[Stoves] Differences in stove testing

[Traveller]

Crispin, Ron:

About charmaking stoves, I have a most basic question -- what is the
difference between leaving wood on the tree versus leaving it in charred
form, to be used after boiling water? What difference does it make to whom?
We are not talking about coal - leaving it in the ground versus using it or
storing it. Biomass has different features.

Does it not matter whether the wood is from a dead tree or chopped twigs or
plant stalks? Isn't this all about the ideology of "save the trees"? Does
it - or does it not - matter where the biomass is, in what usable form,
with what alternative uses and competing against what fuels for cooking?

You know I don't care for "fuel efficiency" in the abstract. Where the
marginal cost curve for fuel supply is relatively flat, there is no reason
to "save" fuel. This "efficiency" obsession is a relic of the 1970s
"deforestation crisis" - still marketed lucratively by GACC and others --
with two added twists since, namely i) energy efficiency is deified as a
"sustainability" virtue (neglecting that it is the overall resource
efficiency that matters, and it may not be knowable in some circumstances),
and ii) thermal efficiency is assumed to lead to lower rates of PICs
(products of incomplete combustion), which is not uniformly the case
(depends on fuel chemistry and the whole chain of data-free logic).

The intellectual foundations of "efficiency" metric have always been weak.
Context is forgotten. Poor people are sacrificed at the altar of funky
environmentalism.

[Thank you, Frank, for the succinct claim "There is no good value for a
stove for energy efficiency. No reason to go all out for that value." I
think the same of PM2.5 emission rates. If the comparator is LPG, might as
well forget about any and all solid fuel cookstoves; LPG will win on
versatility, control convenience any day and electricity will do better.
It's not as if we discuss economics when we do biomass stoves; we are fond
of declaring LPG as evil and electricity as unaffordable, without bothering
what makes biomass angelic or affordable and how much.]

I agree with Crispin that "fuel efficiency" has a meaning in cookstove
testing that should not be corrupted by "credit for charcoal" IF the
objective is to minimize fuel requirements of one meal at a time.

But this need not always be the case; depends on a host of factors in total
fuel use per family, distance from fuel source, monetized costs,
opportunity costs of collection and storage. As with cooking, traditional
biomass fuel supplies have a rhythm, and such rhythms vary over time and
geographies.

I am sure some people see value in charcoal from home stoves - for own use
or for sale, as in Paul's argument. I remember from my childhood how excess
wood in the stove after the fire was doused was split into charcoal and
uncharred wood for later use. If that use is for later cooking, I agree
with Paul that "fuel efficiency" and "energy efficiency" should be
distinguished and I even agree with Ron that there should be a credit for
charcoal.

Depends on what the objective is. Crispin is absolutely correct on that
point, apart from the merits of WBT - whether it calculates anything right
or whether its calculations are reliable or worth beans.

The most radical aspect of Paul's stoves in West Bengal is that people have
appreciated and accepted the magic ("jadu").

I don't agree with WBT in any form, shape protocol, statistical methods
with some non-descript "biomass" standarized for testing in standardized
conditions that have absolutely no bearing on local fuel quality or local
cooking practices. For decades, stovers have been hung up on the most
sterile, irrelevant aspect of oxidation in a firebox.

I go back to the basic questions - what is the service standard, and what
is the objective? Who decides, why and how.

*******************

If, as Tami Bond has now raised a question about, there are multiple
services - and arguably many more objectives to please the cook than simply
fuel efficiency or PM2.5 emission rates - then the whole IWA logical
framework is worthless. (I also think such reductionist view of cooking,
based on no more than a few year-long studies of fuel economics, chemistry,
and cooking practices is basically immoral. Indeed, I doubt if there is ANY
year-long study with fuel characteristics, cooking practices, efficiencies,
emissions, air chemistry, disease incidence and deaths covering .0001% of
the 3 billion people.

Let me call such a study of 3,000 people a "benchmark" or "reference"
study. I beg of you all to tell me if such reference studies exist, should
exist, or whether this ISO exercise can go on without such studies,
arguably over long enough periods to be able to make any meaningful
predictions of "avoided" premature mortality of current cohorts of PRESUMED
"dirty cooking".

For Kirk Smith and WHO, UNDP, "solid fuel use" is BY DEFINITION dirty and
LPG or electricity is BY DEFINITION clean. Which is in part why Kirk Smith
cautions against what he calls the "natural urge" to regard "attributable"
deaths as "avoidable deaths". IF AND ONLY IF all PM2.5 is equally toxic,
and toxicity of short-term high exposures can be determined in a verifiable
manner to have an impact on mortality and disability at individual level
for current cohorts (probabilistically) the WHO IAQ Guidelines for
Household Fuel Combustion are worth beans.

