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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><subject changed><o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Dear Crispin, Ron and all,<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>I think we are all in agreement with Crispin the final purpose is to save trees and to Ron it’s important to place a value on the char left over. The question is: How do we determine this?<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>To measure the trees saved:<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>You suggest we determine the wood used for each burn and after several burns we have the average wet wood used. That will work BUT this is an on-site test. It will take many Runs (I suggest ~ten statistically?) for a stove to determine the amount of wood used. And then we go to the next house and how many more houses, all using the same stove (the variable), to come up with a statistical value. Then we give all these same houses a different stove for testing. Is this your plan? <o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>A lab test using fuel Energy as a proxy reduces the variables such that a lot of tests can be done in a short time at a reasonable cost. Like was done before. The biggest variable is the left over energy after the WBT ended and this can be accurately done using a calorimeter on a dried and ground sample –as done at Aprovecho OR my past suggested E450c method. <o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>As for the value to be placed on the char left over: The quality of this char ranges from toxic to plants –to- sucking up nitrogen –to- adding heavy metals –to- producing a large plant and doubling production. To place a value one needs to collect a quantity and determine its value –if any for a purpose. This can all be done per stove following the lab tests above. Lots of tests – I do them all the time. Once the char is separated from the torrefied wood and biomass we need to determine its quality. We need H/C ratio, ash, plant toxicity and the like. A value can then be placed as a separate subject unrelated to the value of the stove. For marketing we may be able to state that stove such-and-such consistently puts out a char of quality to improve soils, sequester carbon or can be used for char cookers -after collecting a composite of the char from a stove and testing it. To add this value to the stove efficiency formula is just adding another big variable and we have too many as it is (un-burned fuel). We need to reduce and control variable. So any value given to char left should be restricted to marketing a stove –as I see it. <o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Thanks<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'>Frank<o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"'>Frank Shields<o:p></o:p></span></b></p><p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"'>Control Laboratories; Inc.<o:p></o:p></span></b></p><p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"'>42 Hangar Way<o:p></o:p></span></b></p><p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"'>Watsonville, CA 95076<o:p></o:p></span></b></p><p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"'>(831) 724-5422 tel<o:p></o:p></span></b></p><p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"'>(831) 724-3188 fax<o:p></o:p></span></b></p><p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"'>frank@biocharlab.com<o:p></o:p></span></b></p><p class=MsoNormal><b><span style='font-family:"Calibri","sans-serif"'>www.controllabs.com<o:p></o:p></span></b></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'> <o:p></o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-family:"Calibri","sans-serif"'><o:p> </o:p></span></p><div><div style='border:none;border-top:solid #B5C4DF 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'>From:</span></b><span style='font-size:10.0pt;font-family:"Tahoma","sans-serif"'> Stoves [mailto:stoves-bounces@lists.bioenergylists.org] <b>On Behalf Of </b>Crispin Pembert-Pigott<br><b>Sent:</b> Monday, February 24, 2014 8:10 AM<br><b>To:</b> 'Discussion of biomass cooking stoves'<br><b>Subject:</b> Re: [Stoves] Request for technology proposals - Clean Stove Initiative, Indonesia<o:p></o:p></span></p></div></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Dear Ron<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>This is getting complicated and the definitions are not completely in alignment so rather than bore people with endlessly inserting them into statements, I will try to re-organise everything for plainer reading. If any misunderstandings are cleared up at het same time, so much the better.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Last point first:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Sustainablility of biomass is defined by the UNFCCC and the current rating for all of Indonesia is that biomass is sustainable. I don’t create ratings, I just read them. There is no CDM funding available for projects ‘conserving biomass’ in Indonesia because the supply is considered to be sustainable. It happens that in Central Java there is a fully sustainable supply of biomass available for domestic cooking and industries. In fact large quantities of biomass are burned (Kaliandra for example) just to get rid of it.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Energy equations: It will be helpful for the casual reader to know ‘what you are up to’ so to speak with this char making stove thing so from my perspective, if I may, I will state it as follows: There is a desire to have the energy remaining of the form of unburned char resulting from a fire credited in some manner so as to reduce the rated fuel consumption of the stove. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>There is no dispute between us whatsoever as to the energy consumption: the energy remaining in the char represents energy not liberated from the fuel consumed. