[Stoves] Celebrate! First-ever international standard for laboratory testing of cookstoves published.

Crispin Pemberton-Pigott crispinpigott at outlook.com
Thu Jun 28 22:15:10 CDT 2018


Dear Ron

>…I think you are suggesting here in this answer (and below) that there is nothing wrong with the present Chinese approach to pay zero attention to intentionally produced char.  True?

The Chinese approach is to count the char as a secondary product. I think you should review the metrics they use before saying any more. In fact the storage portion of the BST Lab at CAU is where the biochar experiments were being stored during char+soil tests.

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>You leave out that it is not at all easy to provide the energy (not the weight) of that char.  Both are of interest.

The protocols for establishing the energy content of char is well known. Anyone who wants to know it has it tested. The char used above is tested in a GC/MS and a bomb calorimeter.

>Is now and was in the WBT 4.2.3 and earlier versions.  Cites on cheating have not been produced to my knowledge.

Examples of cheating are claiming that a stove (the Quad II) that requires 1.3 kg of fuel to perform a cooking task was rated as using less than half of that mass. The lab is not at fault, the protocol is.  Advertising that a stove “uses 500” or “800” g of fuel to “do something” and inducing customers to invest in that stove in the belief that the figure represents the fuel needed to operate it is false advertising. That is what I mean by “cheating”.

>>The cheat that was with us for so long, claiming as the WBT1.x, 2.x, 3.x and 4.x that a stove did not consume fuel because it emerged from the cooking session in the form of char, is gone, thankfully. Please refer again to the definitions.
>This is erroneous.  Please give the (exact) language anywhere that suggests the "did not consume" .   Please don't ask others to go find something they don't believe exists.

The exact language and its misuse historically was examined in detail by WG1 when drafting the definitions. One claim was that as char was remaining existed at the end, and contained embodied energy, it had not been ‘consumed’. Technically that is correct because it if was a charcoal burning stove, it would be remaining fuel. IN a wood stove it is remaining char. The fuel had been consumed, but the char was not.

Being unable to find an agreeable definition of ‘consumed’ outside its obvious meaning and intent on stopping the cheating when it came to claims about fuel consumption, it was agreed that the quantity of Fuel Fed into the stove was an unchallengeable measurement: either the fuel is fed in or it is not. What happened to it afterwards was a separate matter. See the definition for details.

Conventionally, when analysing larger systems (which are a good place to start) the mass of fuel entering the system is weighed. Some of it drops through gaps in grates and hoppers (mechanical losses), some is partially burned and is thrown out with the ash (mechanical loss), some is incompletely burned as CO, for example (chemical loss) and some may be recovered as coked or charred material (secondary product, or mechanical loss depending on what happens to it). This shows that the mass of fuel fed is unaffected by what the device does with the fuel.

Similarly the heat produced by the fire goes in various directions: into the work load, lost to convection and radiation from the device, up the chimney, heat lost in hot ash, chemical energy lost in various ways: ash formation is endothermic. None of these losses or applications or secondary benefits alters the initial total quantum of energy entering the system which the WBT fuel consumption metric claimed it did. It was a stupid mistake and unfortunately people stuck with it. There have been a lot of negative consequences, particularly for stove models that were designed to get “good numbers” on the WBT.

The use of the Fuel Fed metric eliminates many of the potential misunderstandings or deliberate misrepresentations encountered when using the WBTx.x.

>>That ‘char deducted’ formula that you refer to is an energy calculation that relates to the fraction of energy in the fuel fed that was released (theoretically) during cooking. It no longer refers to the mass of fuel fed, as it once did.

>There is no theoretical release in the equation being used to give a number to allow comparing char-making stoves with those that don't.

Wrong again.  You are conflating two things: one is the formula you like to use known as the “char deducted” energy equation which is used, via estimates and conversions, to report a fuel mass equivalent of the energy theoretically released, separately, during the high power and low power phases of the WBT. That is how the formula works. The result, a mass of fuel equivalent, is not the required mass of fuel that one must feed into the stove to accomplish the task. Whether you make char or not does not change the calculation. The problem is char making stoves were being credited with having not needed the fuel they need to do so. As a result stoves that have a fuel efficiency of 20% are being reported to be as high as 40% or more. That misrepresentation places them on a different performance tier, and act known in mathematics as “cheating”.

The second thing is the provision of a char mass metric or a char energy metric for reporting char produced by whatever process is being analysed. I am not sure why you think the Chinese do not have metrics for this. There are several plants in Hebei province that produce char from biomass.  It is used to make liquid fertiliser, exported to several neighbouring provinces where it is subsidised to farmers by their regional governments. I assure you that those char production processes are monitored carefully for energy and mass.

