this post was submitted on 01 Jul 2024
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Isn’t summer fuel E0?
If anything, it would make sense to have gasoline with ethanol content in summer because ethanol is more knock-restistant, which you are more prone to if tempereatures are warmer.
Ethanol usage in the summer creates smog and other pollution which is why it's normally only for winter usage. Except this year, they allowed it to be used longer in an attempt to give Biden a boost in the polls
I googled a bit and the web said that ethanol does indeed burn cleaner which makes sense since there should be less contaminants and more oxygen is available. Ethanol also absorbs more heat then vapourized so there should be less heat in the combustion chamber resulting in less NOx emmissions. Do you have any sources for your claims? I would like to read about it because clearly i don‘t know everything about burning ethanol.
“Adding ethanol to gasoline is known to increase smog pollution in hot weather, but research has shown little difference between E15 and the more-widely available E10 blends.”
https://www.reuters.com/business/energy/us-epa-allows-temporary-expansion-higher-ethanol-gasoline-blend-this-summer-2024-04-19/
https://grist.org/energy/midwest-sell-ethanol-summer-smog-risk/
https://www.theverge.com/2022/4/12/23021146/biden-administration-ethanol-e15-gas-prices
This is the reason why it's typically banned during summer months.
Afaict from reading that (and one of the sources, and its source) it boils down to the fuels’ “RVP levels” (which have an impact on volatility and the amount of VOCs given off) being past a particular threshold. E10 is also past that threshold, but it has an exception that E15 doesn’t have. However, by that same measure, E15 is less volatile than E10.
The author also expressed concern about expanding corn production as a result of expanded E15 and that there haven’t been sufficient studies on the impact of E15 on the environment (particularly in the summer months). But that’s also paired with a statement saying that “consumers don’t want E15,” which detracts from the previous arguments; if true it means their impacts, if any, would be minimal.
I didn’t read every link from that page but none gave a better reason.
My takeaway is that it sounds like we don’t have any data showing that E15 is worse than E10, so the obvious move is to actually start funding those studies.
I also found https://foe.org/blog/2012-05-understanding-e15/ which is very anti-E15; however I wasn’t able to verify their claims because none of the linked articles loaded for me.
I mean the proof is in the pudding with this one as you must also ask yourself why E15 is banned during summer months in the first place. If you can answer that question you'll likely find the information you're looking for.
It isn’t.
I did. And I shared that in my comment above.
Your source doesn’t share any data on the topic, even just as a summary, but it links to summertime smog, which links to “smog-causing pollutants”, which says:
The article’s justification for why E15 isn’t legally permitted is that there’s a law against it, which is circular logic. From the environmental protection perspective, it doesn’t sound like there is data suggesting that E15 on its own is worse for the environment than E10. If the only argument is a legal one, it’s not a good argument.
I did, and I shared that answer in my comment above, too - but it’s not the answer you seem to think it is.
Knock resistance is related to octane and not ethanol content directly I thought
You are correct. Ethanol does have a higher octane rating though so a blend of gas and ethanol will have a higher octane rating and hence knock resistance.
summer fuel?
There’s a difference between summer and winter fuel for gasoline engines in some areas. It’s usually to do with smog restrictions.
The same octane can be reached with different blends of hydrocarbons. So instead of just ‘pure’ gasoline to hit a desired octane, refineries can mix together higher and lower octane fuels to reach the same overall octane rating. This increases the amount of refinery products that can be used to blend gasoline, so it can be made more cheaply. The trade off is that it’s less pure, and most importantly for this comment - that some components of of these cheaper blends may evaporate more readily, leading to smog.
In summer, when it’s warmer, some areas mandate gasoline must meet certain standards for evaporation. In winter, those standards are decreased, because it’s cooler.
Ethanol has a relatively low evaporation point. I don’t know the specifics of the commenter’s location, but I could see ‘summer gas’ having no ethanol to meet these standards.
More info: The Vapor Rub: Summer versus Winter Gasoline Explained — Car and Driver
that's wild. is this relatively new? I used to live in the Great White North and I've only been down in Florida for 10 years
I must confess - aside from knowing there was a difference, I didn’t really know what the difference was until a few online searches yesterday.
The understanding I have is that winter/summer gas programs began in the late 1980’s.
My supposition is that they have been handled seamlessly to the point that unless you are involved in regulation or the industry, it’s relatively inconsequential to most folks. I imagine knowledge of the program’s existence is probably one of those things that people sorta ignore unless it randomly becomes a topic of conversation. (Like any number of random regulations that impact our daily lives that we just don’t think about most of the time.)
I did always wonder how they made up for the changing energy density due to temperature
I am not sure but I suppose it's the opposite of what we have here commonly called winter fuel, which I think has some additives to help engines run better in low temperature conditions.
Are you thinking of diesel? Winter diesel has additives to stop it thickening in the cold weather
Yes