It amazes me that while epidemiologists keep telling us that the evidence
of stove use and specific disease incidence is spotty and subject to
qualifications, and that the methods of Integrated Exposure Response are
preliminary, and public health experts behinf Global Burden of Disease
assert that they used to get away with murder, why is WHO propagating the
utter nonsense of Emission Rate Targets ans stove Tiers? (I have found many
problems with the few epidemiological studies I have read - e.g., the
Malawi study that found the Phillips stove to be of no use, no matter its
emission rates in practice - and have long experience in other areas of
reading hedged statements in fudged studies being turned into screaming
headlines.)

To me, it is of no relevance that John Mitchell of EPA or "EVERYBODY" Ron
"talked to at the ETHOS conference" agrees on an equation. What are these
"experts" worth for cooking instead of just boiling water in labs? If my
suspicion is borne out - NO "reference study", leave alone representative
ones - why are we arguing on anything?

It is perfectly legitimate to cook careers and grant proposals for the
purposes of saving forests or single-handedly avoid catastrophic climate
change or proving spurious theories of empowerment, then wasting millions
of dollars on fancy dinners at imperial hotels and white houses,
epidemiological studies, whatever. All that is fine, as also simply
stubborn resistance to challenges to rethink, to cook different careers and
grant proposals.  It is not news to me that highly educated, highly
published, highly celebrated experts are less susceptible to new methods of
cooking and new foods than the poor women on whose behalf they claim to
speak.

All that is fine. Do they have the honesty to concede, "We don't know the
service standard and don't care. We don't know what co-products stoves may
have and how they may be valued by the cook. We don't know if our testing
methods would lead to usable stoves. We don't care if our stoves' economics
apply in northeast Nigeria or northeast India or northeast Afghanistan in
the same way. We are only interested in expert solidarity in competition
for recognition and grants, do not want ventilation in our kitchens using
primitive stoves and rather wet green fuel."

If you wish to argue whether an equation will save three billion people,
continue.

Goldman Sachs and Gold Standard quants will sell carbon credits and aDALYs
any which way. There's always gold mine in standards and specifications,
which is why NIST controls the TC-285, an abomination f science.

Prove me wrong, or ask me to shut up.

Nikhil





Message: 3
Date: Sun, 5 Feb 2017 15:37:41 -0700
From: Ronal W. Larson <rongretlarson at comcast.net>
To: Discussion of biomass <stoves at lists.bioenergylists.org>
Subject: Re: [Stoves] Differences in stove testing ---- was Re: ETHOS
        2017 agenda and logistics
Message-ID: <F9551690-EE7F-4EC2-A817-6B9E0C1D071E at comcast.net>
Content-Type: text/plain; charset="utf-8"

List and Crispin:

        The short quotation below won?t be clear to those not following
this debate closely.  It is from my reply message at 9:58 on 31 Jan to Paul
Anderson - in which I went a lot further reporting on the test experts I
talked to at ETHOS - NONE of whom agreed with Crispin on the topic of this
reply - the way to handle char in reporting efficiencies.  The ?John? in
this message is EPA?s John Mitchell, who I feel I can now quote as agreeing
with my interpretation below.  John Mitchell supports the existing
?denominator equation? - as does EVERYBODY I talked to at the ETHOS
conference.  See a small qualifier in this 31 Jan message on misuse of the
results - but those experts still did not find fault with the equation
itself.
.
        Inserts below.


> On Feb 4, 2017, at 9:07 AM, Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:
>
> Dear Ron
>
> ?When you report John saying ?the testing protocols are now with some
adjustments for char-producing and for ash-producing stoves?, this means
that the efficiency number that Crispin prefers (zero credit for charcoal
production; do not use the ?denominator equation?) is there as well as the
one that you and I prefer - which gives partial credit to char production -
via this same ?denominator equation?).?
>
>
> I think you should be very clear about what you want:
>
> You want to increase the cooking efficiency metric number by deducting
the energy content of the recovered char energy, is that correct?

