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</o:shapelayout></xml><![endif]--></head><body 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 Jock<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><div><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D;mso-fareast-language:EN-US'>></span>The numbers I have for wood pellets suggest around 8,000 BTUs per pound. <span style='color:#1F497D'><o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>There is a pretty comprehensive list of heat values at the back of a WBT spreadsheet. 12,000 would be a a bit about right for charcoal. The heat value of char produced in a TLUD or a fire has not been very well studied. Jim Jetter’s Aug 2012 paper has some values.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The heat value of wood is only what people are going to get from it, not what it would be if it were dried (which also applies to charcoal).<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>I am in Central Java at the moment and the charcoal in the lab has been sitting around for a while. The average moisture content is 8.8% according the lab lady Julianna. The heat content is 26.7 MJ/kg which is slightly below the 12,000 BTU mark.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>The local wood even after months of drying is about 15-16% moisture. With a heat content of about 19.2 MJ/kg dry at 16% it is 15.7 MJ/kg. Lots of woods have a lower heat value than that and many people use damp wood – no doubt about it. It bubbles and dribbles continuously. So the reality is that what people put into their stoves is often below ½ the heat value of charcoal per kg. Further, the char produced by a TLUD is expected to be 0% moisture if it is used within a day or so it will pay to keep an eye on what exactly is being claimed. Fresh charcoal has a very low moisture level. Most fuelwood does not. That is the comparison I am thinking of. A direct comparison between the average fuelwood <i>as used</i> and locally made charcoal <i>as used</i> is ≈15.5 v.s. 29.5 MJ/kg.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If I put 1 kg of 15% moisture wattle (15.9 MJ/kg) into a TLUD stove and create 20% char (20% of the moist mass) the net heat provided by the fire is 10 MJ/kg. The heat available from the char is still 29.5 so the total is the difference the bit between: 15.9-10 = 5.9 MJ.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>If someone wants to switch from wood fuel to a ‘cleaner’ TLUD and that TLUD is not 1.5 times as efficient in transferring heat, their raw fuel consumption will increase.<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Regards<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'>Crispin<o:p></o:p></span></p><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p></div></div></body></html>