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</o:shapelayout></xml><![endif]--></head><body bgcolor=white lang=EN-CA link=blue vlink=purple><div class=WordSection1><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Dear Huck<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>The last question first:<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>How much ‘tree’ do you need to cook?<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>That is the question. If you are cooking on multiple stoves one that makes charcoal and one that burns it, you can analyse that as a ‘system’ but remember that to evaluate them you have to do them separately. A lot of conflict, actually, has emerged over this question because those who want to make charcoal-making stoves don’t want them penalised for being inefficient, even if they are. They bring a lot of arguments in favour of this or that aspect of a system of which the stove is a port. No problem – such arguments are reasonable when discussing systems, however your question is strictly about stove performance.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>The way you phrased the question is the same as the way the UNFCCC phrases it – how much tree for how much cooking. The assumption is that less trees used for the same amount of cooking is more efficient.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>When calculations are made, however, people frequently calculate the energy released, not the amount of fuel consumed and the two numbers are nearly always different. We are not burning gasoline. Cars do not make charcoal. ‘Leftovers’ can be a significant portion of the energy available, <o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>As Prof Lloyd just remarked a couple of days ago, it takes a lot of work to get fuel and people are not crazy – they want to burn it before going out to get more.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>It is for these reasons that het Clean Stove Initiative Indonesia (CSI-Indonesia) uses a calculation method that captures the amount of raw fuel needed to complete another test burn cycle. The energy in that ‘fuel consumed’ is determined. That is the energy available. The energy gained by the pot (including the heat gained by the pot material as it can be substantial) is determined over a cooking simulation. In the case of the CSI-Indonesia pilot the determination is made using the CSI-WHT (‘Water Heating Test’). This is an accurate measure of the energy gained by the pot – to within a few Joules.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Energy applied divided by energy drawn from the forest is the system efficiency, or ‘overall efficiency’.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Regards<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>Crispin<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'><o:p> </o:p></span></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Hi All,<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I found myself a little confused by the discussion. <o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Not being expert in the field, this is how I would pose my questions:<o:p></o:p></span></p><ol style='margin-top:0mm' start=1 type=1><li class=MsoNormal style='color:#1F497D;mso-list:l1 level1 lfo3'><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>There is a certain amount of energy per kilogram of wood (I’m going to stick with wood for the moment rather than all biomass).<o:p></o:p></span></li><li class=MsoNormal style='color:#1F497D;mso-list:l1 level1 lfo3'><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>When burned, some of that energy is realized and some is not, i.e. there is not complete combustion. How complete is the combustion? How much energy is released? That would be the first measure. I want this because it tells me about one component of the system and is useful for design. It does not tell me the net result for the user.<o:p></o:p></span></li><li class=MsoNormal style='color:#1F497D;mso-list:l1 level1 lfo3'><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>How much of the released energy goes into cooking? That would be my next measure. That should tell me what weight of wood people have to collect to cook their food. It is worth noting that the amount of energy that goes into cooking is also affected by the pots and lids used as well as how they fit onto the stove.<o:p></o:p></span></li><li class=MsoNormal style='color:#1F497D;mso-list:l1 level1 lfo3'><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>It is also important to know how much energy was expended to get the fuel and prepare it for use. Some of that energy is human energy so it gets treated a bit differently and has a different impact. For example, it doesn’t convert simply to climate impact (are humans low global warming gas emitters?). If you cut up the fuel a lot and process it a lot there is a cost there. I don’t know how that stacks up for gasifiers vs other stoves.<o:p></o:p></span></li><li class=MsoNormal style='color:#1F497D;mso-list:l1 level1 lfo3'><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Regarding charcoal. I am presuming you can still use the charcoal. I was, apparently erroneously, under the impression that gasifier stoves could continue to receive primary air and therefore burn the charcoal. I actually liked that idea because it was simple and used most of the energy in the stove. If you take the charcoal out of the stove you then have a couple of options for using it. You can burn it in another stove, which has some appeal as you can do a different kind of cooking with it (e.g. BBQ, or ?). But also seems like quite a bit of work and complication for a small amount of charcoal. Or, you can use it in the soil. So another question:<o:p></o:p></span></li><li class=MsoNormal style='color:#1F497D;mso-list:l1 level1 lfo3'><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Is a gasifier stove with charcoal (biochar) buried actually carbon negative?<o:p></o:p></span></li><li class=MsoNormal style='color:#1F497D;mso-list:l1 level1 lfo3'><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif"'>Then the other important measure: what are the emissions?<o:p></o:p></span></li></ol><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>And, a kind of crude question: with the ins and outs of this discussion is it the case that rocket stoves or some other stove is more efficient than the gasifiers? In my question by efficiency I mean kg of wood required for a Cameroonian to cook their meals?<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Which stove do they have to carry more wood for and do more fuel preparation for? (I’m not sure how you measure the combined work for those tasks).<o:p></o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span lang=EN-US style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Huck<o:p></o:p></span></p><p class=MsoNormal><a name="_MailEndCompose"></a><span lang=EN-US><o:p> </o:p></span></p></div></body></html>