<html xmlns:v="urn:schemas-microsoft-com:vml" xmlns:o="urn:schemas-microsoft-com:office:office" xmlns:w="urn:schemas-microsoft-com:office:word" xmlns:m="http://schemas.microsoft.com/office/2004/12/omml" xmlns="http://www.w3.org/TR/REC-html40"><head><meta http-equiv=Content-Type content="text/html; charset=us-ascii"><meta name=Generator content="Microsoft Word 15 (filtered medium)"><style><!--
/* Font Definitions */
@font-face
{font-family:"Cambria Math";
panose-1:2 4 5 3 5 4 6 3 2 4;}
@font-face
{font-family:Calibri;
panose-1:2 15 5 2 2 2 4 3 2 4;}
/* Style Definitions */
p.MsoNormal, li.MsoNormal, div.MsoNormal
{margin:0mm;
margin-bottom:.0001pt;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
a:link, span.MsoHyperlink
{mso-style-priority:99;
color:blue;
text-decoration:underline;}
a:visited, span.MsoHyperlinkFollowed
{mso-style-priority:99;
color:purple;
text-decoration:underline;}
p
{mso-style-priority:99;
mso-margin-top-alt:auto;
margin-right:0mm;
mso-margin-bottom-alt:auto;
margin-left:0mm;
font-size:12.0pt;
font-family:"Times New Roman","serif";}
span.EmailStyle18
{mso-style-type:personal-reply;
font-family:"Calibri","sans-serif";
color:#1F497D;}
.MsoChpDefault
{mso-style-type:export-only;
font-family:"Calibri","sans-serif";
mso-fareast-language:EN-US;}
@page WordSection1
{size:612.0pt 792.0pt;
margin:72.0pt 72.0pt 72.0pt 72.0pt;}
div.WordSection1
{page:WordSection1;}
--></style><!--[if gte mso 9]><xml>
<o:shapedefaults v:ext="edit" spidmax="1026" />
</xml><![endif]--><!--[if gte mso 9]><xml>
<o:shapelayout v:ext="edit">
<o:idmap v:ext="edit" data="1" />
</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 Paul M<o:p></o:p></span></p><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","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'>Thanks for taking the time to consider this systematically, meaning as a systems problem. <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 will add one consideration that I did not see which is that the thermal efficiency (raw fuel to hot pot efficiency) of the stove is usually quite different between wood stoves and charcoal stoves.<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 have just been testing a charcoal stove (Anglo Supra and Anglo Supra Nova) which are widely used in this area for party cooking and commerce. They have an efficiency of about 50%. There is nothing like that available for wood. The Keren wood stoves, basically a sheltered fire made from terracotta, are about 18-22% efficient. Maybe 15%. <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 difference is large and when the numbers you correctly considered for the available energy in the forest delivered to the pot are factored for stove performance, the result is a surprise to many people, meaning a surprise for those who consider charcoal to be an ‘inefficient’ fuel overall. Not only is it not nearly as bad as they have assumed, it has easily be improved (all elements of the system).<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 jury is thus still out on which way to go with charcoal, even if it has a large crowd hissing at it. Charcoal is a major employer, it is a preferred fuel (mostly because it is clean burning and doesn’t make pots dirty) and the system is ripe for improvement.<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><p class=MsoNormal><span style='font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'>Dale, thank you for getting this discussion going. I think we all would agree that the traditional charcoal production & use systems around the world have much to be improved upon. <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'>Some comments - many in response to Chrispen's comments:<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'>1. I could not agree more about the social (& market) aspects of substituting dried woody biomass for charcoal. That is a big issue which has yet to be tackled. It could be a show stopper for some of the alternatives. <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'>2. In terms of transport economics, no doubt that charcoal has a substantially higher net (LHV) energy density than dry wood, not to mention wet wood. Consequently for the same amount of energy shipping the same distance charcoal wins hands down. <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'>For my analysis I used 10% moisture which assumes either aggressive solar drying or that some of the biomass is being burned to dry the remaining fuel. Even with this much drying, the hauling cost penalty of biomass over charcoal is about 67%. Where the analysis becomes interesting, at least to me, is when the whole system is considered. In this case we need to factor in the efficiency of the charcoal production vs. the woody biomass production and this effect on forest area required. Bottom line is that the charcoal must be hauled in from a much larger land area just because of the gross inefficiency of the charcoal making process. This has the potential to make the hauling cost on a per MJ basis actually 40% LESS for dried biomass. I say potential because it will all be specific to the forest area, it's density (tons of biomass / hectare) and it's distance from the point of fuel use. This collection hauling penalty for traditional charcoal, has not been discussed much from what I have seen. <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'>The other interesting point is that dried biomass is actually equivalent to charcoal on a MJ / m3 basis. Consequently, the truck will need to haul more weight per MJ with dried biomass, but not more volume. <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'>3. On the stove side, there is much work to do, from what I can tell, to make a TLUD burning dried biomass as attractive to the user as a charcoal stove burning charcoal. In fact it may never be. However, it seems to me that there is the potential. Given that this fuel is consumed in the city there should be an easy & efficient way to burn the residual charcoal. Also perhaps turn-down needs improvement in the gasification phase. And of course it needs to be simple to operate. Each one of these issues may represent substantial work to develop solutions for. <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'>4. Speaking of development, a low capital method for distributed drying of woody biomass is another area that will need substantial appropriate technological development for this to be successful. <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'>5. Final comment on Pellets: I am most familiar with pellets, and many know they are now a major energy commodity in the developed world. The downside is that they take much higher electrical or diesel energy input than simply chipping or splitting biomass. Also, they require more capital, and the plants are more complex to operate and maintain. Consequently they are less suited for a widely distributed system - like the existing charcoal production - especially in developing countries. If the pellet plants are large then the wet wood is hauled further to get to the plant and the benefit in comparison to charcoal is reduced. Still they are the most uniform, transportable, and appealing of the dried woody biomass options. It just remains to be seen which of these different approaches - pellets, chipped, crumbled, or split dry biomass will develop more over time. <o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'><o:p> </o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'>- Paul<o:p></o:p></span></p></div><div><p class=MsoNormal><span style='font-size:9.5pt;font-family:"Arial","sans-serif";color:#222222'><o:p> </o:p></span></p></div><div><p class=MsoNormal><o:p> </o:p></p></div><p class=MsoNormal>-- <o:p></o:p></p><div><p class=MsoNormal>Paul M. Means<o:p></o:p></p></div><p class=MsoNormal>Research & Testing Manager<o:p></o:p></p><div><p class=MsoNormal>Burn Design Lab <o:p></o:p></p></div><div><p class=MsoNormal><a href="tel:%28253%29%20569-2976" target="_blank">(253) 569-2976</a> (mobile)<o:p></o:p></p></div><div><p class=MsoNormal><a href="http://www.burndesignlab.org/" target="_blank">http://www.burndesignlab.org/</a><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:7.5pt;font-family:"Arial","sans-serif"'>“In the whole of world history there is always only one really significant hour – the present…If you want to find eternity, you must serve the times.”<i> - </i></span><span style='font-size:7.5pt;color:#330033'>Dietrich Bonhoeffer</span><o:p></o:p></p></div></div></body></html>