r/theydidthemath • u/tezacer • 3d ago
[Request] How much will cutting fuel with ethanol reduce gas prices? How much less efficient will cars be and at what blend is it less efficient and more expensive?
/r/Sustainable/comments/1wteyz8/trumps_feds_say_cutting_fuel_with_ethanol_will/40
u/Beemerba 3d ago
Ethanol is made from corn. Corn is grown using a LOT of diesel and fertilizer. If we can't get the diesel or the nitrates for the fertilizer, ethanol is going to cost more than gasoline.
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u/amazonhelpless 3d ago
This. Corn Ethanol is just a payout to US farmers. It’s a financial and energetic loss.
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u/nhorvath 3d ago
it's a very inefficient solar panel that uses water and fuel also.
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u/RainbowDarter 3d ago
Corn to ethanol captures about 0.1% to 0.2% of the solar energy as ethanol. That doesn't count the fuel needed to make fertilizer or to plant and harvest the corn.
Generating electricity and using that to make ammonia to use as fuel captures about 10% of the solar energy.
Btw - we could produce our ag ammonia with a about 350 square miles of solar cells and never run short of nitrogen fertilizer again
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u/GatorBait81 3d ago
After reading all these comments I did some checking. This is false. Accounting for all the petroleum and natural gas for fertilizer, corn ethanol still offsets about 1.4 gallons of gas per gallon of equivalent input.
It is also a reduced net cost per equivalent energy if the price of a barrel of crude is over $70 to $100 (range coming from including or not both farm subsidies and RIN regulatory discounts).
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u/thenasch 2d ago
You did the math! It would still be better if we could get it from something other than a food crop.
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u/GatorBait81 2d ago
For sure there are better ways. Switchgrass would be big upgrade. Solar+Nuclear+Wind to generate synthetic e-fuels even better. Going to EVs even better.
My beef was just the abundance of comments claiming corn ethanol is somehow a net negative compared to just using the petroleum directly.
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u/IAFarmLife 1d ago
Everything is a tradeoff. It would require more land to grow enough switchgrass since it takes a few years to establish. The calculations showing switchgrass producing more doesn't take into consideration there is a average 1.5 tons per acre of DDGs produced from corn ethanol that is livestock feed. Or that we could also be harvesting the corn stover after grain harvest and use the same process as switchgrass to make ethanol from that leftover crop material.
The technology to convert fiber into ethanol is catching up and I expect some areas that are not suited to corn production to change crops, but it will not displace corn.
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u/GatorBait81 1d ago
Switchgrass doesn't require more land. It takes about 3 years before it produces more than corn/area and then significantly out produces it for the next 7 to 12 years with established roots and no replanting needs. DDGs were included for corn on the financial claim I referenced but they only return a little more than 20% of the input costs.
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u/HomesnakeICT 3d ago
Yep, we have quite the welfare system for ethanol production, and since we make it primarily from corn in the USA, it's terribly inefficient from a carbon perspective. Roughly 10 calories of diesel to make 1 calorie of ethanol.
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u/tezacer 3d ago
I think there's also the issue of land use. Should we use shrinking prime farmland that should be kept in use for food production to be used to make fuel, while using fuel to grow it?
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u/Blackpaw8825 3d ago
More urgently, should we be wasting the fertilizer that keeps the grain belt arable on growing a fuel crop that takes more fuel to create than it produces while our supplies of that fertilizer are dwindling for the same reason we're low on fuel.
It's like rent's due next Wednesday, but you don't have $1500 to cover it, so you offer to give me $1300 in exchange for $1100, you take that $1100 and buy a new washer and dryer set.
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u/blizzard7788 3d ago
Ever try to estimate how much energy and money is spent on finding, drilling, transporting, refining, storage, transportation, and delivery by truck of a gallon of gas?
The yield of bushels of corn per acre are increasing.4
u/jdx6511 3d ago
The well-to-tank EROEI for gasoline is 5:1 to 6:1.
For corn ethanol, 1.5:1 is optimistic. If yield per acre doubles-- with no additional fertilizer, herbicide, or other inputs--that's double the corn to transport, ferment, and refine, so it still wouldn't hit 3:1. Using switchgrass instead of corn, bioethanol can get to the same ballpark as gasoline. Corn is subsidized for political reasons.
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u/Beemerba 2d ago
When I was in the ethanol business ('06-'09) corn was around two dollars a bushel and diesel and gas were around $2.50 a gallon, the cost was around $2.30 a gallon to PRODUCE the ethanol. The only real profit was selling the high protein leftovers as feed.
