[Stoves] central secondary air

Crispin Pemberton-Pigott crispinpigott at outlook.com
Wed Dec 17 11:19:07 CST 2014


Dear Paul


1.  I do not have a high regard for the Mayon rice husk stove.   My
experience was limited and several years ago, but I have not read of any
substantial changes to the stove since then.   

 

I was asked to have a go at it with two interns and that took place in my
Waterloo workshop. The final results was a doubling of the system efficiency
(maybe more) and the principal change was to reduce the amount of secondary
air. At the time I was not in the least interested in producing rice hull
char and tuned the burn to consume as much of it as possible. Because the
stove is fed episodically and produces char that is easily removed while it
is running, you could simply decrease the effectiveness of the combustion
and have a higher carbon content in the char/ash. It would of course use
more fuel to cook.

 

And we do not hear that it is being well accepted somewhere.  

 

I think Roger is pretty fed up with the treatment he got from the Stoves
group - particularly the mis-reporting of the (very low) emissions in a
publicised report that led to the threat of law suit. Why should he share
anything? What did we do for him? He developed the entire concept out of
thin air. It does all sorts of things people are still striving for.  It is
not perfect, but it works and uses waste biomass and can be made and
repaired locally. I only know of two countries where they are produced,
maybe three because Eastern Gambia might be involved as well.

 

2.  Where do I go to read the results of what stoves have passed the
requirements of the Indonesia project?   Did I miss an announcement?   IMO,
things like that should be announced with glee and fan-fare!



Well, not surprisingly it was in Indonesia! I think you can find the links
at the Collaboration for development 'C4D' site. No time to look it up now.
It will include the word 'launch'. (Wasn't it posted here?) The next step is
proposals from market aggregators who will develop making and value chains
(on their own) and hopefully sell stoves people want to buy.  The approved
stoves are not the 'usual suspects'. There are many new entrants. "Approved"
means the product scored at least 1 star in each category of CO, PM and fuel
efficiency. There are more stars available which attracts a higher subsidy
to the vendor.


3.  I am glad to hear that some TLUDs are approved in Indonesia, EVEN THOUGH
THERE IS NO RECOGNITION FOR THE CHARCOAL PRODUCED (unless it is somehow
consumed later in the same stove).   

 

I think you have to consider what 'recognition' means in the context of an
improved stove programme (only). There was no component in the pilot to
create charcoal. We are creating a distribution system into which any stove
can be inserted (if there is demand).  The private sector now takes over and
promotes stoves. If one of the promoters wants to, they can advertise the
heck out of the char making 'function' and see who is interested. We are not
ramming products down people's throats. We are also not picking 'winners'.
Anything that comes by is rated. There is a minimum to get homologated.

 

It will be very interesting to have some study done (even if rather informal
observations) about what the users of those stove actually will do with the
charcoal, and if the char is acknowledged by the users as having some value
or importance.   

 

That would show up in the public response.

 

I agree with Crispin that char is no longer the same as the original biomass
fuel.  Kg of biomass into the stove is gone (when calculating FUEL
efficiency) even if there is about 20% of the Kg weight coming out as char
(which is about 30% of the energy value of the biomass and about 50% of the
carbon atoms of the biomass.).   

 

The metric involved  was fuel efficiency. We have been over this many times
on the list mostly for Ron's interest and the difference should be clear by
now. Thank you for emphasizing it.

 

.And the FINANCIAL "efficiency" (relating to cost of fuels or to benefits of
possible increases in crop production because of biochar) could also be
calculated, but would be more debated because of differing perceived values.



I am very interested in seeing how that can be worked into programmes that
allow for it. Stove promotion is not necessarily about the economic position
of users. A value proposition has many factors and economic gain is one of
them. A great many stoves in Central Java (the focus area) are used to earn
income - far more than one might think before visiting the place. Cooking
performance and fuel efficiency and fuel flexibility are high on the
decision tree.

 

Regards

Crispin

 

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