Presumed you really meant:
Interesting.
When it comes to CO2 emissions the elephant in the room is that the volume of crude oil required to make a gallon of petrol or a gallon of diesel is very different.
It is - and it was 1979-80 that it jumped to > £1/gal (I remember the whining).
Sorry, I was thinking in terms of the energy it takes to produce a litre of Petrol where fractions are cracked to produce aromatics and other higher octane components, where diesel doesn't have these secondary consuming processes.
I did hear a figure many years ago that it takes a pint of crude to heat crack fractions to make a blend that is RON 95.
If only duty was put on that pint, or even used to consider the bigger picture of CO2 per mile!
Except that it's different bits of the barrel of crude that go into either. You can't turn a barrel into or .
In part I will agree with you, but as far as I know, even with the various fractions separated, you still can't blend petrol to get sufficient octane to be useful without further cracking and processing.
Diesel can however be used direct from the refinery with just some small quantities of lubrication and other additives.
In fact you sort of CAN turn a barrel of oil into either diesel or petrol. The name of the game is catalytic 'cracking' (these days thermal cracking) and you will hear talk of 'crack ratios'. Whether you break the crude up into longer (diesel) or shorter (petrol) chain hydrocarbons is I think a function of the exact nature of the catalysts composition.
Its a long time ago to A level chemistry - so maybe an organic chemist will step in with more info.
There isn't a huge amount added to petrol either these days, butr both diesel and petrol will always have additives when bought at teh pump
The residue is not wasted (ie still burned) so makes no difference at all.
Converted hydrocarbons are needed to supplement petrol. They take a lot of energy to produce, although now less so with catalytic cracking.
The heat needed to produce these is wasted, as is the oil providing this heat.
I haven't been able to find much information on blending and thermal losses / wastage. I guess they are regarded as being commercially sensitive.
Petrol itself is 'converted hydrocarbons'.
Cat cracking has been around since my A level chemistry in the 60s...
WEll wasted is a moot point,. The carbon is burnt off the catalysts to keep them hot enough to do the cracking
Actually I think its more that they are highly specialised well known by all oil companies and ultimately boring.
That also doesn't explain how over the past decade or two diesel compression ratios have generally decreased.
Perhaps diminishing returns?
Nox noise and Turbochargers
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