[Digestion] Cattails

[Duncan Martin]

Holy Moses!

Thanks to Wikipaedia, I now know that cattails are what the British call 
bulrushes -- probably not the same species as the infant Moses was 
discovered afloat in - but probably the nearest equivalent available to the 
translators of the Bible.

(I can see where the name "cat tail" comes from too -- very graphic! Why 
"bull" rush, I wonder? Perhaps from a comparison with the common rush, which 
lacks the massive, phallic, flower/seed head of the bulrush?)

Now, the bulrush MIGHT be a very productive plant AND an ideal substrate for 
conversion to ethanol. The former would be likely in a semi-aquatic 
ecosystem but I have to say I find the latter unlikely, since it is not a 
plant I associate with high concentrations of starch or sugar. (The original 
research mentioned was only vaguely referenced, so I have been unable to 
find it.)

However, let us consider the practicalities. Bulrushes only grow in marshy 
areas and at the edges of rivers and lakes.  Although there are areas in 
which such land is quite extensive, there are no vast expanses of marsh that 
we could turn over to biomass production.  Even if there were, it would be 
difficult to adapt them to modern, mechanised, farming techniques.  I 
suppose we could conceive of a world so desperate for energy that much of 
the temperature zone would be converted into a vast artificial bog farmed by 
an army of peasants -- but I do not think we have reached that stage yet.

I cannot think of any other way in which bulrushes could make a significant 
contribution, even if the plant itself is ideal.  Am I being too sceptical?

I do concede that we must be open to all new ideas -- and to many old ones 
that have been dismissed in the past, perhaps wrongly, perhaps because the 
circumstances were different then.

Duncan J Martin

Centre Councillor
Republic of Ireland Centre
Chartered Institution of Wastes Management

================================
CONTACT DETAILS
Duncan J Martin, PhD, CEng, CSci, MIEI, MCIWM, MIChemE
24 Townsfield, Cloughjordan, N Tipperary, Ireland
Mobile: +353 86 8377 906
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Email: duncanjmartin at eircom.net
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----- Original Message ----- 
From: "Duncan Martin" <duncanjmartin at eircom.net>
To: <digestion at listserv.repp.org>
Sent: Wednesday, December 19, 2007 5:48 PM
Subject: Re: [Digestion] cellulosic ethanol process


> Dear all that
>
> Bear in mind that finding a 'magic' organism capable of direct conversion 
> of
> cellulose to ethanol is only 1% of the battle, so let's not get too 
> excited!
>
> Researchers' press releases tended to be based on: (a) a compelling need 
> to
> announce the most trivial advance as a breakthrough and (b) a pretty
> comprehensive ignorance of the realities and economics of process
> engineering.
>
> Cellulose is a "difficult" substrate, resistant to microbial breakdown,
> partly because it is highly insoluble. That is why plants evolved it.
>
> The degradation of cellulose in nature is commonly effected by complex
> consortia of microorganisms -- which often need to include the relatively
> few fungi that can degrade the lignin which cellulose is often wrapped up
> in. Consequently, the decay of cellulosic materials is typically slow --  
> it
> can take years in the case of woody (lignin-rich) materials.
>
> It is therefore likely that the rate of conversion from our magic organism
> will be too low to be of any commercial use.
>
> Another problem is tolerance to product inhibition.  Ethanol is toxic, to
> microorganisms, as it is to us. The yeasts we use in conventional
> fermentation have an unusual natural ability to tolerate high levels of
> ethanol, enhanced by selective breeding in the capable hands of 
> generations
> of brewers, winemakers and distillers.
>
> Consequently, our magic organism might only be capable of generating a 
> very
> dilute solution of alcohol, so that the energy required to distill it to 
> any
> useful concentration as a fuel would be greater. (There was similar
> excitement among researchers some 30 years ago over the prospect of using
> the bacterium Zymonas mobilis to produce ethanol from soluble substrates.
> However, it could not produce high concentrations and, as far as I am 
> aware,
> has never been used in a commercial process.)
>
> While I am writing, could I ask contributors to avoid the use of local 
> names
> for plants etc? (When I read about digesting cat tails, I am tempted to
> suggest digesting the whole cat!) I presume the cattail is a plant.  Is it 
> a
> weed, as its colourful name suggests?  Or a crop? What is it used for?
>
> Duncan J Martin
>
> Centre Councillor
> Republic of Ireland Centre
> Chartered Institution of Wastes Management
>
>
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