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<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Dear Nganga<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I have changed the subject line to remove the chaff.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">The carbon footprint is of two types: the mass of carbon emitted and the mass of carbon dioxide – you have to know which you want. Unfortunately in the effort to demonize carbon dioxide, “carbon”
has been substituted in nearly all cases, because carbon is usually black and is easily considered “dirty” by the populace. Carbon dioxide has gained a reputation as “dirty” and “pollution” through repetition, not fact. This is unfortunate because it makes
it harder to answer your straightforward question. Confusion persists because it is not clear from “carbon” if it is C or CO<sub>2</sub>.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Let’s assume you want to know the CO2 output from a gasifier that consumes 50 kg per month. You ask for an annual number so I will express the consumption on an annual basis. 50 x 12 = 600 kg/annum.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">If you burned the wood completely, the answer is easy:
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Wood is ~50% carbon. More likely 45%-48% but 50% is often used because wood can range up to 52%.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">600 kg x 50% = 300 kg carbon.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">300 kg carbon emitted as CO<sub>2</sub> is (300 / 12 * 44) = 1100 kg CO<sub>2</sub> / annum.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">The “12” is the mole mass of carbon and the “44” is the mole mass of carbon dioxide.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">This would be the case if there was no moisture in the fuel.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">I caution that some people want to know the mass of carbon and others the mass of CO<sub>2</sub>.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Suppose it was wood pellets with a 6% moisture content (on a wet weight bases ‘WWB’) . Suppose the fuel is 94% wood and 6% moisture, by weight.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Then the CO<sub>2</sub> emitted would be proportionally less: 1100 kg x 0.94 = 1034 kg / annum.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">However, you said it was a gasifier. What is the carbon remaining after the burn is complete? Often there is a deliberate attempt to create char with a gasifier. Yes?
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">The carbon mass remaining should be subtracted from the total of 300 kg carbon without moisture and 300 x 0.94 = 282 kg carbon
<b>with</b> moisture. If the char yield is 20% and the char is 85% carbon, you get the following:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">600 kg biomass, 6% moisture<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">300 kg carbon minus 6% moisture = 282 kg carbon in the fuel fed.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">20% char yield = 282 x 0.20 = 56.4 kg char
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">(It is normal to express the char yield in terms of the dry mass input)<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">At 85% carbon in the char: 56.4 kg char 4 x 0.85 carbon = 47.94 kg carbon in the residue.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">That carbon not burned: (47.94 / 12 * 44) = 175.78 kg CO<sub>2
</sub>not emitted<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">So the emitted mass is (1034 kg CO<sub>2</sub> potential – 175.78 kg avoided) = 858.22 kg CO<sub>2</sub> emitted.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">All you have to do is substitute the relevant numbers into the formulas.
<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Best regards<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US">Crispin<o:p></o:p></span></p>
<p class="MsoNormal"><span style="mso-fareast-language:EN-US"><o:p> </o:p></span></p>
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<p class="MsoNormal"><b><span lang="EN-US">From:</span></b><span lang="EN-US"> Stoves <stoves-bounces@lists.bioenergylists.org>
<b>On Behalf Of </b>nganga liambai<br>
<b>Sent:</b> Monday, November 21, 2022 12:16<br>
<b>To:</b> Discussion of biomass cooking stoves <stoves@lists.bioenergylists.org><br>
<b>Subject:</b> Re: [Stoves] ***SPAM*** RE: ***SPAM*** Re: Stoves Digest, Vol 147, Issue 5<o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Helvetica Neue",serif">Greetings to all,<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Helvetica Neue",serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Helvetica Neue",serif">I am asking for assistance in respect of methodology for determining annual carbon footprint (in weight quantity) for a micro-gasfier stove consuming 50kgs of pellet fuel
per month. <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Helvetica Neue",serif"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Helvetica Neue",serif">Nganga Lyambai <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Helvetica Neue",serif"><o:p> </o:p></span></p>
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