[Stoves] Stove Definition - controllability

Fri May 3 19:31:30 CDT 2013

Josh,

Thanks so much for that paper dealing with peanut shell biochar. This is a
good example of the kind of research needed in giving value to peanut shell
biochar. In this study we see that the efficacy of peanut shell biochar for
removing TCE from water was comparable to that of activated carbon.
Activated carbon sells at a relatively high price, and now peanut shell
biochar can be used in place of this expensive commodity.

So let us imagine a small village in a developing country where peanuts are
grown. Along comes a company that installs a pellet machine and produces
peanut shell pellets. These pellets are given to household free-of-charge
in exchange for some of the biochar produced from these pellets. The
company does not have to set up a large kiln to make peanut shell biochar.
It only has to set up a pellet machine.

So in using a cook stove, a household has a gas that can be used in the
place of bottled gas, and it has a biochar that can be used in the place of
activated carbon.

Here in the highland area of Vietnam where I live, there are a lot of pine
trees. Minority people regularly chop down these trees to make charcoal,
leading to high levels of deforestation.  Here again pellet machines could
be installed to make pine needle pellets that, when processed in cook
stoves, could easily take care of all household cooking needs. At the same
time, pine needle biochar has certain properties that rival those of
activated carbon.

We look far too much at the cook stove. We need to focus a lot more on fuel
preparation and biochar research.