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The important question is not what we want, but what the customer of the test result wants. They are not asking how much energy was used when cooking, they asked how much fuel was consumed. The answer is of course different if there is char remaining and that char is not ‘fuel’ to the same stove for the next fire.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>With a stick burning stove, sticks left over can be used in the next fire and they are counted as ‘not consumed’. No problem, and they are fuel sticks that can be used ‘next time’. Char is not, when it comes to TLUD-char making gasifiers or pyrolysers. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Energy balance with respect to the fuel and the fire:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>A - Energy in the fuel put into the stove<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>B - Energy liberated by the fire<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>C - Energy lost due to incomplete combustion of gases and particles<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>D - Energy remaining in char that is recoverable<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>E - Energy remaining in char and ash that is not recoverable. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>F - Energy in fuel remaining that can be burned in the same stove during the next fire.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>A is calculated on the basis of the fuel ‘as received (AR) which means considering the heat content factored for moisture.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>B is calculated by deduction as it is not directly measurable. In a clean burning stove it will be more than 99% of the heat available from the combusted material.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>C is determined by gas mass and composition and particle mass and its composition). In a clean stove the CO will dominate the value and the total value will be small.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>D is determined by mass and bomb calorimeter or guessing a value. The heat content of char is highly variable and guessing has not been shown to give meaningfully accurate numbers. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>E can be determined by bomb calorimeter.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>F can be determined by bomb calorimeter though the CSI-WBT avoids needing to measure it each time by recycling the leftover fuel into the next test. All reported tests are started using fuel remaining from a previous identical test, where remaining fuel is usable in that stove. For some stoves this is not possible and the matter does not arise. Stoves in this category (not able to re-use the fuel remaining) include most TLUD char-making pyrolysers and some gasifiers, though the matter remains less than fully explored.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The fuel consumption (the measurement we are trying to provide to the programme manager) is determined by measuring the fuel mass consumed per replication of a task. It is similar in principle to a KPT in that one observes fuel disappearing, but instead of disappearing in to a homestead, it is measured disappearing into the stove each time it is used. It is a very non-negotiable measurement. Either the fuel is going into the stove or it is not. Credit is given for fuel remaining that can be used next time: <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Energy consumption in the form of raw fuel per cycle = A-F [Joules]<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The result can be expressed in Joules or in unit of mass. Programme managers want to hear the ‘savings’ of a stove in % terms. Thus it is possible to use the calculated energy-equivalent of the mass of fuel needed for each replication, and the reduction in that mass with a new candidate stove.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Thus results can be presented as “This stoves uses 3 kg of fuel and that one uses 2 kg to complete the assigned task.” Or it can be presented as the second stoves saves 1/3 of the fuel. It is <i>not</i> desirably to present this as an ‘efficiency’ unless the efficiency in question is carefully explained as an efficiency is always a ratio.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The major misunderstanding that has dogged the stove community for so many years, embedded as it was in the UCB-WBT, is the idea that the heat transfer efficiency is the same as the fuel efficiency. This is a hangover from the days of power station measurements and when the calculation was first adopted by the stove community, power station calculations were employed. They were quickly adapted to be more realistic (as power stations are not measured when starting and stopping). By 1984 the Eindhoven Group had a pretty good handle on this calculation and the term ‘percentage heat utilized’ was widely adopted. The problem with PHU was the defective understanding of the heat transferred during simmering so results are inconsistent, that is to say, highly variable, even if the stove itself was not. This was dealt with (by Eindhoven) by assuming fuel remaining was thrown away. That is, char remaining was not useful for the next fire. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Efficiencies: <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Here is a slide from a presentation on measuring stove performance:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA><img width=566 height=420 id="Picture_x0020_1" src="cid:image001.jpg@01CF3146.43700400"></span><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The calculation of the “heat transfer efficiency” has been used in place of the “overall thermal efficiency” in many calculations. Heat energy potentially available in fuel consumed minus the heat energy theoretically available in the char remaining is not the heat energy delivered by the fire. There are so many things that are <i>not</i> the ratio we want I can’t list them all. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Upon looking closely, you will see from the above slide that the heat theoretically released by the fire based on the missing mass of fuel is not really the heat available to the pot – it has to be factored for combustion efficiency and mechanical losses like dropped fuel and unusable fuel remaining. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>It is not the heat released by the fire either. That is why I call that number (as you have calculated it and as the UCB-WBT calculated it) a ‘proxy for the heat transfer efficiency’. It does not use the heat actually available from the fire nor does it use the heat transferred to the pot, nor does it even use the heat that changes the temperature of the pot and what is in it (sensible heat). It is an ‘efficiency’ because it is a ratio but it is not a useful number for rating stove performance, or even designing a stove. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Let’s call the energy that could have been released from the burned fuel ‘Fuel Energy”. Let’s call the energy in the char remaining, “Char Energy”. Let’s call the difference between them, ‘Fire Energy”.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Fuel energy – char energy = fire energy<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Agreed?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Fuel energy can be expressed as a mass of fuel.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Char energy can be expressed as a mass of fuel equivalent (which is how the GACC-WBT works)<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Fire energy can also be expressed as a mass of fuel equivalent.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Let’s call the heat getting into the pot, “Pot Energy”.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Let’s call the heat accumulated in the pot, “Net heat gained by the pot” which is the same as ‘sensible heat’ or ‘detectable heat’ as the term <i>sensible</i> implies.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>“Pot energy” and “Net heat gained by the pot” are not equal because some heat that gets into the pot is lost from the sides, especially by convection and the amount as a % of the total, varies (a lot) with firepower.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Back to Efficiency:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><u><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>“Net heat gained by the pot”<o:p></o:p></span></u></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>“Fuel energy – char energy”<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><div><div><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Is <i>not</i> the energy efficiency, nor is it the fuel efficiency, nor is it the heat transfer efficiency, not is it the mass equivalent ratio of any efficiency. It is just a number. It is used as <i>a proxy</i> for the heat transfer efficiency. It is not the heat transfer efficiency, but it is close enough for government work, apparently, because the UNFCCC uses a variation of it to determine ‘fuel savings’ which clearly cannot be the case if the stove produces a lot of char. I believe it is the same as your </span><b><i><span lang=EN-CA>Eff 3</span></i></b><b><span lang=EN-CA style='color:#1F497D'>.<o:p></o:p></span></b></p><p class=MsoNormal><b><span lang=EN-CA style='color:#1F497D'><o:p> </o:p></span></b></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>It is not the answer programme managers are asking for. They are asking what the reduction in fuel consumption is, which is easily determined by measuring the fuel demand of the stoves during each replication of the cooking task. It does not involve any jiggery-pokery with energy in some fuel fractions and not others.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Regarding the 85% efficient stoves:<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>A stove that has a very high combustion efficiency, burns all the fuel placed in it, and having a high heat transfer efficiency can put 85% of the energy theoretically available in the fuel consumed into the pot in the form of sensible heat. I have a water heater in my house that is 88% efficient calculated on this basis. I have a furnace that is 92% calculated on this basis. It is therefore possible to accomplish.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If the challenge is to provide a pellet burning, char-making stove with a rated fuel efficiency of 45% (also called the overall thermal efficiency), it would be a requirement to have a heat transfer efficiency that is above 45% in order to have char remaining as unburned fuel. If the heat transfer efficiency is 85% and the rated fuel efficiency is 45%, the difference of 40% can be delivered in the form of char remaining from the fuel consumed.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I don’t think you need to me put numbers on it to show this. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Of the original energy in the fuel consumed, 45% would get into the pot as sensible heat, and 40% would emerge as unburned char. To achieve this would require a fire heat (factored for combustion efficiency) to pot heat (net heat gained) efficiency of 85%. The system efficiency is 45% (because for each unit of fuel consumed, 45% of the energy available is doing something useful in the pot). The char production efficiency would be the mass of char yielded divided by the mass of char potentially yieldable (I suppose) or the mass of char divided by the dry mass of fuel used.<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The question most often posed by the programme managers is the relative fuel consumption of candidate stoves relative to the baseline products in common use. So far no one has asked for a char production ratio or a heat transfer efficiency or a heat transfer efficiency proxy. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Regards<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Crispin<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-CA style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p></div></div></div></body></html>