[Stoves] Test methods for cook stoves

Wed Mar 18 14:33:29 CDT 2015

Dear Frank

You say "We have (MUST have) control over the biomass and task if we ever
want to have a stove test that can be sent to any qualified lab in the World
and come back with all the same results." We want to test stoves, not labs!
Labs should be able to be given a protocol and reproduce the same result
within reasonable limits.  That's what labs are good at. 

I thought we were trying to get a better stove - not a better test - and to
find out if one stove performs better than another in a given duty.  So the
first problem is to define the duty, and that is almost entirely set by the
user - he/she defines the fuel and what needs to be cooked.  The fuel and
what needs to be cooked will vary greatly from place to place.  Then you
need some agreed metrics to measure the stove's performance in that duty.
Finally you can get to decide if one stove is better than another in that
duty. Of course, there are a host of duties - different parts of the world
really are different.

So what metrics do we use to measure whether one stove is better than
another?  We could use the amount of fuel consumed in the chosen duty, but
then we have to ask if the user is really interested in the quantity of
fuel.  The work that I have done suggests that it doesn't rank very high -
once you get to a reasonable level of fuel use, the user is happy.  We could
use ease of use, but that is really difficult to measure, because the cooks
learn the tricks of the trade as they grow accustomed to a fuel/stove
combination.  The one metric that the users really seem to value is whether
a stove burns the user's choice of fuel more cleanly than another stove.  If
it isn't very "clean" (however that is defined) then it is likely to taint
the food being cooked.  The cleaner the burn, the less the unwelcome flavour
(although sometimes the flavour is welcomed - think smoked salmon).  

And with "clean" as the metric, there IS something on which the
international community seems to agree. Emissions from stoves are fingered
by organisations like the World Health Organization as having an adverse
impact on people's lives - indeed, on their life expectancy.  So cleaner
stoves is not merely my target - it underpins the whole rationale for the
Global Alliance, for instance.  We must not be diverted into things like the
Clean Development Mechanism, whose primary target is carbon, a doubtful
candidate for a pollutant when you consider how essential the stuff is to
life.  Indeed, history seems likely to view the US court's labeling of
carbon as a pollutant as one of this generation's more unlikely aberrations,
sort of like the belief in slavery 200 years ago.

Hope that helps clarify things.

Kind regards

Philip 

From: Stoves [mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of
Frank Shields
Sent: 17 March 2015 08:09
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Test methods for cook stoves

Dear Philip,

see below

On Mar 16, 2015, at 11:15 PM, Philip Lloyd <plloyd at mweb.co.za> wrote:

Dear Frank

You say "There are two we are interested in when picking out a stove. (a)
biomass / task and (b) time / task"

I beg to differ.  We have little choice of biomass or task - both are almost
entirely determined by the user. Then the important variable is NOT the time
for a task, but the emissions during the (pre-determined) tasks. Granted,
the shorter the time the lower the emissions are likely to be, but that
doesn't necessarily follow.

We have (MUST have) control over the biomass and task if we ever want to
have a stove test that can be sent to any qualified lab in the World and
come back with all the same results. We will continue getting nowhere, as we
have for the past ten years and continue to do so, until the basics of
method development is followed. That is, keep one variable and control all
the others so to notice changes in the one we target. We are just piling on
variables like there is no tomorrow.  

Our target is cleaner cookstoves, fully accepted by users.  I cannot follow
your logic in suggesting that our choice of biomass/fuel and our choice of
task can be at all relevant to achieving that target.

YOUR target is cleaner cookstoves. The person designing the legs for the
stove has a target of making the stove more stable and the person inspecting
the paint job has a target of making the stove look nice. 

Emissions is no more important than the paint job because neither stove will
make it to market until those (and all) Conditions have been met. 

Kind regards

Prof Philip Lloyd

Energy Institute

Cape Peninsula University of Technology

PO Box 652, Cape Town 8000

Tel:021 460 4216

Fax:021 460 3828

Cell: 083 441 5247

From: Stoves [ <mailto:stoves-bounces at lists.bioenergylists.org>
mailto:stoves-bounces at lists.bioenergylists.org] On Behalf Of Frank Shields
Sent: 17 March 2015 06:52
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] Test methods for cook stoves

Greetings Stovers,

My suggestions:

Test methods for comparing Stoves.

1)   The units of interest: There are two we are interested in when picking
out a stove. (a) biomass / task and (b) time / task

2)   Variable = the Stove. We swap out different stoves, run the test and
compare the results for biomass per task and time per task.

3)   Controls; there are two: (a) fuel at one end and (b) task at the other.

Control (a) Fuel

We walk up to the stockpile of fuel in town that has been gathered and piled
and pull out what we want.  If we want to test a Rocket Stove using 2.5cm X
2.5cm X 10 cm long kiln dried sticks we pull out the bigger pieces and have
them sawed and dried.  The rest of the pile we carry back to the forest and
scatter around under the trees.  Paul for his TLUD needs uniform pieces to
keep an even flame front so he takes out what he wants, chips them to size,
and screens out the fines.  The fines and overs are carried back to the
forest and scattered.  Richard collects the material he can turn to mush and
sends the rest back.  Stoves using pellets and sticks are done the same.
Use whatever you want as long as it comes from the pile.

Control (b) Task

The task chosen must have a clear end point.  The start is easy - it's when
the match is struck.

Everything else is NOT part of the test.  Our goal is to reduce by
elimination variables and get control over the ones left so the test can be
conducted at any lab and all will come out with the same results.

We don't care about the chemistry of the gases, smoke, 2.5 pm, stability of
the stove, toxic chemicals, hot surfaces that can burn, or anything else.
If Stove A works better than Stove B then check the gases, make some
adjustments and have Stove B re-tested. If, for example, Stove A completes a
task using less biomass and in a shorter time than Stove B but stove A
produces a lot of smoke - then Stove A wins.

Everything else are 'Conditions' that must be meet.  There are lots of them:
paint streaked with runs on new stoves produced is a condition unacceptable,
poor welds, toxic galvanized metals, poor quality metal - all conditions
unacceptable.  Smoke, toxic gases, hot surfaces or unstable are all
conditions unacceptable.  Too heavy to move or won't take my favorite pot
are more conditions.  But these have nothing to do with the Test. We need to
keep the Test real simple.  All the Conditions in the list must pass or
don't bother doing The Test OR make corrections before testing.

Also;

Control (a) Fuel; we are interested in mass of the biomass used but we can
normalize it to energy for convenience and when comparing 'like fuels' when
the on-site fuels are not available.  When measuring energy I fully agree
with the method Dean used at Stove Camp. The problem is there are so many
unknowns and guesses of the energy content of the different parts of the
fuel.  Perhaps its possible to get good precision (replicates) but I can't
see how the accuracy (real value) could even be close. Therefore, without
knowing of a better replacement, I believe the E450v energy value for the
fuel is the best one to use because it is easier to determine.  I realize
E450v has its own limitations.

Regards

Frank

(retired)   

Frank Shields
 <mailto:franke at cruzio.com> franke at cruzio.com

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