<Why We Drive The Oil Drum DrumBeat: December 14, 2006>

27 comments on An Update on US Gasoline Stocks and Blending Components

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nelsone on December 14, 2006 - 12:44am Permalink | Subthread | Comments top
It gives you an idea just how stable the 95:5 EtOH:H2O azeotrope is, that ethanol can overcome the enormous entropy of mixing, and just come crashing out of E10 with the slightest addition of water. Drying ethanol is quite the pain, too: In lab applications it's fractionated with benzene, so there's always a few ppb of the nasty C6H6 left in it. I have no idea how it's dried on an industrial scale.
But the idea of using partially burned fuel never made much sense to me, and even the most cursory back-of-the-envelope shows that there's insufficient arable land to replace any significant fraction of our FF use with EtOH anyway. Unless we choose to starve off a lot of people, that is.
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Jack on December 14, 2006 - 1:39am Permalink | Subthread | Parent | Comments top
even the most cursory back-of-the-envelope shows that there's insufficient arable land to replace any significant fraction of our FF use with EtOH anyway.

That depends on who we are and isn't really a very useful metric anyway. Brazil has replaced over 10% of all liquid fuels  and over 25% of all gasoline use with ethanol(both measures on a on a BTU basis).

Thailand, where I live, is about to do the same thing. This to my mind will replace a significant fraction of our oil consumption.

Ethanol from sugar cane has a respectable EROEI and reduces greenhouse gasses from vehicle use by over 80%.

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InfinitePossibilities on December 14, 2006 - 4:33pm Permalink | Subthread | Parent | Comments top
And how much of their net oxygen producing rain forest had to be burned to have area for the sugar cane? How long will it take until those areas drop in productivity because the minerals are being washed out of the ground?

The only known methods to produce energy from solar radiation with a good EROEI are solar cells and thermal solar plants. Everything else is a waste of time, land and taxpayer dollars.

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Oilrig medic on December 14, 2006 - 4:44pm Permalink | Subthread | Parent | Comments top
Don't you think there are infinite other possibilities? How about managed forestry for firewood?  If the EROEI of firewood was bad the woodstove would be a foolish invention no?
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Jack on December 15, 2006 - 7:11am Permalink | Subthread | Parent | Comments top
And how much of their net oxygen producing rain forest had to be burned to have area for the sugar cane? How long will it take until those areas drop in productivity because the minerals are being washed out of the ground?

The rainforest was burned primary to feed cattle for meat. There is very little linkage between sugar production and rainforest destruction. Brazil has produced sugar and ethanol for thrity years and yields have improved vastly. They are now working on organic production.

The only known methods to produce energy from solar radiation with a good EROEI are solar cells and thermal solar plants. Everything else is a waste of time, land and taxpayer dollars.

That is just a falsehood. Sugar cane to ethanol has an EROEI of 8-10. I advocate solar, but at the moment ethanol makes more sense from economic and energy perspectives. Engineer Poet wrote a whole poast recently about other ways to transform biomass to energy. Read it.

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Starship Trooper on December 14, 2006 - 1:36pm Permalink | Subthread | Parent | Comments top
The ethanol azeotrope is dried using molecular seive technology at the industrial scale.  It aviods the trinary distillation issue.  However, in gasoline applications, the small amount of benzene that would be carried out through the distialltion would not be an issue since gasoline contains a percentage or two of benzene.  

A reasonable back of the envelope calculation would tell you that for reasonable outputs of cellulosic-based ethanol, the amount of land required to completely replace gasoline usage (on an energy basis) is about twice the land area of all of the US (including Alaska).  Since corn is a bit particular about where and how it grows, I can't imagine it growing on the slopes of Denali, Hunter, or Foraker anytime real soon.

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27 comments on An Update on US Gasoline Stocks and Blending Components

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