<div dir="ltr">Crispin, Ron: <br><br>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. <br><br>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? <br><br>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). <br><br>The intellectual foundations of "efficiency" metric have always been weak. Context is forgotten. Poor people are sacrificed at the altar of funky environmentalism. <br><br>[Thank you, Frank, for the succinct claim "<span style="color:rgb(0,0,0)">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.]<br></span><br>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.<div><br></div><div>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. <br><br>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. <br><br>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.<br><br>The most radical aspect of Paul's stoves in West Bengal is that people have appreciated and accepted the magic ("jadu"). <br><br>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. <div><br>I go back to the basic questions - what is the service standard, and what is the objective? Who decides, why and how. </div><div><br></div><div>*******************<br><br>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. <br><br>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". <br><br>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. <br><br>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.)</div><div><br></div><div>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?<br><br>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. <br><br>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." <br><br>If you wish to argue whether an equation will save three billion people, continue. <br><br>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.<br><br>Prove me wrong, or ask me to shut up. <br><br>Nikhil</div><div><br></div><div><br></div><div><br><br><br></div><div><span style="color:rgb(0,0,0)">Message: 3</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Date: Sun, 5 Feb 2017 15:37:41 -0700</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">From: Ronal W. Larson <</span><a href="mailto:rongretlarson@comcast.net" style="text-decoration:none" target="_blank">rongretlarson@comcast.net</a><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">To: Discussion of biomass <</span><a href="mailto:stoves@lists.bioenergylists.org" style="text-decoration:none" target="_blank">stoves@lists.bioenergylists.o<wbr>rg</a><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Subject: Re: [Stoves] Differences in stove testing ---- was Re: ETHOS</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> 2017 agenda and logistics</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Message-ID: <</span><a href="mailto:F9551690-EE7F-4EC2-A817-6B9E0C1D071E@comcast.net" style="text-decoration:none" target="_blank">F9551690-EE7F-4EC2-A817-6B9E0<wbr>C1D071E@comcast.net</a><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Content-Type: text/plain; charset="utf-8"</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">List and Crispin:</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> 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.</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">.</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> Inserts below.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">> On Feb 4, 2017, at 9:07 AM, Crispin Pemberton-Pigott <</span><a href="mailto:crispinpigott@outlook.com" style="text-decoration:none" target="_blank">crispinpigott@outlook.com</a><span style="color:rgb(0,0,0)">> wrote:</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">> Dear Ron</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">> ?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?).?</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">> I think you should be very clear about what you want:</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">> You want to increase the cooking efficiency metric number by deducting the energy content of the recovered char energy, is that correct?</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> [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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> 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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> 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.</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">> This deduction raises the reported fuel efficiency.</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> [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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">> Are you OK with that as the result?</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> [RWL: Marginally. Only in the tier heat rating sense.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> 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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> 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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Ron</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">> Thanks for clarifying</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">> Crispin </span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">************* </span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">------------------------------</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Message: 5</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Date: Mon, 6 Feb 2017 01:28:12 +0000</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">From: Crispin Pemberton-Pigott <</span><a href="mailto:crispinpigott@outlook.com" style="text-decoration:none" target="_blank">crispinpigott@outlook.com</a><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">To: Discussion of biomass cooking stoves</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> <</span><a href="mailto:stoves@lists.bioenergylists.org" style="text-decoration:none" target="_blank">stoves@lists.bioenergylists.o<wbr>rg</a><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Subject: Re: [Stoves] Differences in stove testing ---- was Re: ETHOS</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> 2017 agenda and logistics</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Message-ID:</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> <</span><a href="mailto:DM5PR2201MB149906E00A7B40F59925F0B6B1400@DM5PR2201MB1499.namprd22.prod.outlook.com" style="text-decoration:none" target="_blank">DM5PR2201MB149906E00A7B40F599<wbr>25F0B6B1400@DM5PR2201MB1499.na<wbr>mprd22.prod.outlook.com</a><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Content-Type: text/plain; charset="utf-8"</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Dear Ron</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">??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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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?.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Char making is not ?work? when it comes to cooking energy delivered.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>John Mitchell supports the existing ?denominator equation? - as does EVERYBODY I talked to at the ETHOS conference.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>[RWL1: I am agreeing with decades of usage to make the ?cooking efficiency metric number" more accurate.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>Energy that is in the char was NOT available to go into the cookpot.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">That is why it is deducted when calculating the heat transfer efficiency.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">That is correct, if you want to calculate the heat transfer efficiency.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">> I think the ?denominator equation? formula undervalues (not overvalues) the energy in the char.