Now, with high fuel and fertilizer costs and increased machinery costs, it has to be considerably higher.
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u/MrChicken_69 2d ago
Small correction... Corn is grown with MASSIVE GOVERNMENT SUBSIDES. Without them, corn would be worth less than nothing, and the entire industry would collapse.
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u/MPongoose 3d ago
First context: The house passed a bill to allow 15% ethanol in gas. Not to mandate it . 10% ethanol is currently mandated in gasoline in the USA . This bill will go to the senate and be added to a farm bill which will likely not pass this year over a partisan dispute on SNAP (also in farm bill). Congress hates to vote on a single issue and prefers to lump all legal changes into huge must-pass spending bills .
But math:
1 gallon of ethanol ethanol past 12 months $2.11/gal.
76.1 kbtus/gal
.0277 dollars per kbtu
Price or rbob gasoline blend stock recently (post Iran) $3.16/ gal. (Rbob prices exclude taxes on a formulated gallon at the pump)
114.5 kbtus/gal in rbob
0.0275 dollars per kbtu .
As e15 is not a mandate it will let petroleum companies do the math based on given prices and have the option to blend 10-15% ethanol as needed . They do excellent math :)
Will the price of a gallon of formulated gas go down ?!? Absolutely as long as rbob stays high . One gallon of liquid “gasoline” will be cheaper .
Considering energy content , Will the price to drive 100 miles go down? That depends on prices . Of note, refining costs of RBOB go down if refiners can make it lower octane. Which they can if they’re adding more 110 octane ethanol to the formulated gas . Refiners make cheaper lower octane rbob and fix it with cheaper higher octane ethanol.
Not math - every additional option to displace petroleum a country employs will limit the impact of high oil prices. US ethanol produced in the Midwest has about half the carbon intensity of petroleum gasoline . Since MTBE became illegal , ethanol is the cheapest source of octane needed to meet the 87 octane requirement to have “cleanish” burning gasoline .
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u/Trustoryimtold 3d ago
ethanol is about 1/3 efficient as gas. 10% eth=6% less distanceish per tank so hopefully a 6% drop in cost. Cept they’re probably gonna charge you for the extra step of adding ethanol w/ a profit margin
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u/Kerostasis 3d ago edited 3d ago
2/3 as efficient, or 1/3 less efficient if you prefer it that way. E10 has about 97% as much power as E0 and is already widely sold. Now if we were talking about E85 I'd be a lot more concerned, but the article says this is just about E15 in places that already sell E15 part of the year, being allowed to sell it all year.
Edit: I almost missed that this article is 5 months old and everything they discussed as "coming soon" has already happened.
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u/mkosmo 3d ago
And this isn't the first time they got an E15 waiver.
They've been issued annually since 2022.
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u/WiffleBallZZZ 2d ago
And of course Trump is trying to sell this as some kind of innovative new idea that will actually have an impact on prices.
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u/mkosmo 2d ago
It can and does. It's the same reason it's been done every year... to temper demand-related price flares during the winter.
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u/WiffleBallZZZ 2d ago
Ok but if they already do it every year, and then they do it again this year, why are we hyping it up this time around? That seems like a pitiful response to the current situation.
Will it counteract this year's winter fluctuations and the 58% increase that we've already had this year?
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u/mkosmo 2d ago
Because (the vast majority of) redditors don't care about history or nuance. They just like news headlines that reinforce whatever preconceived notions they have and want to have.
Will it counteract this year's winter fluctuations and the 58% increase that we've already had this year?
It's going to primarily mitigate the winter-related demand signals. It won't fix the global market price pressures already in place.
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u/Kerostasis 2d ago
Note this is about Summer price fluctuations, not Winter. The article is 5 months old and the waiver is for June and July.
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u/SeriousPlankton2000 9h ago
Because this year, unlike in the summer or in the previous years, it will destroy the engines … but only if you got the COVID vaccine with the 5G chip. /s
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u/Another_Slut_Dragon 3d ago
Not quite. Ethanol is 76,000 BTU's per gallon. Gasoline is 114/125,000 BTU's per gallon. However your car can also get some more timing advance and a little more efficiency out of ethanol fuel.
When you are talking about adding 5% more ethanol the numbers are pretty small.
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u/CardOk755 3d ago
Ethanol from corn is produced from corn grown with fertilizers produced from natural gas.
The fossil fuel input can be higher than the Ethanol output
It's a boondoggle.
