Butanol seems to have great advantages over ethanol, but all the information looks like it's single source and just regurgitated on many websites. I'm looking for a chemist or someone with technical expertise, to tell me why it has not jumped to the forefront and become the alcohol of choice. I receive several biofuels newsletters and ethanol plants are popping up all over, and the limited information I see tells me they should be Butanol plants. There is a technique to produce Butanol that is more efficient than the ABE process.
So are you or do you know someone with the expertise to explain this
seemingly poor biofuels choice.
Here's a DOE paper (read the abstract)
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I don't want to hear the food or fuel argument, this could be made from cellulosic or algae feedstocks.
When I was looking up on Ethonal I ran across it and I thought the same. But IIRC there was one sticking point for it that make it less viable than Ethanol.
Potential problems with the use of butanol fuel The potential problems with the use of butanol are similar to those of ethanol:[citation needed]
a.. To match the combustion characteristics of gasoline, the utilization of butanol fuel as a substitute for gasoline requires fuel-flow increases (though butanol has only slightly less energy than gasoline, so the fuel-flow increase required is only minimal, maybe 10%, compared to 40% for ethanol.) b.. Alcohol-based fuels are not compatible with some fuel system components. c.. Alcohol fuels may cause erroneous gas gauge readings in vehicles with capacitance fuel level gauging. d.. While ethanol and methanol have lower energy densities than butanol, their higher octane number allows for greater compression ratio and efficiency. Higher combustion engine efficiency allows for lesser greenhouse gas emissions per unit motive energy extracted. As an advantage, butanol production from biomass could be more efficient (i.e. unit engine motive power delivered per unit solar energy consumed) than ethanol or methanol routes. Also, some bacteria that produce butanol are able to digest cellulose, not just starch and sugars.[citation needed]
But the main issue is
Research challenges The key research challenge that must be resolved is that butanol production inhibits microbial growth even at low concentrations. The result is that the product of the fermentation is less than 2% butanol. The overwhelming majority of the fermentation broth is water, so an energy-intensive distillation step is required for purification. This may be acceptable if the goal is to produce butanol for use as a solvent, but if butanol is to gain traction as a motor fuel, energy inputs into the process need to be minimized.[15]
The Swiss company Butalco GmbH uses a special technology to modify yeasts in order to produce butanol instead of ethanol. Yeasts as production organisms for butanol have decisive advantages compared to bacteria.
I personally couldn't tell you but before long DuPont and BP will be able to, as they are building the first butanol as motor fuel plant in the UK. It should be online soon.
DuPont claims to have some enhanced process AIUI that overcomes some traditional difficulties brewing the stuff (and DuPont has a good record). Good luck to them since this isn't AFAIK some mega subsidised gov't programme.
Ethanol is frequently distilled using something like an osmotic membrane:
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I believe its much more efficient than the vaporization process. There was some news about a small home ethanol plant that fermented sugar and distilled the product for motor fuel use. It used the membrane method.
That's interesting. A similar process for the wine industry has become controversial in Europe. Using membrane filtration to extract water from low-grade grape juice or wine concentrates the flavor, but some wine fans seem to think this is cheating or somehow violates the wine-making tradition.
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