        [RWL1:  I am agreeing with decades of usage to make the ?cooking
efficiency metric number" more accurate.  The ONLY accurate denominator is
one with the char being subtracted - as the ratio is the heat into the cook
pot divided by the total energy that COULD BE available for that measure of
energy into the cookpot.  Energy that is in the char was NOT available to
go into the cookpot.  It HAS to be subtracted to get a valid efficiency
when you are running different tests with relatively arbitrary and
unintentional amounts of char being produced.

        You are the only person I have heard say this is improper.  Your
view has been dismissed by dozens of others - especially in
?official?polling.

        I think the ?denominator equation? formula undervalues (not
overvalues) the energy in the char.  It says the inefficiency is larger
than it is.  I accept  the formula only because the tier structure is based
on its use.  I would have been happier with a tier structure based on
overall efficiency, but I know that is impractical - especially at this
late date.
>
> This deduction raises the reported fuel efficiency.
        [RWL:  For small amounts of char it makes the reported efficiency
more accurate.  It undervalues the overall (more than heat transfer)
efficiency of stoves that are trying to make char.

>
> Are you OK with that as the result?
        [RWL:  Marginally.   Only in the tier heat rating sense.

        Example:   If energy into the boiling water and charcoal each are
one-third, then the sum of all inefficiencies MUST also be one-third.  You
argue for a heat transfer efficiency of 1/3 (dropping all consideration of
the char).  The ?denominator equation? (used by everyone but yourself as
near as I can determine) says the ?heat transfer efficiency? is
(1/3)/(1-1/3) = (1/3) / (2/3) = 1/2.    I can live with this, but I also
think it important to say that the inefficiency is NOT also 1/2.  The
overall efficiency, when one is trying to produce char, is 1/3 +1/3 = 2/3.
This last is clearly NOT the ?heat transfer efficiency?, but the overall
efficiency should be reported as well if we are trying to promote more
valuable stoves, and it is not being reported.

        Now the reverse question -  WHY are YOU so unhappy with the
subtraction in the denominator?  Is it your opinion that this char
production was an inefficiency?    You have expressed great unhappiness
with the ?denominator equation?, but I don?t recall ever seeing a reason.
The purpose of including a char term in the denominator is NOT to say
anything about char - it is to get at the POTENTIAL heat transfer
efficiency.  To repeat - too many will think that char-making stoves are
much less efficient than they really are.

Ron

>
> Thanks for clarifying
> Crispin
*************
------------------------------

Message: 5
Date: Mon, 6 Feb 2017 01:28:12 +0000
From: Crispin Pemberton-Pigott <crispinpigott at outlook.com>
To: Discussion of biomass cooking stoves
        <stoves at lists.bioenergylists.org>
Subject: Re: [Stoves] Differences in stove testing ---- was Re: ETHOS
        2017 agenda and logistics
Message-ID:
        <DM5PR2201MB149906E00A7B40F59925F0B6B1400 at DM5PR2201MB1499.na
mprd22.prod.outlook.com>

Content-Type: text/plain; charset="utf-8"

Dear Ron

??I went a lot further reporting on the test experts I talked to at ETHOS -
NONE of whom agreed with Crispin on the topic of this reply - the way to
handle char in reporting efficiencies.

That provides a comment on the poor understanding of the principles of
engineering and performance rating amount those who you contacted at ETHOS.
It is sad that those how claim to lead are so at sea when it comes to
making such simple determinations. Perhaps you are not aware that the
?char-deducted formula? is unique in the world when reporting the % of fuel
energy delivered as ?work?.

Char making is not ?work? when it comes to cooking energy delivered.

>John Mitchell supports the existing ?denominator equation? - as does
EVERYBODY I talked to at the ETHOS conference.

Ditto ? if true, it is significant that the ETHOS participants you
discussed this with do not follow this list, read about the problems and
understand the implications, or consider that scientific norms should apply
to stove testing.

>[RWL1:  I am agreeing with decades of usage to make the ?cooking
efficiency metric number" more accurate.

The cooking efficiency is the ratio of cooking energy to the energy in the
fuel fed into the stove. Comparing the rating of two stoves calculated on
that basis gives a direct comparison of the fuel consumption to accomplish
a task. More on that below.

>The ONLY accurate denominator is one with the char being subtracted - as
the ratio is the heat into the cook pot divided by the total energy that
COULD BE available for that measure of energy into the cookpot.

That is a description of the heat transfer efficiency. It is unfortunate
you are not learning from this interchange. I have explained in detail how
to calculate the heat transfer efficiency and it starts by deducting the
char energy (all of it, not just some recoverable portion).  You are
calling the heat transfer efficiency the cooking efficiency. That is the
root of the problem. They are different when the stove produces a solid
residue containing unreleased energy.