As for the National cooking and heating stove  standard, the test has a wood-burning phase, and a char burning phase. The fire is allowed to continue long enough to permit retained heat in the stove body “carry on cooking” and the char can burn to the point that the water temperature drops to 95 C, burned either partially or completely. This test and its metrics are not the same as those employed when a device is used deliberately to create char, as well it should, because that is what people do in those two different circumstances. Context is everything.

>All the numbers going into that computation are given and all have been in theist WBTs I know about.  In the Chinese official test procedure, the char is wished away.

On this matter it appears you do not know what you are talking about. Please investigate before comment further. Humility will help.

>>This is a major advance in testing methods. Only the stove testing groups used the erroneous ‘char-deducted’ formula. When searching the literature for some example elsewhere in industry, not a single one could be found because the claim was fundamentally misrepresentative. That has now been cleared up.

>Again a paragraph that makes no sense.  Please give exact language from anywhere on what you are talking about.  I think it is the "denominator equation" - which still exists in the latest ISO version - I think adopted with essentially a unanimous vote of many countries (not individuals).

First, you pretend that a vote for a 140 page document constitutes acceptance of everything in it. Second, inclusion was put to a vote several times and lost because it is indefensible as a novel, proposed calculation method, for which no precedent could be found. Third, the WBT itself is an unpublished, unreviewed document and could not be used as a reference (to itself). It would not pass peer review because it contains so many errors. Fourth, that metric is not in the set of harmonized definitions. Fifth, the “char-deducted” metric is mentioned in the text of the ISO 19867-1 document but not the definitions. You should be asking how it got there, given the overlap between WG1 and WG2.

I see no reason why we should object to an entire complex document because it contains one metric no one might use. If someone tries to use it to make claims for the Fuel Fed, they will no doubt be asked why they are using a non-standard metric without precedent in order to misrepresent the fuel needed to operate the device. Putting something into a document does not make it unanimously accepted any more than a politician claiming that anything they do is accepted by the public, “because they were elected”. Remember Nixon, who said, “When the President does it, that makes it legal.” When an ISO document contains something, that does not make it legitimate.
>>Not a single voice supporting the use of a “WBT-like” test was raised in the ISO process. In fact it was put to a vote in exactly that form, in those words: “WBT-like”. No one wanted it.

>This is a long way from what others have told me occurred.  It would help this list to have your explanation of how you know what to be true.

There is no need. There is no reference in the ISO document to the WBT which is as dead is a door nail. There are a five dozen reasons why the WBT should be ignored. Even boiling water as some tests still do, is fraught with problems because when water is “boiling” is difficult to assess. See here<http://www.sites.hps.cam.ac.uk/boiling/>. Good stove performance tests do not necessarily include boiling water. The Indian national test does not and has not for 26 years.

>>The ISO Standard is not anyone’s standard – it only has meaning when a country adopts it, or adapts it. Any country contemplating adopting this document as a national standard will have to consider how it will be implemented, and whether all of it or some of it will apply. When it comes to things like fuel efficiency, which is important in some regions, it is likely the national standards body will apply its collective mind to what portions of this massive document they will use. As anyone reading it will quickly see, it is unnecessarily complex, and requires numerous pieces of equipment that are very expensive if one is to have a reasonable level of confidence in the result. Because a national standard provides a warranty of performance, it is pointless to have as a test method something that doesn’t provide it.

>I claim none of this paragraph is true.  I have skimmed it;  Crispin says he has not.

You have no idea what you are talking about. I didn’t skim it, I read it. I helped write it. I tried to correct many parts of it. Sometimes I was successful. A major failing is that the test is not equipment-agnostic. This greatly limits the likelihood it will be adopted, as is, at the national level.

>A country that chooses to ignore a work that has taken such effort will lose a lot of credibility in science circles.

It appears you have no idea how international standards are created and applied. I am not holding you responsible for this. None of the US team members had any experience writing international, and as far as I could discern (by asking), national standards.

>This took many years to balance complexity with completeness.

We can leave that judgement to the National Standards Bodies to decide. ISO standards are applicable if a National Standards body adopts it, usually with modifications.

>>People seeking lower cost and more accurate alternatives may consider adapting Indian IS–13152, China’s NB/T 43008 – 2012, or the CSI test method which has been used internationally in some form since 2009.

