<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class=""><div class="">Hi all:</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>1. I have just wasted too many hours on this, so have decided to not respond to all of this new message. Nothing added below my sign-off - because of wanting to use less time on this.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>To forewarn: I find no merit in any of Crispin’s approach, 4-pager, or the dialog. (Actually a bit worse in Frank Shield’s comments). Paul Anderson was correct in all he said - but I’ll wager he found the material below even more mysterious - we now have to contend with a third type of efficiency - on top of having to believe his second test helps define the first. Six numbers are needed to replace a simple statement of the energy content of the saved char?</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>2. My first problem was not being able to even read the pdf. Eventually I found an Apple/Mcc “quick read” command so I could read it once (only - and couldn’t save it). Possibly Crispin put sort of non-edit command in. I finally got a copy I could save but still couldn’t copy or edit - by downloading at the “stoves” site (and messages there saying it had been scrubbed - maybe that site is at fault). An hour lost in just being able to read this pdf.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>3. Besides Paul’s two typo-catches, in the next to the last line of section 2.5, replace “<i class="">0.15 MJ was lost”</i> with “<i class="">1.5 MJ was lost.” </i>This 1.5 MJ was due to a non-happening (fines) in real TLUDs - and (curiously) makes the TLUD looks bad - when just reducing this error would clearly make the TLUD look the best.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>4. A different reason for objecting to the computations is that way too much charcoal was thrown way (1.5 MJ worth) as valueless (and any fines would have great value as biochar anyway - and so should be considered). Since we start with 10 MJ (weight not given), this is about 10/18 = 550 gm of wood. Giving zero credit to 1.5 MJ at 30 MJ/kg gives only 50 gm of char - which (multiplying by 4 [assuming a char production efficiency by weight of 25%]) started as 200 gm of wood (200/550=36%??). This doesn’t make sense - in part because these are all made-up, not real numbers. </div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>5. Below has this response to Paul (and one needs to read a lot more to have this short exchange make sense - and I predict it won’t)</div><div class=""><br class=""></div><div class=""><blockquote type="cite" class=""><div bgcolor="#FFFFFF" text="#000000" lang="en-GB" class="" style="background-color: rgb(255, 255, 255); line-height: initial;"><div id="_originalContent" class=""><i class="">>And that is where Ron and I and others have been disagreeing with you. </i></div><div id="_originalContent" class=""><i class=""><br class=""></i></div><div id="_originalContent" class=""><i class="">So this is your chance to show how the energy in the fuel consumed should be counted.</i></div></div></blockquote></div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>My own “show how” answer is to just do what Jim Jetter already does (and most others??): just report the energy content in Stove 1’s produced char. Crispin has to measure this any way to do all his other computations - that have nothing to do with Stove 1 performance. I think Paul may be saying the same.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>6. I note that there is no use of the word inefficiencies anywhere is this thread. That is what we should be concentrating on. For me it is 100% minus the first stove efficiency (25%) and the char-making efficiency (50%) = 25%. I believe Jim Jetter has said the same. Anyone saying they believe they can build the first number (25%) by diminishing the second (50%) needs to cite real data. TLUDs show low inefficiencies as described here. The reasons are unclear.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>7. Crispin says we shouldn’t consider the energy content of the char as valuable if it is headed for biochar. I don’t buy that. That char energy still has a potential. His is like saying the potential energy due to height difference in a hydro system isn’t real energy. The first law of thermodynamics says that energy is conserved. Potential energy is real energy.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>8. He also says (below) that placing char in the ground removes forests faster. Note that most char is today produced with 15% or so efficiency - in the boondocks. Not only is there no productive use of the pyrolysis gases - but they are even more global warming than CO2. TLUD stoves will save even when they produce char with the above 25% supposed energy efficiency (and most TLUDs do much better than that low-ball figure). Moreover, the Amazon’s terra preta char (after 500+) years is still several times more soil-productive. We pushing biochar are doing so to grow forests - not remove them faster - as most rural present charcoal production is doing. And we don’t need to cut down forests for stoves - ag residues, small twigs, fallen branches, dead trees, etc are much preferred over the trees normally cut down (typically when growing fastest) to make most third world char.</div><div class=""><br class=""></div><div class=""><span class="Apple-tab-span" style="white-space:pre"> </span>9. In sum, Crispin’s example, after correcting or including his non-real-world handling of the value of charcoal fines, is a wonderful case for char-making stoves.</div><div class=""><br class=""></div><div class="">Ron</div><div class=""><br class=""></div><br class=""><div><blockquote type="cite" class=""><div class="">On Nov 28, 2015, at 12:34 PM, Crispin Pemberton-Pigott <<a href="mailto:crispinpigott@outlook.com" class="">crispinpigott@outlook.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><div bgcolor="#FFFFFF" text="#000000" lang="en-GB" style="background-color: rgb(255, 255, 255); line-height: initial;" class=""> <div style="width: 100%; font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);" class="">Dear Paul </div><div style="width: 100%; font-size: initial; font-family: Calibri, 'Slate Pro', sans-serif, sans-serif; color: rgb(31, 73, 125); text-align: initial; background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">>Typographical errors: </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">Noted. Thanks. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">
