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The ‘Green’ Aviation Fuel That Would Increase Carbon Emissions (e360.yale.edu)
submitted 5 days ago by silence7@slrpnk.net to c/climate@slrpnk.net
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[-] stabby_cicada@slrpnk.net 4 points 5 days ago* (last edited 5 days ago)

Ethanol is the biggest environmental disaster in the United States. It takes two gallons of fossil fuels (counting fertilizer, transportation, and all other inputs) to make one gallon of ethanol - plus all the herbicides, pesticides, toxic fertilizer runoff, and all the other negative externalities of monocrop industrial agriculture - so a handful of Big Ag megacorps can get fat off subsidies at taxpayer expense.

51 million acres of farmland - an area the size of Nebraska - wasted turning fuel into less efficient fuel.

Of fucking course Trump and Biden found some way to make it worse.

[-] centof@lemm.ee 4 points 5 days ago* (last edited 5 days ago)

I definitely agree the corn subsidies are wasteful and over-funded. Also I'm sure your well meaning, but the myth that it takes 2 gallons to produce 1 gallon of ethanol seems like misleading oil propaganda. What is your source on that claim?

It takes two gallons of fossil fuels (counting fertilizer, transportation, and all other inputs) to make one gallon of ethanol

Even corn ethanol (one of the worst ways to make ethanol) still produces 30% more energy than the energy used to produce it. And with better production practices, it could be a lot better (and might be right now since the numbers are somewhat old) than that. That means less pollution.

Country Type Energy balance

United States Corn ethanol 1.3

Germany Biodiesel 2.5

Brazil Sugarcane ethanol 8

United States Cellulosic ethanol† 2–36

Source:https://en.wikipedia.org/wiki/Ethanol_fuel#Environment

[-] stabby_cicada@slrpnk.net 3 points 5 days ago

I will admit my two-for-one claim is at the very lowest end of estimates - possibly slightly lower than the lowest end estimate - for corn ethanol efficiency. Though it's a snappy line and easier to remember than "1.6 gallons per gallon" or whatever.

But as the Wikipedia notes at https://en.wikipedia.org/wiki/Ethanol_fuel_energy_balance :

Depending on the ethanol study you read, net energy returns vary from .7-1.5 units of ethanol per unit of fossil fuel energy consumed.

Bluntly, there's a lot of bad science around ethanol, for the obvious reason that both Big Ag and the US government are highly motivated to make corn subsidies look good and keep the money flowing.

But oil propaganda? Fucking lol. We need to phase out fossil fuels entirely. If anything, US ethanol production benefits oil companies - because ethanol is an additive to gasoline, Big Ag and Big Oil both benefit from keeping internal combustion engines on the road and slowing the transition to EVs.

So on the negative end: this 2005 study estimated corn ethanol consumed 29% more energy than it produced:

https://web.archive.org/web/20070809024158/http://petroleum.berkeley.edu/papers/Biofuels/NRRethanol.2005.pdf

And though that study is old, and the Wikipedia page on ethanol energy balance goes out of its way to claim it's been discredited (gosh, I wonder who added that content), here's an article about a 2022 study finding similarly that corn based ethanol produces at least 24% more greenhouse gases than gasoline when all the impacts - including the expansion of farmland into previously undeveloped land, funded by ethanol subsidies - are taken into account:

https://grist.org/agriculture/despite-what-you-may-think-ethanol-isnt-dead-yet/

And then there's all the other negative externalities of expanding fucking cornfields.

[-] centof@lemm.ee 2 points 5 days ago

So you mean it's not ethanol that's the problem, it's the way it's produced usually via monocrops like corn with massive subsidies. If you produced it more sustainably with a more natural permaculture like prairie grasses, wouldn't it be better than the co2 emitting gasoline status quo?

[-] humanspiral@lemmy.ca 2 points 5 days ago

Not clear. Even if no fertilizer use. Harvesting, transportation, fermentation are high co2 emmitters. Where fertilizer boosts yields, it may be a minimal contributor to net emissions.

Land owners making ethanol precursors would want high yield crops.

[-] centof@lemm.ee 3 points 5 days ago* (last edited 5 days ago)

Harvesting, transportation, fermentation are high co2 emitters

They don't have to be. They are currently because equipment and vehicles mostly run on gasoline. If the farm equipment and fuel transporters were modified to run on the ethanol it would be co2 neutral or somewhat co2 negative as the co2 harvested by the plants would be stored for later release when burning the fuel or fermenting before burning.

Heating for fermentation and distilling could also be powered by co2 neutral biomass such as crop byproducts or well managed wood forests. Usually fertilizer is less necessary with organic and permaculture growing practices since the natural diversity of plants' keeps the soil healthy and well nourished.

Land owners making ethanol precursors would want high yield crops.

Corn is actually one of the lower yield corps per acre when grown for ethanol. It averages around 350 gallons per acre. Crops such as sugar cane, sugar beets, sorghum, cassava, cattails and even natural prairie grasses all produce more than that per acre.

Corn is used so widely for ethanol in the US because of all the government subsidies keeping its price artificially low.

Well managed plant fuel is definitely better for the environment than fossil fuels. Brazil has been running most of its cars on ethanol grown from the byproducts of sugar cane production since they forced the carmakers there to adopt their engines to run it in response to the 1970s oil price shock.

[-] humanspiral@lemmy.ca 1 points 5 days ago

Ethanol is bad mostly because energy prom pv solar is over 15 times higher.

A circular corn ethanol economy Is not a solution to make it better. Just produces less surplus per acre.

this post was submitted on 27 May 2025
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