[Stoves] Jatropha and its future

Jan Bianchi janbianchi at comcast.net
Wed Aug 17 11:19:54 CDT 2011


Dear Boston

 

Thanks for your cite.  Professor Makkar's studies have focused on how to
detoxify jatropha seeds to make them edible for animals.  One of the
projects that he and his colleagues are working on is the use of jatropha
oil in cookstoves.
http://ec.europa.eu/research/agriculture/pdf/events/4jatropha_en.pdf   I
don't think it would be accurate to imply that he opposes these efforts.  

 

As an amateur woodworker, I am also well aware that wood is full of toxins.
See this list for a start.
http://www.dave-wilcox.com/Woodturning/toxics.aspx.  I choose to build
furniture nevertheless.

 

Interestingly, both the curcin and the phorbol esters in jatropha seeds can
have a tumor-inhibiting impact too. 

 

http://www.academicjournals.org/ajpp/pdf/%20pdf2009/November/Balaji%20et%20a
l.pdf

Phorbol

esters are co-carcinogens which themselves do not induce

tumors but promote tumor growth following exposure to a

subcarcinogenic dose of carcinogen [13]. Apart from the

co-carcinogenic activity, many phorbol esters (reported

from other plant source) also exert beneficial biological

effects without tumor promotion, such as prostratin [75].

Some naturally occurring phorbol esters are reported to be

tumor inhibitors [76] and Phorbol 12-tigliate 13-decanoate

has been shown to be active against the P 388 lymphocytic

leukemia in mice [77, 78].
https://jatropha.uni-hohenheim.de/uploads/media/7--diterpene_review_02.pdf

 

 

Just a reminder about how complicated this all is.  As with many things, it
is a matter of degree.  None of these articles address either degree or how
these properties may behave in smoke.  Therefore, the need to study this
further.  You are absolutely correct that the testing needs to include smoke
at all stages of the burn.

 

Jan

 

  _____  

From: stoves-bounces at lists.bioenergylists.org
[mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Boston Nyer
Sent: Tuesday, August 16, 2011 10:53 PM
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Jatropha and its future

 

FYI: In addition to being toxic when ingested (as previously discussed),
some phorbol esters can activate tumors.  Although compounds may break down
during the normal cycle of the stove, they may not when it is being lit.
When testing the toxicity of emissions from J stoves, we must test at the
various times during pyrolysis.  In my opinion we should be extremely
cautious regarding the toxicity before promoting this stuff.  If you are
interested in literature on the toxicity of Jatropha, Harrinder Makkar at
the University of Hoffenheim has published a significant amount.

Boston



On Tue, Aug 16, 2011 at 10:11 PM, Crispin Pemberton-Pigott
<crispinpigott at gmail.com> wrote:

Dear Roger

 

>I am curious if this "log" was an extruded or pressed product. 

It is a pressed/extruded log (same thing) using no binder save the lignin in
the material. The diameter is about 110 mm and the length about 250/300mm -
will check.

The colour is 'pine' so I would say, golden.

>.The moisture content is known to be about 8%. 

It varies with storage. The production process dries the wood almost
completely (hot) and it picks up some moisture after that.

>It is approx 8500 btu/lb, 

That would be 8500 x 1055 x 2.2046 (lbs/kg) = 19.8 MJ per kg which is
definitely a 'dried' energy content.

With 8% moisture it is about 17 MJ/kg for typical hardwood.

>.and gives a burn time of up to 12 hours (in our stove) 

It is important that you express this burn time together with a kW rating
(or BTU if you can work that out instead).

A couple of contributors explained this before but here is a repeat:

8500 BTU's / lb in the 2.2 kg log.

That is 8500 x 1055 x 2.2 = 43,493,000 Joules total heat content (43.4 MJ)

One Watt is 1 joule per second of energy.

12 hours = 12 x 60 minutes x 60 seconds = 43,200 seconds.

43,493,000 Joules / 43,200 seconds = 1007 Watts average heat output on a
continuous basis. That is the same as saying 'the power output is 1 kW'
average.

>Funny thing is I get more smoke at a higher heat output than the medium to
lower end. 

That has to do with the availability of secondary air and the combustion
environment (including its physical size).

>Estimated [heat] output at 27,000 high, 5,000 btu low output. 

Per what? Per hour? Per day? It is not clear. 5000 BTU's is 5.275 MJ. If
that was per hour, it is 1.465 kW. The 27,000 = 7.9 kW. If it takes 12 hours
to burn the log, (and in fact there is still some coals left) it averages 1
kW heat output average.

An earlier point I was making about Mongolian space heating is that the
homes need between 4 and 12 kW on a continuous basis. We would need to burn
at about your 'medium' power level continuously to keep the place warm. The
largest stoves we work with in homes are 20 kW, equivalent to about 1.3 kg
of wood per hour (depending on the moisture content).

Any stove sold there has to be able to cook a 16 inch diameter wok, and to
boil 9 litres of water (in the wok) in less than 1.5 hours from ignition (or
it won't be considered at all for the programme). Some stoves can boil it in
30 minutes, but 90 is the upper limit. Mass production facilities are
available. It has to retail under $150.

Good luck with the EPA testing and alla that. Please keep us informed about
how it goes.

Crispin


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