Hacker News Reader

Comment by hatsunearu | Hacker News Reader

Ethanol also is used as an octane booster. I'd rather take Ethanol than MTBE or TEL.

That's a poor justification for the current regulatory regime in which ethanol in gas is mandated. If MTBE or TEL then they should be banned. If regular gasoline doesn't have enough octane, it should be up to the market to figure out which octane booster should be used, rather than the government enforcing use of ethanol by decree.

That’s also how we ended up with leaded gasoline.

The fact that the current regulatory regime hasn't forced the use of an octane booster that is acutely toxic is more of a case of a broken clock being right twice a day than it being good policy. I would even argue that in this case, the broken clock isn't even "right". As the OP points out, use of ethanol has negative consequences as well, and the fact that its use is mandated basically gets rid of any incentive to come up with a better octane booster.

Ok, but one broken clock is easier to manage than a dozen broken clocks that are also potentially malevolent. At least all cars are tuned for the same type of fuel, and it would theoretically be easier to migrate all infrastructure from one formula to another as we did with lead.

How would auto manufacturers manage their cars' fuel systems if every station could potentially have a different octane booster? How do all those cars switch over to an entirely different formula when a bunch of those octane boosters are found to have issues?

Personally, I think the industry needs an R&D consortium to look into better technologies that all shareholders can use. Federal input and regulation, but the companies are free to work together to find better solutions for the environment and our health.

This should be the highest rated response to the parent because it's overwhelmingly used as a low octane fuel booster additive, not a fuel.

If you have 85 gasoline and need to get it to 87, you blend it with an appropriate quantity of ethanol (octane rating 108.6, thanks for the correction).

Reference: https://afdc.energy.gov/fuels/ethanol_fuel_basics.html

Yeah, gas producers like it as cheap octane booster.

Actually most of the time it costs more for oil companies to purchase the ethanol than it would for them to use smother burning hydrocarbons which they already have access to in larger quantities.

pure ethanol according to wikipedia has an octane rating of 108 on the scale that's normally referred to. 100 is the octane of a particular isomer of the hydrocarbon C8H18 which is called... octane!

https://en.wikipedia.org/wiki/Octane_rating#Examples

and for people not familiar with the subject, the purpose of an octane booster is to make your fuel less explosive (even though the point of your fuel is to be exploded to release it's energy) The problem with low octane fuels is not that they have lower energy, but that when you compress them they can explode prematurely (before you're ready to collect the energy) and compressing them is a way to get more energy out of an engine. Ethanol is less explodey, and so is tetraethyl lead.

Molecular models are like tinkertoys.

Carbons are the little black spheres with 4 equidistant holes, and hydrogens are the smaller white ones with a single hole.

And you've got all the little somewhat-flexible rods to act as chemical bonds and connect the different carbon and hydrogen atoms in any combination you like.

Octane is a generic name for most any combination you can legitimately make out of C8H18. Any of these is referred to as an octane isomer.

If you put all 8 carbons in a straight row and "saturate" the remaing holes with the 18 hydrogens, this straight-chain form in particular is referred to as Octane proper, or more descriptively to avoid confusion, normal-octane since it is a straight-chain isomer.

This normal- or n-octane is not the stuff that burns with a very good antiknock rating at all.

The one particular branched-chain C8H18 isomer having the proper name 2,2,4-trimethylpentane is the one that serves as a calibration fluid for laboratory antinock determination. Even though there are many other branched-chain C8H18 isomers possible, this one is the most commonly obtainable and carries the generic name "Iso-octane".

Runs smooth as butter.

Goes well with vintage MTBE.

Reply on news.ycombinator.com