Ethanol from Biodiesel Byproduct

Biotech reports that scientists have found a way to convert glycerin, a byproduct of biodiesel production into ethanol.

Ramon Gonzalez and Syed Shams Yazdani have identified the metabolic processes and conditions that allow a known strain of Escherichia coli to convert glycerin into ethanol through an anaerobic fermentation process.

Gonzalez found that ethanol from glycerol is 39 cents cheaper to produce than ethanol from corn. Feedstock costs per gallon were 53 cents for corn, versus 30 cents for glycerol. Per gallon operating costs were 52 cents for corn and just 36 cents for glycerol. . . . more

I would think this technology would only be applicable to larger biodiesel plants, of which there are not too many in the U.S., but probably more in Germany.

Comments

[Engineer-Poet]

Feedstock is one thing, but what about distillation?

The distillation step is very energy-intensive, and it depends greatly on the concentration of ethanol in the fermentation products.  Yeasts can have very high ethanol tolerance, which reduces the energy in the distillation step.  How much ethanol can these E. Coli tolerate before their conversion stops?  If it's not high enough, even free feedstock won't compensate for the extra fuel required for the still.

[Gary Masemeng]

I totally agree with the 'Engineer-Poet' about the energy intensiveness of distilling the residue of Biodiesel extraction, yet if you combine the energy output from both end-products (biodiesel & ethanol) against the energy consumed in their extraction; it would still be commercially viable and feasible exclusively to larger biodiesel plants who naturally deal with larger cubic volumes of the input biomass.

All I am saying is that proportionally the energy consumed ratio against the energy output ratio would be very positive, especially considering that only one feed stock has been used to produce two tiers of greener fuels.

But yes, this would only be viable to massive biodiesel plants which source their biomass feedstock in bulk at very cheap rates.

Good discussion

Regards

Biomass Insurer

[Engineer-Poet]

if you combine the energy output from both end-products (biodiesel & ethanol) against the energy consumed in their extraction; it would still be commercially viable and feasible

You appear to be saying that the production of ethanol by the fermentation of glycerine is commercially viable regardless of the return on that step, even if this makes the operation less profitable than just disposing of it.

I think this is hooey, but I can't see any other way to interpret what you said.

All I am saying is that proportionally the energy consumed ratio against the energy output ratio would be very positive

What guarantees that?  How much energy, and in what form, is required for distillation?  How much cost to amortize the fermentation vessels and still?

especially considering that only one feed stock has been used to produce two tiers of greener fuels.

Non sequitur.  You could feed the carbon dioxide to algae to produce more fats and carbohydrates, but that doesn't automatically make it profitable.

But yes, this would only be viable to massive biodiesel plants which source their biomass feedstock in bulk at very cheap rates.

Why does scale matter?  You assert this without any obvious factual backing.

Decomposition of glycerol (heat of combustion 4270 cal/g or about 16.4 MJ/mol) to 3 moles of carbon monoxide (283 kJ/mol) and 4 moles of hydrogen (241.9 kJ/mol) is slightly endothermic, so a bit of oxygen would probably suffice to gasify it.  This would yield a syngas which could be cleaned and converted to just about anything, from alcohols to F-T diesel.  Or at a small scale, it could be gasified and used for process heat or cogeneration fuel.  Making ethanol for ethanol's sake might lose energy, and make money only because of subsidies.

[nucbiodieseltieburner]

Gentlemen,
I think you need to check your Glover Handbook or the CRC Manual and see what the specific gravity of glycerol is compared to ethanol. Then you would see that gravity it the primary separation system.

[Engineer-Poet]

Ethanol is infinitely miscible with water, and E. Coli needs at least some water to live in.

[Saul Wall]

Was there not just a recent story in the news about using filters as a low energy alternative to distillation?

[Engineer-Poet]

The filters I've seen news about are permeable to water, and are used in the final purification of 95% ethanol to anhydrous ethanol (required for blending with gasoline, because water causes separation). These filters are less energy-intensive than using zeolites for dehydration, but wouldn't improve the penalty imposed by going from a 12% ethanol mixture to a 5% ethanol mixture.

(What, is TEB not accepting Wordpress URLs any more? Mine is being rejected as "invalid".  And so's Blogspot.  WTF?)

[Aleks]

Anyway, it production costs is out of discussion, if it is 0+. Ethanol producing from biodiesel byproducts decrease using food as a fuel.