<html><head><style type="text/css"><!-- DIV {margin:0px;} --></style></head><body><div style="font-family:times new roman,new york,times,serif;font-size:12pt"><div><br>Charcoal will burn at a very slow rate and wood has to burn at a larger rate to maintain flaming combustion.<br>So for low and slow like for simmering, charcoal could be more efficient even considering all the energy wasted making the charcoal from wood.<br><br>Using wood for the high power phase of cooking like bringing a pot to boil and then using the charcoal made from the wood for low power cooking like for simmering or holding food hot just seems to fall into place.<br>I believe it was Crispin that said that a lot of efficiency is lost because the fuel wood is a size that required a too large a fire to maintain flaming combustion. A fire too large to be most efficient at capturing the heat with a pot.<br></div><div style="font-family:times new roman, new york, times,
serif;font-size:12pt"><br><div style="font-family:times new roman, new york, times, serif;font-size:12pt"><font face="Tahoma" size="2"><hr size="1"><b><span style="font-weight: bold;">From:</span></b> Crispin Pemberton-Pigott <crispinpigott@gmail.com><br><b><span style="font-weight: bold;">To:</span></b> Discussion of biomass cooking stoves <stoves@lists.bioenergylists.org><br><b><span style="font-weight: bold;">Sent:</span></b> Sat, April 20, 2013 4:34:23 PM<br><b><span style="font-weight: bold;">Subject:</span></b> Re: [Stoves] Last? Alternative to Charcoal<br></font><br>
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--></style><div class="WordSection1"><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">Dear Mike</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></p><div><div><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">></span>Great conversations on Charcoal verses everything else. I can't understand how percentages can be the same for all and less than charcoal? What no one seems to be speaking about is the inefficiency of making charcoal in the 1st place? <span style="color:#1F497D;"></span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></p><p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">To cut straight to the heart of the matter, the fact that charcoal ‘is inefficient’ is not a simple a statement as it first appears.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">Turning any biomass (it does not have to be a tree) into charcoal changes its properties a great deal. It first of all becomes dried completely which takes a great deal of energy and it why the energy of fresh char is about double (or more) the energy per kg of the biomass that was put into the process. The ‘total loss’ is not a simple as trying to match the potential fry fuel energy with some ‘loss’. That is an overly simplistic view so the get
somewhere with the conversation it is important to view entire system from the sources (a field or plantation of forest) to the heat inside the pot at the far end.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">Paul M mentioned that the transport for the equation he is putting together he set at 3 times that of wood fuel because of the area needed to produce the fuel. Well, that might be true in certain circumstances but it is not generally true and not for agrifuels turned into charcoal. The value of an agriwaste turned into char is greatly enhanced and as the transport is a variable, I prefer not to fix an expense for transport until the local circumstances.</span></p><p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">Paul, thanks for replying to my queries. I am holding open the issue of the transport value because as it is significant, I wouldn’t like to see a final outcome that was strongly affected by an assumption like triple the transportation cost. </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">Urban area produce a great deal of tree cuttings that is not exactly prized cooking fuel. The value of a processed fuel is high for a reason, not just production costs. Predictable fuels like char briquettes
(especially little ones that can be hopper fed) give much better performance than random tree cuttings.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">As it is true that a pelletized fuel (made from the same raw material as the char) has more total energy, it is fair to compare them in terms of their ‘as produced’ energy per unit mass, however the cost of making pellets is a heck of a lot higher per MJ than char. That matters in the overall energy equation.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",
"sans-serif";color:#1F497D;">Although people routinely suggest that pellets are a great fuel, the energy intensity is high. The Chinese machine that was mentioned recently on this list has 2 x 60 kW electric motors. Consider the GEK Power Pallet. It runs on wood pellets. There is a positive return on the system, meaning the Power Pallet can produce enough electricity to operate a machine that will make enough pellets to run the gasifier and the Power Pallet. However it might not also be able to produce the gasifier, the engine and the generator that produces the electricity and the wood pelleting machine with its components and motor. Do you see what I am getting at? Something has to power the system. We can’t take part of the system assuming that the energy needed to run it comes free from somewhere else.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",
"sans-serif";color:#1F497D;"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">Char making (from biomass in general) is a low tech energy non-intensive process that provides a net gain in energy, taking only biomass to begin with and produce net energy for cooking. At present the use of diesel trucks to move it has turned what used to be a biomass (draft animals) into an extended supply chain that probably, ultimately, runs on oil. That could be improved by using non-woody biomass as an input like the Sarai Stove fuel from sugar cane leaves, but only applies to certain areas where the distances are ‘right’. </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",
"sans-serif";color:#1F497D;">To look for real, bankable alternatives, we have to keep an open mind think of all the possible technologies that we could apply to the problems in the production and consumption chain. Innovative changes to the charcoal market, as were tried very successfully in Chad, can dramatically change the entire market into a sustainable, profitable and effective system for provision of non-fossil cooking fuels.</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;"> </span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">Regards</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri", "sans-serif";color:#1F497D;">Crispin</span></p><p class="MsoNormal"><span style="font-size:11.0pt;font-family:"Calibri",
"sans-serif";color:#1F497D;"> </span></p></div></div></div></div></div>
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