please indulge me on a question re-ethanol

[mopinko]

i know that this has been discussed here, but i don't seem to be a very good searcher.
is it true that ethanol production consumes more energy than it provides? iirc correctly this assertion had some specious factors. i know there are a lot of other reasons why it is stupid. i would just like to know about this one line of "reasoning".
thanks.

[hobbit709]

1. From corn it does

In Brazil. they use sugar cane which gives a higher yield per acre. The other problem is that alcohol doesn't burn as hot as gasoline so you get lower mpg.

[Fledermaus]

13. Ethanol will give the same mpg as gasoline when used properly

Ethanol can use a much higher compression. Higher compression increases the engine efficiency and makes up for the lower energy content.

[GliderGuider]

14. Cool. Now answer his question, John...

[Fledermaus]

15. Whos question would you like me to answer, Paul???

I don't think Mr Hobbit had a question.

How are your stock picks doing today?

I don't know about you, but I sometimes have a social life on a Fridays & weekends other than DU.

[GliderGuider]

16. "is it true that ethanol production consumes more energy than it provides?"

That one.

[phantom power]

2. Grain-based ethanol appears to have an EROI of somewhere between 1 and 2.

In other words, you barely make an "energy profit." Given the environmental costs of growing that grain, it's not appealing.

Cellulose-based ethanol allows for better EROI, but my personal opinion is that the environmental cost is still prohibitive. It's also not clear yet how well cellulose-based ethanol can be commercialized, although at least one company has claimed to have industrialized it.

We could make a certain amount of either with acceptable environmental impact. I'm dubious that anybody will have the self-control to stop at that limit.

[GliderGuider]

3. There's lots of debate on that point

A lot depends on how creative or stringent your energy accounting is, and where you set the process boundaries for accounting purposes. I've seen EROEI numbers for corn ethanol from about 0.95:1 up to 1.4:1 or so. A common number is 1.3:1.

Ultimately this debate is like arguing about how many angels can dance on the head of a pin. Even an EROEI of 1.5:1 isn't good enough to offset the externalized costs of corn production - the soil and water depletion, the eutrophication from fertilizer runoff etc.

Some analyses I've seen conclude that an overall energy return less than 5:1 isn't enough to power an industrial civilization like ours. That If that assessment is correct, it implies that agrifuels may have some niche applications, but trying to give them a major role will ultimately be self-defeating. Not that this will keep us from trying, of course.

[patch1234]

4. no. gain is usually stated as 30% or so.

the real benefit is avoided use of petroleum.

[OKIsItJustMe]

5. As the others suggest, it's not a simple question/answer...

... since there is more than one way to produce ethanol.
http://www.democraticunderground.com/discuss/duboard.php?az=show_mesg&forum=115&topic_id=130999&mesg_id=130999

However, in the US, using corn ethanol, estimates vary from it being a net loss of energy to it being a very narrow gain. On top of it all, you're essentially running your car on food.


However, what if grew corn (as we do now) and then used the non-food portions of the plant to make ethanol? (Essentially producing a new product from a waste product?)

Here's a reasonably balanced look at things:
http://web.mit.edu/newsoffice/2007/ethanol.html


So, ethanol might not be all bad, but the ethanol you find at your local station in the US pretty much is...

[GliderGuider]

6. Using non-food portions of plants to make ethanol

Are you factoring in the long-term loss of soil nutrients and soil quality that results from this practice? If we do this, then we are not just removing the food portion of the plant from the field, but the whole thing. All of the plant's biological contribution is removed, and must somehow be replaced. Carrying away all the organic material from a field amounts to strip-mining the soil, and I have some serious concerns about the long-term (hell, even the short-term) implications of that. Remember that even corn stover is only "waste" from the human perspective. Other denizens of the biosphere look on it as an essential raw material.

[patch1234]

7. starch has no nutrients

typically, only the starch is used to produce
ethanol, the protien is used as animal feed.
soil nutrient issues , IMO, no different
than other feedlot operations.

[GliderGuider]

8. And you don't see a problem with "feedlot operations"?

It's just as management problem to you, isn't it? Why should we give a fuck about the other life on this planet, or even our own grandchildren? Let them fend for themselves, right?

You don't have an ecological bone in your alleged body, do you, you wretched sockpuppet?

[OKIsItJustMe]

10. Little short on sleep GG?

(You're not usually one to resort to name calling.)

[GliderGuider]

11. I had that sockpuppet on ignore.

I turned off the flag. That was a mistake. It pisses me off.

Even my usual Olympian detachment has its limits, I guess.

[ConcernedCanuk]

17. Interesting phrase "sock puppet" - yup it's actually two words

.
.
.

According to Dictionary.com

sock puppet

n. (Usenet: from the act of placing a sock over your hand and talking to it and pretending it's talking back)

In Usenet parlance, a pseudo through which the puppeteer posts follow-ups to their own original message to give the appearance that a number of people support the views held in the original message.

To get back on topic -

Does anyone know what the energy used is in comparison to oil?

Without that figure, the numbers presented here don't hold much relevance for me.

And I already know about some of the disastrous effects on the environment our quest for oil has created, and it's gonna get worse as we "scrape the bottom of the barrel" so to speak with our injections of gas, steam, water or whatever to drive that precious stuff up where we can grab it

And our own Alberta tar sands may be one of the worst environmental scars in our country that we will regret long after the deed is done

[NickB79]

12. Numerous soil microbes digest starch

That's how we make ethanol from starch: we use bacteria to digest the starches, producing ethanol as a byproduct.

That same process fuels the microbes that make up the base of the soil ecosystem that keeps fields fertile. Remove the starches of plant stalks and leaves, and you destroy the soil ecosystem.

[OKIsItJustMe]

9. Well, you may want to check out the link I provided

You may also want to check out some of the papers here:
http://lfee.mit.edu/metadot/index.pl?id=2234


However, I generally agree with what you're saying. Soil management is an important thing, and something which our modern farming industry could be much better at.

In another post, I mentioned (for example) that "switchgrass" might make a good crop to grow in rotation with legumes (e.g. peanuts.)

[Fledermaus]

18. No, it doesn't consume more energy than it provides.

At one time, at the turn of the century, you could go for a drive in the country and purchase your fuel from a farmer...ethanol

Unlike gasoline production, witch does consume more energy than it produces, ethanol has a true positive energy balance.
More importantly, biofuels can be carbon negative.

Tilman's prairie grasses bury much of that CO2 in the soil and in their deep, permanent roots. So a good deal of the CO2 stays in the ground after the harvest.

"We have discovered a way to make biofuels that by the time the whole life cycle is done and they are combusted, there is less carbon dioxide in the atmosphere than there had been before," Tilman says.
http://www.npr.org/templates/story/story.php?storyId=6594253