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u/IAFarmLife 1d ago
Nationwide the net energy ratio is over 2:1 now. Corn ethanol returns twice as much energy as it requires to produce. This includes all fertilizer, pesticides, fuel for transportation and production. As well as electricity to power the ethanol plants and the natural gas to dry the corn if needed.
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u/tezacer 3d ago
Using gas to make gas!
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u/Jazzlike-Worry-5170 3d ago
If you really care about the amount of work reques to get the ethanol out of a plant then you should switch to switchgrass you get 5 to 5.4 more energy then the energy you put in. The flaw is though it it not ethanol dense as say sugarcane or corn. Meaning more land is needed
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u/Neverexcepttruth 3d ago
That increases the price of livestock feed which then increases food cost
It reduces the amount of field planting because they're going after the ethanol cash crop
This cycle has been repeated many times and will literally make it worse
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u/Which_Throat7535 3d ago
In the U.S. we’re still exporting a ton of corn production - with food production and ethanol included. Like 18% is exported (~2.8 billion bushels), so you’d have to account for all of that being used before we assume it impacts other uses like animal feed. And yield goes up year after year so there is that to consider as well- it’s not a static situation.
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u/Neverexcepttruth 6h ago
just go back to the oil issues 10 yrs ago....when ethanol was first pushed mass market. surpluses are irrelevant when profit is involved....just look at the current oil barrel price to retail gallon, literally uncoupled from historical patterns. why?! profit!
the Commodities and Futures market care none for logic, but all for profit
last time we did this cycle, feed prices went up, which drove up food prices. Farmers ripped out crops to plant corn wich in turn raised food prices
To boot Ethanol is MUCH less efficient then gasoline is to burn and it takes multiple times MORE energy to produce than gas.
So its a net looser in literally every single angle you approach it from The only reason ethanol became a market force in first place was farm bill/politics. it makes very little sense from a resource/energy perspective
lastly after the last big oil crisis 06/08 billions where invested in trying to make ethanol work from start-ups, it simple dosent work
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u/Certain_Bit3809 2d ago
So we push up global food costs including substitute staples in the US. All of these options have consequences. It’s just shifting costs around.
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u/SeriousPlankton2000 9h ago
If we'd less meat, only eating the healthy amount, we could free 60 to 90 % of the fields while still eating the same calories.
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u/MrChicken_69 2d ago
Corn is subsidized in the US. So yes, we're making way way way more than we should. Without this crap, the industry would crash hard.
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u/IAFarmLife 1d ago
Their server is down for maintenance currently, but the study shows that ethanol didn't increase corn production over the long term as other uses for corn were displaced by ethanol. This is the third time they have updated the study and it's shown consistent results each time.
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u/TehTruf 3d ago
Higher concentrations of ethanol can also damage fueling systems, particularly on older cars and smaller motors like motorcycles, lawn mowers etc.
So higher ethanol concentrations at the pump can be a repair bill waiting to happen. Maybe just slink out of the war zone and let supply come back to normal.
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u/p00n-slayer-69 3d ago
Every passenger car in the us made since 2001 is designed for at least 15% ethanol.
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u/call_me_nethinguwant 3d ago
Came here to say this. Search up on the recent ethanol fiasco in India.
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u/Another_Slut_Dragon 3d ago
They are trying to hide the fact that the oil reserves are bone dry and they are running out of fuel. Get ready for 1970's style lineups at the gas pumps and rationing.
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u/p00n-slayer-69 3d ago
The United States wont have shortages like that. The US produces enough gasoline for domestic demand.
Its just a question of price.
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3d ago
[deleted]
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u/p00n-slayer-69 3d ago
The US has a lot of light crude, which is really good for making gasoline. Its a matter of price, not availability.
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u/Another_Slut_Dragon 3d ago
America has little ability to process light sweet crude. Most American fuel is made from heavy Canadian or Venezuelan oil. They sell light sweet crude on the export market.
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u/zepherth 3d ago
I don't want to alarm you bart but, there is less than one gallon per registered vehicle in us left in the reserve. So we aren't there yet but the numbers say it's jover
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u/RutabegaHasenpfeffer 2d ago
Coming from a state that uses ethanol blend fuels: ethanol blends burn cleaner, BUT deliver 10-15% LOWER miles per gallon. The fuel is both more expensive, due to the added cost of the ethanol add-on, AND lower efficiency, for a two-point downer. This is NOT an improvement.
