[Stoves] Stove Definition - controllability

[Paul Olivier]

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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