Many thanks.
Paul

On Fri, May 3, 2013 at 8:13 PM, Josh Kearns <yeah.yeah.right.on at gmail.com>
wrote:
>
> Effects of pyrolysis temperature on soybean stover- and peanut
shell-derived biochar properties and TCE adsorption in water
> Author(s): Ahmad, M (Ahmad, Mahtab)[ 1 ] ; Lee, SS (Lee, Sang Soo)[ 1 ] ;
Dou, XM (Dou, Xiaomin)[ 2 ] ; Mohan, D (Mohan, Dinesh)[ 3 ] ; Sung, JK
(Sung, Jwa-Kyung)[ 4] ; Yang, JE (Yang, Jae E.)[ 1 ] ; Ok, YS (Ok, Yong
Sik)[ 1 ]
> Source: BIORESOURCE TECHNOLOGY  Volume: 118   Pages: 536-544   DOI:
10.1016/j.biortech.2012.05.042   Published: AUG 2012
>
> Abstract: Conversion of crop residues into biochars (BCs) via pyrolysis
is beneficial to environment compared to their direct combustion in
agricultural field. Biochars developed from soybean stover at 300 and 700
degrees C (S-BC300 and S-BC700, respectively) and peanut shells at 300 and
700 degrees C (P-BC300 and P-BC700, respectively) were used for the removal
of trichloroethylene (ICE) from water. Batch adsorption experiments showed
that the TCE adsorption was strongly dependent on the BCs properties.
Linear relationships were obtained between sorption parameters (K-M and
S-M)and molar elemental ratios as well as surface area of the BCs. The high
adsorption capacity of BCs produced at 700 degrees C was attributed to
their high aromaticity and low polarity. The efficacy of S-BC700 and
P-BC700 for removing TCE from water was comparable to that of activated
carbon (AC). Pyrolysis temperature influencing the BC properties was a
critical factor to assess the removal efficiency of ICE from water. (C)
2012 Elsevier Ltd. All rights reserved.
>
>
> On Fri, May 3, 2013 at 12:45 AM, Paul Olivier <paul.olivier at esrla.com>
wrote:
>>
>> Crispin,
>>
>> I agree: it is hard to cook without controlling heat. Your call for a
level of control from 100% to 25% sounds reasonable.
>>
>> Let us take the example of someone using a direct combustion wood stove.
This person might start out at 25% and add on more wood to achieve 100%.
But it will take time to reach 100%, and it will also take time to reduce
heat back down to the original starting point of 25%, if need be.
>>
>> So it's not simply a question of being able to vary the amount of heat.
The more difficult question is how quickly and easily one can move to any
percentage point in between 25% and 100% heat.
>>
>> Trying to establish criteria by which to judge and compare stoves is
awfully complex. For example, so much depends on the type of fuel that is
available in a given area. The perfect stove might demand a perfect fuel,
and if this perfect fuel does not exist in a given area, one has to choose
from an array of imperfect stoves. The perfect stove might be too expensive
for a particular poor corner of our planet. So once again we have to choose
from an array of cheap and imperfect stoves.
>>
>> Funding agencies come along and demand criteria by which to judge
stoves. But I profoundly mistrust the role of funding agencies. They, with
massive inputs of capital from the outside, can easily distort the normal
evolution of cook stove technology in a given area. Many funding agencies,
for example, have come into Vietnam and dispensed 100's of millions of
dollars in areas other than cook stoves. At the end of the day, many of
them have accomplished virtually nothing.
>>
>> So I suggest that we should approach funding agencies with caution. In
my opinion, it's not so much the cook stove that needs funding. It's all
that comes before and after the cook stove. Fuel preparation needs funding
(the before), and biochar research needs funding (the after).
>>
>> Someone recently took one of my gasifier into Laos. In this area of
Laos, she noted an abundance of peanut shells. But due to its low bulk
density, the peanut shell has to be pelleted before it can be used as fuel
in my gasifier. At the same time, no one has done research on the
properties of peanut shell biochar.
>>
>> Funding agencies could subsidize, through affordable loans, the purchase
of pellet machines at the village level, and based on several scientific
studies they might conduct, they could point to the benefits of peanut
shell biochar when incorporated into the soil. The big priority in this
particular region of Laos is not the stove, but all that comes before and
after it.
>>
>> How easy it is to get exceptional results out of a stove, if the fuel is
uniform and predictable, and how easy it is for a poor family to pay for a
stove, if this family can sell or use the biochar it produces.
>>
>> Thanks.
>> Paul
>>
>>
>>
>>
>> On Fri, May 3, 2013 at 9:12 AM, Crispin Pemberton-Pigott <
crispinpigott at gmail.com> wrote:
>>>
>>> Dear Friends
>>>
>>>
>>>
>>> I would like to remind everyone that it is pretty important to a cook
to be able to control the fire in some manner. There are lots of precedents
so I won’t repeat them. I would like to have a minimum control exerted over
the cooking power in order to qualify as a ‘cooking stove’. There are many
appliances which are used for heating water, showers (like the Geyser 2000
etc) or drying fish and so one and on. But in order to ‘cook’ the fire has
to be controllable.
>>>
>>>
>>>
>>> For an electric or gas stove this is fairly easy. In order to start
things off, what does everyone think about a turn down ration of 4:1 where
the turn down is ‘willful’ meaning it is controlled by the cook be either
removing fuel, controlling airflow or by some other means. The reason is
that stoves are appearing which definitely burn fuel and provide heat but
are not very controllable (or not at all controllable). While one car argue
that by brilliantly fuelling the stove in just the right manner a fire and
its burn can be exactly matched to a cooking need – agreed this is possible
– but is it ‘cooking’?
>>>
>>>
>>>
>>> When sitting in the field with cooks it becomes obvious that most
cooking involves controlling the power at some point. How much control
should be applicable to a stove in order to qualify as a ‘cooking stove’?
>>>
>>>
>>>
>>> If I ask for a water heating stove, it would not have to have any
controllability at all – it just needs to heat the water within a certain
time after which it can go out – no one will mind. But if we want to
present a ‘solution’ (a cooking alternative to an open fire or sheltered
fire) it will have to be manageable ‘to a certain extent’.
>>>
>>>
>>>
>>> Thus if someone says, “Here is my new cooking stove,” I can say, “Prove
it can cook.”
>>>
>>>
>>>
>>> If I ask for a maximum power of X and ask for a demonstration that it
can be controlled to X/4 is that reasonable as a minimum standard of proof?
>>>
>>>
>>>
>>> Thanks
>>> Crispin
>>>
>>>
>>>
>>>
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>>>
>>
>>
>>
>> --
>> Paul A. Olivier PhD
>> 26/5 Phu Dong Thien Vuong
>> Dalat
>> Vietnam
>>
>> Louisiana telephone: 1-337-447-4124 (rings Vietnam)
>> Mobile: 090-694-1573 (in Vietnam)
>> Skype address: Xpolivier
>> http://www.esrla.com/
>>
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>>
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>>
>>
>
>
>
> --
> Josh Kearns
> PhD Candidate, Environmental Engineering
> University of Colorado-Boulder
> Visiting Researcher, North Carolina State University
>
> Director of Science
> Aqueous Solutions
> www.aqsolutions.org
>
> Mobile: 720 989 3959
> Skype: joshkearns
>
>
>
>
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>
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>
>

--
Paul A. Olivier PhD
26/5 Phu Dong Thien Vuong
Dalat
Vietnam

Louisiana telephone: 1-337-447-4124 (rings Vietnam)
Mobile: 090-694-1573 (in Vietnam)
Skype address: Xpolivier
http://www.esrla.com/
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