Originally Posted by Danno
Shell has no issues making 91 octane fuel for Ontario Canada consumption, and it is advertised as being ethanol free.
Don't really see the need for an oxygenate unless it is some state gov't ordinance as you might find in California.
It's about meeting supply and demand. I mentioned it earlier. Where there's less overall demand for higher octane fuel, it might be possible to meet all the demand with some of the fuel sold without ethanol to bring up the octane rating.
This was an article about why 92 octane premium went away in California, but it does address the whole issue with how to deal with what you get out of refinery streams. It doesn't specifically mention ethanol, MTBE, or other octane boosters, but obviously an oxygenate like ethanol with a blending octane rating of about 105-110 AKI is going to be pretty useful to increase the overall octane rating of the fuel supply. It's also an older article and doesn't go into other things like hydrocracking which can be used to create a higher average octane rating for all gasoline produced. But the gist is about how to take all this stuff and manage to sell as much of it as possible. For the most part they don't want to sell it at a really cheap price for something other than vehicle fuel. By using ethanol they can produce more fuel that meets vehicle requirements.
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https://forum.e46fanatics.com/showp...c63a91e80&p=9046264&postcount=23
You see, when crude oil is refined into gasoline, the refinery doesn't have all that much control over what comes out. Crude oil is full of all kinds of stuff, and a refinery simply separates it, sorting all the iso-this and hepta-that in order of density. The really heavy stuff, like tar, is near the bottom, while the really light stuff, like butane, is near the top.
Somewhere in the upper ranges of the stack are the components of gasoline. There are between 10 and 15 different blend stocks, each with a different octane rating, which are mixed together to make gasoline.
The crude oil being used and little else determine the amount of each blend stock available for mixing. Generally, if you just dump all the blend stocks into a bucket, you end up with something around 88 or 89 octane. If you're selective and only mix the good stuff, you can make 92, 93 or even 95 octane. But once you take out the good stuff, you're left with crap--something like 85 octane. Then you have to leave enough good stuff in the bucket to bring this pee-water up to at least 87 octane. This limits the amount of 95-octane gas you can make. If you make 93-octane premium instead, you use up less of the high-octane stocks, allowing you to make a higher proportion of premium fuel.
In the Midwest, where an extensive customer base of good old boys in pickup trucks consume vast quantities of 87 octane, demand for premium fuel is low enough to make genuine high-octane premium.
In California, however, Lexus-driving executives suck down premium fuel like it's Evian, so 92 was the rule.