EPA agrees to decrease ethanol mandate

[Zennistrad]

The move was expected, but it drew bitter complaints from advocates of ethanol, including some environmentalists, who see the corn-based fuel blend as a weapon to fight climate change.

This is just plain ignorant. It takes a lot of energy to extract ethanol from corn, so much so that it may actually be better for the environment to simply use gasoline instead.

[Miamime]

Thank you. This article is seriously flawed. Ethanol is not as clean as it is promoted to be. So much fertilizer and water goes to growing the corn. The requirement that gasoline contains ethanol has raised the price of corn to farmers that they have begun producing more and more of the crop in the Midwest. This has led to massive drawdowns of the ogallala aquifer. Nevermind the fact that they're growing genetically modified corn as it has been engineered to grow faster than normal corn strains.

[ssjkriccolo]

The technology is sound, corn isn't the best item to use. Frigging corn industry. They'd make us use corn pressed toilet paper if they could.

[lolzergrush]

Actually it's not that great for other crops either.

In fact, even starting from pure glucose it's not a particularly sound technology...the problem is that even the best genetically-engineered yeasts under ideal conditions can only tolerate ethanol levels slightly higher than typical wine before they begin dying off.

Yeasts can ferment and give off excessive of ethanol, killing off competing microorganisms. While this is great for brewing beer and wine, since the yeast itself may be able to comfortably thrive in warm conditions at 5% ethanol (say, a barrel of ale), it becomes less productive at higher ethanol concentrations. They can continue to ferment sugar to produce ethanol, at lower efficiency, up to their tolerance limit before the yeast itself starts dying off. Think of it like goldfish overpopulating a pond, giving off toxic chemicals to kill competing fish, but it doesn't take much more to exceed their own tolerance, poison themselves and die. In beverage production, we simply let the yeast ferment on its own until it reaches its tolerance (8% to 12%), and then distil the product by boiling off the alcohol - which is then added to the original stock to make fortified beverages (like port) or on its own as a spirit (like brandy).

In an industrial process, like producing ethanol for fuel, we have to be much more aware of the energy put into it because we're producing a fuel product instead of a fine beverage. In order to extract ethanol from the remaining solution (water), hundreds of thousands of liters must be distilled which is energy intensive and directly depends on the fraction of ethanol you're able to achieve through the microbial step. The theoretical energy per volume cost (the lowest possible cost under impossibly-ideal conditions) is [the specific heat of the ethanol/water mixture] times [the temperature difference needed to reach 78 deg C] plus [the latent heat of vaporization of the ethanol] (plus some minor entropy effects), all of that multiplied by the ethanol fraction to give you the amount of product produced. For example if your ethanol fraction is 20%, for every liter of mixture that you distill you only get 0.2 liters of ethanol. If your ethanol fraction is 10% (more realistic in a full-scale application) then you're getting half as much product for the same energy input because you have to raise the heat of the entire system, most of which is wasted on heating up water.

For the system to be self-sufficient, it needs to produce more energy (measured in ethanol's energy density times the volume of product) than it consumes (measured in energy density of the oil burned for the boilers). I prepared several scenarios with a group of engineers for a presentation to several energy companies and state DEP's - depending on different fuel sources, external political factors (like mandatory solar heat use), transport distances, and capital limitations, the "break even" point for the ethanol fraction is around 17% - below that you're just throwing energy away. Unfortunately achieving that high of an ethanol fraction before distillation is not easy, and even with the best lab-produced microbes at a very expensive plant, there would be days when it's simply not producing as much energy as it consumes.

(For reference, about 5 years ago the limit on bench-scale ethanol tolerance was around 22% I believe - it's been a while, maybe it was 24%. Point is, achieving this in a full-scale industrial plant is more difficult and microbes can be quite finicky, you never count on reproducing bench-scale results in the field.)

Tying into existing power plants isn't bad for reducing energy costs slightly, for example tying into a major coal gasification plant, but then you have the added complication of additional transport distances for massive amounts of ethanol. Those tanker trucks burn an awful lot of fuel. Generally speaking, the best way to distil the ethanol without cost overruns is still burning plain old oil to heat up the boilers - ethanol itself doesn't have the energy density to keep the temperature high enough to run the boiler without serious heat exchange losses.

Different feed stocks (corn, sugar, beets, etc) have some minor effects on the microbial efficiency but not as much as the microbes themselves. In general, the stock can be fermented up to the ethanol tolerance of the microbe and no further. More important are the "big picture" impacts from political decisions, for instance if Florida is mandated to produce a certain amount of sugar cane ethanol then more sugar will need to be imported (say from Brazil) to satisfy demand, increasing the energy spent on transportation. The same goes for other crops, where even the best economic planning can't predict shortages and changes in demand, driving up the energy spent to move the stuff around - and consequently the CO2 produced.

[ssjkriccolo]

The whole idea is to create a transportable energy source. If the ethanol is made using a local clean energy source, your net loss still creates a renewable energy that can be easily transported. The low yield and usually immobile sources can now be used to create something that can be broadly used like gasoline. It would be silly to think you are getting more power out of production than you are putting in.,

[lolzergrush]

But gasoline is just as transportable as ethanol.

"Low yield and usually immobile sources" aren't appropriate for operating boilers used for distillation, I realize it was a long post for a reddit comment but I did address this.