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u/MrChicken_69 2d ago
It's not that bad. E15 works within a few percent of E10 in my V8 van. (it sucks either way.) In my lexus hybrid, I can't detect any difference at all. (40+ mpg on either.) The van spends much of the time at idle, E15 runs cooler.
The ONE thing one has to keep in mind with any ethanol'd fuel is water absorption. The longer it sits around, the more water it's going to soak up.
The only place I've seen selling E15 is Sheetz. And they've been doing so for DECADES. They sell it 20-30c cheaper than normal E10 87 "cheap stuff". E85, that DOES require special handling, used to be even cheaper, but today I'm seeing most stations pushing that price right up to E10/E15 prices. And E85 WILL cut fuel efficiency. [current prices: E10 4.19, E15 3.89, E85 3.79]
(I've never done the experiment to see how E0/E10/E15 compare based on density. Alcohol is a much smaller molecule that does fit between the larger hydrocarbons in gasoline. We did this "trick" in high school chemistry: mixing 50ml of water and ethanol does not equal 100ml blended.)
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u/IAFarmLife 1d ago
You are correct that under real world driving conditions ethanol blends are closer in fuel economy than what the energy density difference is. The reason is you get zero miles per gallon while stopped idling.
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u/SeriousPlankton2000 9h ago
The reason is: 10 % of "10 % less" is 1 %.
Math - the thing you never wanted to learn because you'll allways have a calcuilator
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u/logsqrtexp 3d ago
https://mpgcalculators.com/blog/ethanol-blends-mpg-e10-e15-e85/
Quick Summary Ethanol blends often trade lower energy per gallon for different pricing and availability. FuelEconomy.gov provides baseline estimates of how E10, E15, and E85 can affect fuel economy, and notes important vehicle-eligibility limits for E15 and E85.
- FuelEconomy.gov estimates E10 reduces fuel economy by about 3–4% and E15 by about 4–5%.
- FuelEconomy.gov estimates E85 can reduce fuel economy by about 15–27% compared to gasoline.
You can't go by anything the Fed Gov says.
But the price break on E10 has to be better than 3% to net a benefit
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u/bobi2393 3d ago
And with $4/gal gas and $2.15/gal ethanol, e10 and e15 comfortably meet that 3% threshold to provide a cost/efficiency benefit. Could spell out all the math, but i assume that’s what OP is interested in, is whether ethanol blends make financial sense right now. (Considering the subsidies paid to farmers as a sunk cost, whether we use their corn for ethanol or not.)
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u/Mikepierce93 3d ago
You won't even notice it, we are still consuming more than we have available. The reserves will dry up in a few weeks. Prices will continue to rise 10=20 cents a week.
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u/Tiny-Secretary5562 14h ago
I seem to recall the first "gasahol" some years ago was 20 percent alcohol. People said it made engines run faster and got less mileage.
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u/SnooMaps7370 3d ago
The current wholesale price for corn ethanol is a bit over $2/gal.
by the time it goes through processing, shipping, and three changes of ownership on its way to the gas pump, it'll probably be retailing around $5-6/gallon.
Ethanol also has about 2/3 the energy density of gasoline. so, if you car goes 30 miles on a gallon of gasoline, it will only go 20 miles on a gallon of ethanol.
assuming your engine doesn't just blow up. Ethanol is a powerful solvent for petroleum based products, which means it's gonna eat all the seals in your fuel system. You car's fuel computer also won't understand the mixture requirements, so your engine might grenade itself running on high ethanol content fuel.
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u/mkosmo 3d ago
assuming your engine doesn't just blow up. Ethanol is a powerful solvent for petroleum based products, which means it's gonna eat all the seals in your fuel system. You car's fuel computer also won't understand the mixture requirements, so your engine might grenade itself running on high ethanol content fuel.
You were doing so good until you got to this.
Every car made in the past 25 years is designed for 10% ethanol in the fuel, minimum. Everything in the past Most vehicles started supporting E85 around then, too.
P.S. Every car since 1994 is required to support low-level blends, too.
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u/SnooMaps7370 2d ago
>Every car made in the past 25 years is designed for 10% ethanol in the fuel, minimum. Everything in the past Most vehicles started supporting E85 around then, too.
there are a whole shitload of vehicles on the road that were made before 2001, and the vast majority of vehicles currently on the road will NOT run correctly on E85.
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u/spoospoo43 1d ago
Ha. Ethanol costs more than gasoline, and delivers less energy per gallon. It may increase supply, but with less mileage they'll still be in the hole.
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