>Energy that is in the char was NOT available to go into the cookpot.

That is why it is deducted when calculating the heat transfer efficiency.

>It HAS to be subtracted to get a valid efficiency when you are running
different tests with relatively arbitrary and unintentional amounts of char
being produced.

That is correct, if you want to calculate the heat transfer efficiency.

>You are the only person I have heard say this is improper.  Your view has
been dismissed by dozens of others - especially in ?official?polling.

Obviously you are not in all conversations on the matter. You are in no
position to conduct an ?official poll?. Science does not operate on
?official polls? of people whether or not they are informed on the subject.
In fact, opinion counts for little in a mathematical calculation.

>          I think the ?denominator equation? formula undervalues (not
overvalues) the energy in the char.

The equation does not report the cooking efficiency, nor the energy in the
char nor its fraction of the original energy. It is an error to use it for
anything. It has no standard name because it is not accepted as a standard
calculation save as a rough guide to the heat transfer efficiency, which I
remind you was the original intention of the authors of the VITA test. The
approach was used in a much more refined form in the BUCT paper of 1 year
ago. When it was pointed out on this list that the calculation of the
relative fuel consumption was in error because of this, one of the authors,
Kirk Smith, made a comment on this group that the error would be corrected
?if the paper was published?. In fact the paper was already published. The
error is to think that the relative heat transfer efficiencies of two
stoves is the same as the relative fuel consumptions. This error is common
to the WBT (all versions) the CCT and the KPT. (With the KPT it is only
considered in certain circumstances so there is a caveat there ? the KPT
sometimes gives the correct answer.)

>It says the inefficiency is larger than it is.

The formula doesn?t calculate the inefficiency of anything.

> I accept  the formula only because the tier structure is based on its use.

You are correct that the tier structure (which has its own additional
defects) is based on the WBT 4.1.2. which miscalculates the cooking
efficiency. I invite you and everyone else on this list to obtain one of
the (at least) three versions of the WBT 4.1.2 and run a set of
measurements through it to get the ?thermal efficiency?.  Then run the same
set of measurements through v 4.2.3 and see what the answer is. Be amazed.
To get the real answer, delete the contents of the ?char? cell and set the
char catching container to zero. Compare that with the other results. Be
shocked.

>I would have been happier with a tier structure based on overall
efficiency, but I know that is impractical - especially at this late date.

Interesting. So getting the correct answer is not important, expediency is?
How long would you be willing to wait under normal circumstances?

>>This deduction raises the reported fuel efficiency.
>[RWL:  For small amounts of char it makes the reported efficiency more
accurate.

No, it mis-reports the metric that claims to represent the fuel
consumption. The more char you make, the greater the misrepresentation of
the fuel economy.

>It undervalues the overall (more than heat transfer) efficiency of stoves
that are trying to make char.

You are correct on this point insofar as the formula does indeed calculate
the heat transfer efficiency (or a reasonable proxy of it). I am not cure
why you have contradicted your earlier points above.

>>Are you OK with that as the result?
[RWL:  Marginally.   Only in the tier heat rating sense.

So having the wrong answer is not an issue as long as the heat transfer
efficiency tiers are not changed? Did you ever buy a product based on the
heat transfer efficiency?

>Example:   If energy into the boiling water and charcoal each are
one-third, then the sum of all inefficiencies MUST also be one-third.

That is incorrect. Please read on.

>You argue for a heat transfer efficiency of 1/3 (dropping all
consideration of the char).

No, I argue that the cooking efficiency is 1/3. Please correct your
misunderstanding.

>The ?denominator equation? (used by everyone but yourself as near as I can
determine) says the ?heat transfer efficiency? is  (1/3)/(1-1/3) = (1/3) /
(2/3) = 1/2.

First, virtually no one outside the USA uses this formula in any official
capacity (CDM/Gold Standard excepted) , and within the USA it is shunned
for regulatory purposes by the EPA.

Second, that is how to calculate the heat transfer efficiency, not the
cooking efficiency.

>I can live with this, but I also think it important to say that the
inefficiency is NOT also 1/2.

The formula does not calculate an inefficiency, it calculates the heat
transfer efficiency. The heat transfer efficiency is not useful for
calculating fuel savings.

>The overall efficiency, when one is trying to produce char, is 1/3 +1/3 =
2/3.  This last is clearly NOT the ?heat transfer efficiency?