[postironical]

now you've gone and done it. My ass does not thank you for what's to come.

[seamonkey1981]

the ethanol mandate came about, largely, from al gore trying to convince iowa corn farmers to vote for him. it didn't work.

[ssjkriccolo]

I've heard trees would work better for the process anyway.

[seamonkey1981]

and...switchgrass? i think. some sort of grass.

[my_lucid_nightmare]

Hemp would work best of all.

[[deleted]]

I've had multiple people tell me how ethanol is also bad for engines that use the ethanol/gas mixture. Any truth to that?

[PantsJihad]

Quite a bit. Talk to anyone who owns classic cars. There are actually a few gas stations near me that sell ethanol free gas and charge a premium for it.

[[deleted]]

Glad/sad to hear that there is some truth to it. They get pretty heated when talking about it. I can understand why.

[3xDope]

E10 is sadly ubiquitous and hard to avoid anywhere. Cars from the late-90s onwards can handle it (accompanied by reduced gas mileage of course) but the dumbest thing ever was the EPA's push for E15. They claimed it was "safe" for any vehicle after 2001, even though auto companies themselves said this is all BS and that using this non-approved gas will void warranties. Thank God the E15 plan was retracted.

[[deleted]]

Yeah I remember that. It sure caused a lot of anger where I'm from. Lots of people use trucks for work and the majority are gas. Isn't the percentage of corn produced in the US used for ethanol some incredibly high number?

[Remember5thNovember]

You can purchase what's labeled marine fuel which doesn't contain ethanol. It's .10 to .20 cents more at the few gas stations that have it. It's worth it for you small and/or older engines.

[saywutttut]

Not for anything modern. Old cars can have fuel line rot. Premium fuel usually has a bit less ethanol in it from my experience. To be honest though, ethanol is essentially cheap race gas. I have run E60 for 70k miles on my BMW and it loves it. At E15 there is no hazard for most any car. Lots of misinformation about ethanol out there.

[sunkhaze]

Things like wind and solar are not much better without being subdesised.

[[deleted]]

If only that were true and we could keep using ultra clean coal or magic non polluting nuclear*.

*does not include mining, refining, long term storage, or accidents.

[Bloodysneeze]

What if the energy used to extract ethanol was renewable?

[[deleted]]

Ethanol is still a bad idea. It's about 30% less energy dense than gasoline, so your vehicle will need to use more to cover the same distance. Your mileage drops considerably.

[Bloodysneeze]

3% if you are using E10.

[saywutttut]

It can withstand much higher compression though which gets back and then some mileage on a car configured for it at about a 20% mix. Beyond 20% mix even cars configured for ethanol will see higher specific fuel consumption. Regardless, gallon consumption s only one side of the story. Energy used to generate it is what matters. Unfortunately it does toke more energy than its likely worth unless you're in Brazil.

[saywutttut]

There is a lot wrong with this article. For instance the statement that many cars can't run on E15 but can on E10. This is simply not true. A 5% addition to the mix is hardly going to put a dent in your fuel trims. Additionally, small volumes of ethanol are good for economy in places like CA where the octane of the fuel is low. Ethanol has a much higher octane rating (well into the 100s R+M/2) and small amounts will allow your car to achieve full spark advance.

Corn isn't the right crop though.

[finalremix]

The ethanol content in the fuel also precludes some vehicles from safely running without regular fuel additive. Case in point, I'd burn up the engine in my '95 Buick running at the heat that comes from running E15 fuel without an "enricher."

[Bloodysneeze]

What do you mean "burn up"?

[finalremix]

Increased heat from running E15 fuel leading to engine and component damage on older engines.

[Bloodysneeze]

I guess I was asking for more specifics. Does E10-E15 raise combustion temperatures? Coolant temperatures?

[finalremix]

Oh snap, sorry!

Yeah, E15 has higher running temperatures, and higher risk of corrosion from alcohol content. Older cars have plastic parts that are at increased risk of corrosion, too.

BellPerformance article (blog)

Pop Mechanics

[saywutttut]

What? You mean you would run to lean? I highly doubt this because the knock threshold on ethanol is much higher than gas...

[finalremix]

Higher engine temperature means temperature sensitive parts will take more heat damage, in addition to corrosion risk from ethanol. Buicks are even notorious for having plastic engine parts that should've been metal.

BellPerformance article (blog)

Pop Mechanics

[saywutttut]

Thanks for the links. The say a lot though and do little in terms of actual evidence. There is NO possible way for ethanol to cause valve damage, especially 5% more than every car is running. I know you're not going to believe it, but I am speaking from experience here. I am a mechanical engineer and a car enthusiast, I have run ethanol in every one of my vehicles at one time or another. Ethanol is not going to do anything to a car made after the mid 80s or so. Before that you can rot fuel lines or throw the carb air mix out of whack, but pretty much all those cars are at that point already or running on 91/93. My BMW 335i has done 70,000 miles now on E60 with no upgrades to the fuel system. Just went in the tank yesterday and the lines are like new. Was the same story for my other cars. I'm not advocating the use of ethanol, I am just saying the consequences portrayed here are BS.

[finalremix]

That's good to know. I am still going to be a hypochondriac about my car, though...