>I repeat my claim that Crispin has kindly repeated above:   "I can think of no reasonable rationale for such a position."    To report results on a stove designed to make char without measuring the char, because the national standard says so,  is unbelievable.  That couldn't happen if offending countries adopt the new ISO procedure.

You again paint yourself into a corner. You are hoping to create a logical path from char-making to the reporting of a higher fuel efficiency for stoves that produce it, because their low fuel efficiency creates a tier ratings.  You are not the only one to state this plainly. You want to cheat on the fuel consumption metric.

Char making while cooking is a secondary benefit like hot air, space heating, light and any other benefit including drying fuel. There are sensible metrics for reporting such things, and have been for years. What is not useful is to deduct the energy in the char produced and then claim that the fuel needed to create the char was not needed by the stove to perform the primary cooking task. Whether a standard is national or international or a project standard has nothing to do with the simple task of reporting what happened in an honest manner. Char produced should be reported as a mass per not mass of dry fuel, in my view. It should not affect the reporting of the fuel mass needed to operate the stove unless that fuel started off as char (i.e. the same as what comes out).

>>The WBT 4.2.3 contained, when it does, some 75 systematic errors as well as its much-discussed conceptual errors. We do not know yet how many are contained in the ISO-19867-1 because it has not been reviewed conceptually or systematically. Because the test method is novel, (untested) problems with its implementation will have to be resolved at the national adoption level, if it turns out to be acceptable ahead of other options.

>I have asked for this "75" list several times and do so again.   The ISO document that is being discussed has undergone agonizing review - by top experts.

You have never previously asked seeing the list of errors. I would have sent it to you if you had.  I have replied to you separately with a copy of one of the WBT sheets from 2016 attached, the one used in a number of the testing centres around the world. I included in that message the following:

“Note that this is a recent version of the sheet. Originally it had 140 errors.  There are 36 outputs noted as “valid if the char is correctly handled” which of course historically, it has not been. In addition to the 60 systematic errors noted, that brings the total to 96 if the char is deducted from the energy used, and then the result is fed into the fuel consumption metric.”

>>The problems created by the WBT remain, however, as witnessed by the recent release of the second edition of the Micro-gasifier Handbook which makes barley any mention of testing and includes multiple references to ‘performance’ based on the obviously erroneous fuel consumption claims of the WBT.

>How about a specific cite and example quotes?

Please read the microgasifier handbook and look at any of the “efficiency” claims. There is, for example, a chart of stove performance with CO and efficiency numbers plotted against each other. All the efficiency numbers are from fuel mass consumed using the WBT without correction for the char energy error. This chart is in line with the Berkeley-sourced GACC Stove comparison chart where erroneous fuel efficiency number are plotted on a common framework. Missing from that chart are any coal stoves, in spite of the fact that hundreds of millions of poor people around the world use coal for their primary cooking needs. When the performance numbers are corrected, the groupings of stoves changes dramatically, and the advances in science and engineering of the past ten years are manifest. We need a new chart.

>I claim it quite likely that there is zero error in the consumption claims.

Because you have chosen the term “consumption” the ISO working group decided to use a term that more accurately reflects the intention, which is to report the mass of fuel needed in order to complete the cooking task. If you define “consumption” as “was burned” you could be correct, or close to it, but it is not the Fuel Fed. The ISO WG agreed to use Fuel Fed to overcome this fundamental and oft-committed error.

>>For anyone who is new to this topic I recommend reading the CREEC Lab test of the Quad II stove (featured in that Handbook) which shows that the fuel fed per replication of the test is 1.3 kg (as received) and claims a dry wood fuel consumption of 636 g….

>Crispin here totally misses everything possible about char-making stoves.

You have no idea what you are talking about. I have repeatedly said here that there are appropriate metrics for reporting the mass of char produced, and its energy.

>More on this if he wishes and gives cites so we don't waste more time on something agreed upon in the new ISO test procedures.

Please refer to the set of harmonized definitions produced by Working Group 1. It is called “Harmonized” for a reason.

>Measuring char-making capabilities of a cook stove that excels in emissions and other ways is probably a real problem if one is into coal-consuming heating stoves.

Are you trying to impugn the work of thousands of diligent workers bringing better lives and living conditions to the hundreds of millions of people suffering from coal and smoke in Asia? Even for you, that is a scurrilous ad hom comment. If you are not willing to do the groundwork necessary to make useful contributions to the science of performance testing and rating, your level of influence will not rise above its current undetectable level.

This correspondence is sufficiently complete.
Crispin


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