<br class="">>Content:<br class="">>Good exercise. Well done. Helpful for further discussion. Yes,
there can be cooking systems with 2 stoves such as you describe.<br class="">
<br class="">>But there is one issue concerning first paragraph of Item 2.5 (page
2): <br class="">
<br class="">>The first 2 lines are fine. But it seems that the final two lines
are trying to say that fuel efficiency is the same as energy
efficiency. I read this at least 6 times. How about some
re-wording to clarify what you are saying. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">I was attempting to describe the efficiency with which the energy supplied to the stove is delivered to the pot up to the time the flame goes out. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class="">>You and I have agreed in the past that fuel efficiency and energy
efficiency are not the same. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">I cannot think of a better term at the moment. Yes it is a change in my choice of words. While I could have chosen 'cooking efficiency' the heat might not be applied to cooking, it could be something else. I am open to suggestions. One might consider the space heating efficiency. The main point of the exercise it to show that one cannot count some portion of the energy twice. Nothing can be more than 100% efficient without invoking magic. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">>For Stove1 the fuel efficiency is
based on wood fuel. Then for Stove2 you switch to have the fuel
efficiency based on charcoal.</div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">That is correct. My major point has been communicated it appears. The fact that the appearance of the fuel changed does not change the energy content. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">>But you are not giving any credit to
Stove1 for having produced the fuel for Stove2. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">A very important comment! Stove1 did not "produce fuel". That is a misconception. The fuel was produced by the forest. Stove1 extracted some of the energy available from the fuel and changed its appearance. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">While doing so it did some cooking. At flame-out the remaining matter, charcoal, was no longer useful to Stove1. It only extracted 1/2 the energy available to it and only 1/4 of the fuel's energy was delivered to the pot. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">No "fuel" was "produced". It was was always "fuel" and some of the energy was extracted - leaving half un-released. There is nothing to "credit". If Stove1 was the only product you had, 1/2 the energy was left at the end in an unusable form (for that stove) so the next meal requires more fuel from the forest. It is that requirement that is consuming the forest, often unsustainably. Buying a second stove to burn the charcoal does not increase the performance rating of Stove1. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">>And that is where
Ron and I and others have been disagreeing with you. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">So this is your chance to show how the energy in the fuel consumed should be counted. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">It is important that you demonstrate how the two are assessed together, as I did, and then to analyse them separately using the same approach. Follow the energy. If the cooking efficiency is correctly assessed, then the combination of two stoves will be correct as well. <br class="">
<br class="">If a different, single stove that has the fuel input of Stove1 and the remnant ash content of Stove2, and further, delivers the same cooking energy into a pot as the combined performance of Stoves 1+2, then the performance rating of that single stove will be exactly the same rating as the two stove combination, as it should be, because it did the same amount of work with the same quantity of fuel. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">A chain of three stoves can be imagined. No correct method of analysis can have as a result an efficiency that is greater than all the work done divided by all the energy available. The term 'energy efficiency' can correctly be applied to any part of that system, or the sum of all parts. It's a pretty good name. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">I hope a clear distinction between the energy efficiency (or cooking efficiency) and the thermal efficiency has been demonstrated. The thermal efficiency does not take cognisance of the total energy available in the fuel consumed, just the energy in the missing fuel. Thus it can't be used as a proxy for fuel consumption as has been done for years by the WBT. Notably, the Indian, Chinese and SeTAR test methods do not make that mistake. There was a pre-WBT 1 test method from 'Feu de Bois' and another from the University of Eindhoven that reported the fuel consumption correctly. <!--end of _originalContent --></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">While it would be nice to validate the WBT results as 'fuel consumption', it instead reports the thermal efficiency which is a different metric. That difference is the main reason why WBT lab tests do not match field observations of fuel use. A second reason for the mismatch in results is the differences in testing context but we can leave that for another discussion. </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class=""><br class=""></div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">Regards </div><div id="_originalContent" style="background-color: rgb(255, 255, 255);" class="">Crispin </div><style class=""><!--
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