[Stoves] Heat destroys Jatropha toxins Re: jatropha, stoves, and biochar.

[Kristen Matsumura]

My background research of jatropha toxins has revealed that most of
the toxins break down with heat, however the behavior of phorbol
esters are less certain. Phorbol esters break down at high
temperature, which has been shown to be effective in the combustion in
diesel engines. However no research has been done to show how they
breakdown when used as fuel for a cookstove.

Attached are two articles that talk about the behavior of phorbol
esters in jatropha.

Kristen Matsumura
Civil Engineering Graduate Student
University of Colorado at Boulder




On Wed, Jan 26, 2011 at 10:31 PM, Crispin Pemberton-Pigott
<crispinpigott at gmail.com> wrote:
> Dear Jatropha Planters and Burners
>
>
>
> This is a response from David House, he of biogas fame. Fortunately we
> overlap on a different environmental list.
>
>
>
> From: David [mailto:david at h4c.org]
>
> On 1/26/2011 6:39 PM, Crispin Pemberton-Pigott wrote:
>
> Dear David
>
> There is a big discussion going on at the stoves list (bioenergylists.org)
> about burning jatropha seeds or seed cake.
> If it is burned, is there any risk of creating dangerous fumes?
> If it is pressed first then burned?
> If it digested, then burned?
>
> Honestly I don't know of any references to determine whether any of the
> options listed might be harmful. I do know that burning the glycerol which
> results from transesterification can produce poisonous fumes (acrolein), but
> never investigated burning the seed cake-- I was hired for example by one
> client to find out if it would digest, and it does, easily. (I am attaching
> the report herewith.) (At the same time, it would not make sense to burn it
> after digestion-- it would be too wet.)
>
> As well, with regard to composting the seed cake and using that as
> fertilizer, I would feel quite satisfied-- even though in this case as well,
> I cannot provide a peer-reviewed source-- in saying that it will not harm
> the soil.
>
> After all, whatever is composed, decomposes. What poisons the soil is either
> elemental-- too much copper, for example, can harm plants-- or it is
> biologically recalcitrant. Now, what is recalcitrant often depends on what
> is in the soil. Some substances (particularly man-made ones), nearly
> regardless of where they end up under the surface from the arctic to the
> equator, are recalcitrant; but with others, a great deal depends on what is
> available in the soil that can make some sort of feast of it. If the soil is
> dead, then it is much easier for something toxic yet decomposable to
> accumulate, and after all, something was probably put on the soil to kill
> it-- likely chemical ag of some sort. Build up of some toxic-yet-degradable
> substance would simply be another side effect of the main problem.
>
> Ecologically speaking, some plants build toxicity to their own seedlings in
> the soil below them. Peach trees, if memory serves, have this effect, and as
> such peach trees will never form a climax forest. But that is not toxicity
> in any general sense. I have read a lot of reports about Jatropha, and there
> is enormous literature about co-plantings of this and that with Jatropha,
> because the bush/tree takes 5-8 years to get established, so people have
> done all sorts of things to make the land productive by planting between the
> rows, both early on, and later even in mature stands. In all the reports I
> have seen about co-plantings, I have never seen any mention of toxicity.
> Now, this is a sort of negative evidence, in two senses. First, I am not an
> expert, just an interested amateur. No doubt there is a vast literature
> which I have never seen. And second, obviously, absence of evidence is not
> evidence of absence. Even so, I would think that if Jatropha in fact poisons
> the soil, then it would be relatively common knowledge, and at least a few
> of those articles would have said "Don't plant X with Jatropha. It dies."
>
> To return to the question of toxicity when burning, I would think that an
> enormously complex set of chemicals would be released from any combustion,
> unless done under conditions that would guarantee that all parts of every
> particle of the seed cake were exposed to the same conditions of heat and
> sufficient oxygen. They won't be. So my assumption would be that whatever is
> toxic in Jatropha when eaten would be present in the smoke, along with a
> whole alphabet soup of other substances. WHO says 1.6 million die each year
> from smoke inhalation and related causes, and surely most of what's burned
> is harmless cellulose and lignin and all those other innocents. I can't see
> that adding poison oak to the fire is likely to result in smoke that is less
> dangerous-- there is literature available about that bad idea-- and the same
> would sensibly be true of Jatropha seed cake. It's got bad stuff for mammals
> in it if they eat it, so surely some of that would show up in the smoke and
> would offer its measure of harm when the smoke inhaled.
>
> But again, for the most part that's just me gibbering, and not reel scienze.
> --
>
> David William House
>
> "The Complete Biogas Handbook" www.completebiogas.com
> Vahid Biogas, an alternative energy consultancy www.vahidbiogas.com
>
> "Make no search for water. But find thirst,
> And water from the very ground will burst."
>
> (Rumi, a Persian mystic poet, quoted in Delight of Hearts, p. 77)
>
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