally involving urea
(the industry has adopted the name ad blue because marketing people think
the word "urea" might be unpopular).
There is the other issue that between 2001 and 2005 engine technology for
both petrol and Diesel engines improved, so it's not really a like for like
comparison in terms of technology level.