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30 comments on Questions and Answers on Energy Issues

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memmel on October 21, 2007 - 12:00pm Permalink | Subthread | Comments top

I really like butanol also. What about higher alcohols. The beauty of butanol and higher alcohols is if you can get the fermentation to work to the solubility limit then you have basically water free alcohol that can be simple poured off.

The key for alcohol fuels when you look at EROI really seems to be to eliminate the distillation step.

Maybe someone could do a overview on the various fermentation technologies and their relevance to fuel and if they can be done without a distillation step.

And what about other fermentation products alcohols are not the only choice ketones could be interesting. Carboxylic acids can be isolated as a salt and thermally Decarboxylation

http://www.chem.ucalgary.ca/courses/351/Carey5th/Ch19/ch19-3-4.html

If you consider the wealth of possible fermentation products and our ability to do dna modification it seems reasonable to assume that a good approach could be found.

http://www.fao.org/docrep/x0560e/x0560e00.HTM

Although I agree that corn/ethanol and probably ethanol in general is probably not the right solution the sheer number of possibilities makes me believe that in time a good solution can be found.

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robert2734 on October 21, 2007 - 12:39pm Permalink | Subthread | Parent | Comments top

The ugly about butanol and larger chain alcohols is that they are so toxic, it is hard to design bugs that can survive up to the solubility limit.

What about seperating water and alcohol with filters the way they desalinize water?

RobertInTucson

I haven't escaped from reality. I have a daypass.

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Gilgamesh on October 21, 2007 - 6:32pm Permalink | Subthread | Parent | Comments top

Alright.

Desalination of water via hollow wound fiber membranes, reverse osmosis.

You need shittonnes of pressure. I am also unware of the solvent activity of butanol in water. This is a considerable problem, if the solvent activity is too low, nothing will flow. This would actually be a difficult problem to solve, because it is typically designing the polymer membranes which is difficult. You would need to select for a polymer membrane which was specific for butanol and not ionic molecules. (or specific for water and not butanol, then you collect the rejection). Efficiency will be high, but prefiltration will be needed, 1 for dirt, 1 for bugs, 1 for smaller particles.

Even larger problems will occur if butanol does not dissolve in solution, the micelles will not want to go through any of the above filters, so you would have to mess with the water chemistry at that stage.

You would probably be better off using gaseous stripping, collect water at some location, bubble significant volumes of air through it, cool that air, reheat the exit water with the exchange heat, collect the resulting butanol.

toxicity is not a problem so long as you can keep the concentration low. However the pressures on each side of gas / liquid interface are proportional, I have seen studies about alcohol distillation noting some 30% of the produced ethanol in batch was lost by gaseous stripping. The extracted ethanol was then refluxed into the original mix.

G

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Cld12pk2go on October 22, 2007 - 11:45pm Permalink | Subthread | Parent | Comments top

I love the unit of measure "shittonnes". Nice.

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practical on October 21, 2007 - 1:08pm Permalink | Subthread | Parent | Comments top

RR, I've finally found something I can wholeheartedly agree with you on, namely posting and lurking. JHK showed me the way. Every week he puts out on Monday and every week Dangerbird or someones else poops on his effort. The next week JHK ignores it all and posts another one on Monday morning presumably because he enjoys writing. Responding to critics is a waste of time, just assume your ideas will be torn to pieces and post them anyway. It's the nature of the Internet with it's anonymity and ease of response that makes taking critics seriously a bad idea. And it's more fun ignoring critics. Successful politicians and public figures all have to learn to ignore critics. Usually I don't respond to anyone anymore if it's about something I posted. I don't even read the critics. All it does is lead to a shouting match. No one's mind will be changed. The critics can put one is such a bad mood that giving up posting seems like a good option. I will sometimes respond to what others post. And others can take it or leave it, I don't care. The benefit of this is that the lurker, which is what I usually am, gets more enlightenment, enjoyment and fewer heated arguments.

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Gilgamesh on October 21, 2007 - 6:57pm Permalink | Subthread | Parent | Comments top

all alcohols will be soluble in water (that pesky hydroxyl group), large enough alcohols to precipitate out of solution will not be made by small organisms (the single chain high MW ones we want).

You can attempt to complex them, but the complexes must be recoverable and economical to produce (this is shifting the buck). Anything which complexes a simple CCCOH will also probably complex with H2O or be serverely messed up by its presence. Any other alcohols present will also complex.

dna modification is in its infancy. We actually do nothing truely difficult. We observe in nature and then cut and paste.

See a gene you like? chop it out, splice it into a bacteria, and see what happens.

There are no human designed proteins or reaction chains currently which produce anything. Monsanto probably has the most advanced private labs in the world with regards to this. The best they have come up with is a crop which is sterile the next season.

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memmel on October 21, 2007 - 11:26pm Permalink | Subthread | Parent | Comments top

I'm not suggesting that we can solve this problem in a reasonable way in the short term but these types of problems are ones that will fall to a 20-30 year effort.

And I think the goals will be different since over this time period we will convert to electric completely outside of the airline industry. And even here we may see a move to fuel cells for a lot of flights.

It's important to understand I don't give a rip about people thinking of creating liquid fuels to keep the current economy going this a waste of time.

But even in the brave new world of the post oil economy we need liquid organic fuels and probably more important feed stocks for chemical synthesis. And I'm sure that the people of this period would treat using fossil fuels with the same horror we do for nuclear now.

Now for these uses cases you don't want to waste good farmland or the edible part of the crop so your looking at cellulose IMHO.

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30 comments on Questions and Answers on Energy Issues

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