Correct. It is not the heat transfer efficiency. It does not have a name as
you are adding the cooking efficiency to the % of energy in the original
fuel that was not burned. As I pointed out to you and Paul, this metric is
non-standard and does not have a name.

>but the overall efficiency should be reported as well if we are trying to
promote more valuable stoves, and it is not being reported.

What do you consider to be the ?overall efficiency??

>Now the reverse question -  WHY are YOU so unhappy with the subtraction in
the denominator?

Because as applied in the WBT (all versions) it gives a misleading number
which is used to calculate the relative fuel savings of stoves, comparing
them with a baseline product. It gives the wrong answer. You indicated
above that while the cooking efficiency is 1/3 and the WBT reports it to be
?, you are OK with that misrepresentation. I am not.

>Is it your opinion that this char production was an inefficiency?

In standard terms char production is reported as a % of the dry fuel input.
Where it is not a desired product, it is a mechanical loss.

>You have expressed great unhappiness with the ?denominator equation?, but
I don?t recall ever seeing a reason.

Then you have not been reading my posts.

>The purpose of including a char term in the denominator is NOT to say
anything about char - it is to get at the POTENTIAL heat transfer
efficiency.

There is no such metric as the ?potential heat transfer efficiency? except
to say that it is always 100%, until the stove is tested.

>To repeat - too many will think that char-making stoves are much less
efficient than they really are.

When it comes to fuel efficiency, char making stoves are usually much less
fuel-efficient than stoves that burn all the char. As usual, you are
looking for some way to over-report the fuel efficiency by pretending the
char is unburned ?fuel?.

Then, you plan to bury the char in the ground (proving it was not ?fuel?
after all) to accomplish what others call ?sequestering carbon?.

Using your example above:

Cooking efficiency: 1/3
Char energy retention, based on the recoverable mass of the solid residue:
1/3
Heat transfer efficiency: 2/3

Two stoves both have a cooking efficiency of 1/3. One of them makes some
measurable amount of char. Applying the WBT formula raises the reported
cooking efficiency (not the actual cooking efficiency). The actual cooking
efficiency shows that both stoves require exactly same amount of raw fuel
to cook. Applying the WBT formula one finds that the char-making stove is
claimed to require less fuel to complete the cooking task.

That claim is false. People are being induced to pay for a reduction in
fuel use on the basis of the WBT calculation. They are being defrauded with
false claims of fuel saving. I don?t believe you are ?OK? with this
situation.

Regards
Crispin

------------------------------

Message: 6
Date: Sun, 5 Feb 2017 20:22:02 -0800
From: Frank Shields <franke at cruzio.com>
To: Discussion of biomass cooking stoves
        <stoves at lists.bioenergylists.org>
Subject: [Stoves] Energy efficiency value
Message-ID: <CEB7902A-68E6-46E6-8A27-61193EB0EED7 at cruzio.com>
Content-Type: text/plain; charset=utf-8

Dear Stovers,

Why is knowing the energy efficiency so important?

If we were to take a tin metal stove and provide a controlled heat source
(oxygen-acetaline) and measure the energy efficiency at different, steady
powers (say 1/4th, 1/2, 3/4 and full power) using the WBT as indicator this
would not likely be a straight line - I am thinking. Then take a well
insulated clay stove and the four points would likely be more of a straight
line but all stoves would have a different curve.

Now add a controlled fuel like propane (with no O2 source) and now you add
to the variables primary air and secondary air. Then switch the test to
using biomass and more variables are added.

I?m thinking without a straight (or at least predicted) curve for the four
power settings regarding energy efficiency that the test is meaningless.
There is no good value for a stove for energy efficiency. No reason to go
all out for that value.

I?m thinking a better approach is Fuel Classification vs Heat into the Pot.
I think using a single type of biomass fuel we can predict the time it
takes to boil the water. Use another type of fuel and it takes a little
longer - every time.  The difference is not the energy in the biomass but
more the Classification we give to the biomass. (still needing
development). We test success using Cecil approach to find out how well it
works - but know from lab study the biomass properties so to be able to
compare and predict success in different locations.

Regards

Frank








Thanks

Frank
Frank Shields
Gabilan Laboratory
Keith Day Company, Inc.
1091 Madison Lane
Salinas, CA  93907
(831) 246-0417 cell
(831) 771-0126 office
fShields at keithdaycompany.com



franke at cruzio.com



---------
(India +91) 909 995 2080 <+91%2090999%2052080>
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