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.)</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>It says the inefficiency is larger than it is.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">The formula doesn?t calculate the inefficiency of anything.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">> I accept the formula only because the tier structure is based on its use.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>I would have been happier with a tier structure based on overall efficiency, but I know that is impractical - especially at this late date.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Interesting. So getting the correct answer is not important, expediency is? How long would you be willing to wait under normal circumstances?</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>>This deduction raises the reported fuel efficiency.</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>[RWL: For small amounts of char it makes the reported efficiency more accurate.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>It undervalues the overall (more than heat transfer) efficiency of stoves that are trying to make char.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>>Are you OK with that as the result?</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">[RWL: Marginally. Only in the tier heat rating sense.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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?</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>Example: If energy into the boiling water and charcoal each are one-third, then the sum of all inefficiencies MUST also be one-third.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">That is incorrect. Please read on.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>You argue for a heat transfer efficiency of 1/3 (dropping all consideration of the char).</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">No, I argue that the cooking efficiency is 1/3. Please correct your misunderstanding.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Second, that is how to calculate the heat transfer efficiency, not the cooking efficiency.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>I can live with this, but I also think it important to say that the inefficiency is NOT also 1/2.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">The formula does not calculate an inefficiency, it calculates the heat transfer efficiency. The heat transfer efficiency is not useful for calculating fuel savings.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>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?</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>but the overall efficiency should be reported as well if we are trying to promote more valuable stoves, and it is not being reported.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">What do you consider to be the ?overall efficiency??</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>Now the reverse question - WHY are YOU so unhappy with the subtraction in the denominator?</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>Is it your opinion that this char production was an inefficiency?</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>You have expressed great unhappiness with the ?denominator equation?, but I don?t recall ever seeing a reason.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Then you have not been reading my posts.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">There is no such metric as the ?potential heat transfer efficiency? except to say that it is always 100%, until the stove is tested.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">>To repeat - too many will think that char-making stoves are much less efficient than they really are.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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?.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Then, you plan to bury the char in the ground (proving it was not ?fuel? after all) to accomplish what others call ?sequestering carbon?.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Using your example above:</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Cooking efficiency: 1/3</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Char energy retention, based on the recoverable mass of the solid residue: 1/3</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Heat transfer efficiency: 2/3</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Regards</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Crispin</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">------------------------------</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Message: 6</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Date: Sun, 5 Feb 2017 20:22:02 -0800</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">From: Frank Shields <</span><a href="mailto:franke@cruzio.com" style="text-decoration:none" target="_blank">franke@cruzio.com</a><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">To: Discussion of biomass cooking stoves</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"> <</span><a href="mailto:stoves@lists.bioenergylists.org" style="text-decoration:none" target="_blank">stoves@lists.bioenergylists.o<wbr>rg</a><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Subject: [Stoves] Energy efficiency value</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Message-ID: <</span><a href="mailto:CEB7902A-68E6-46E6-8A27-61193EB0EED7@cruzio.com" style="text-decoration:none" target="_blank">CEB7902A-68E6-46E6-8A27-61193<wbr>EB0EED7@cruzio.com</a><span style="color:rgb(0,0,0)">></span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Content-Type: text/plain; charset=utf-8</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Dear Stovers,</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Why is knowing the energy efficiency so important?</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">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.</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Regards</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Frank</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Thanks</span><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Frank</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Frank Shields</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Gabilan Laboratory</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Keith Day Company, Inc.</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">1091 Madison Lane</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)">Salinas, CA 93907</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"><a href="tel:(831)%20246-0417" value="+18312460417" target="_blank">(831) 246-0417</a> cell</span><br style="color:rgb(0,0,0)"><span style="color:rgb(0,0,0)"><a href="tel:(831)%20771-0126" value="+18317710126" target="_blank">(831) 771-0126</a> office</span><br style="color:rgb(0,0,0)"><a href="mailto:fShields@keithdaycompany.com" style="text-decoration:none" target="_blank">fShields@keithdaycompany.com</a><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><a href="mailto:franke@cruzio.com" style="text-decoration:none" target="_blank">franke@cruzio.com</a><br style="color:rgb(0,0,0)"><br style="color:rgb(0,0,0)"><br clear="all"><div><div class="m_300281158148404652gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div dir="ltr"><div dir="ltr"><span style="font-family:georgia,serif;font-size:12.8px"><br>--------- </span></div><div style="font-size:12.8px"><span style="font-family:georgia,serif;font-size:12.8px">(India <a href="tel:+91%2090999%2052080" value="+919099952080" target="_blank">+91) 909 995 2080</a></span><font face="georgia, serif"><br><i> </i></font></div></div></div></div></div></div></div></div></div>
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