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Philip<br>
<br>
I suspect something is not correct,<br>
<br>
1. In your example, the 0.395 kg wood contains 5930 kJ of total
energy.<br>
2. You calculate that the char produced would contain3163 kJ.
That would be 53.3% of the total energy is maintained in the char. <br>
3. Later you write that "the efficiency of char production would
have been ... 36.4%. <br>
<br>
I leave it for you and others check this out.<br>
<br>
3. At the end you say
<blockquote type="cite"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">this
would have been statistically indistinguishable from the
efficiency with no char production – i.e. it would have shown no
benefit to char production. </span></blockquote>
That statement could also be written "it would have shown no benefit
to cooking the regular, full-combustion way, without char
production." <br>
And since produced char can be stored for later use, is essentially
smokeless cooking for ventilated "indoor" cooking, and can be used
for other purposes, cooking with char-producing stoves could be
viewed as having some benefits.<br>
<br>
I respect those of you who are good number crunchers and know the
formulae. Please comment on the above. I am here to learn.<br>
<br>
Paul<br>
<br>
<br>
<pre class="moz-signature" cols="72">Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
Email: <a class="moz-txt-link-abbreviated" href="mailto:psanders@ilstu.edu">psanders@ilstu.edu</a>
Skype: paultlud Phone: +1-309-452-7072
Website: <a class="moz-txt-link-abbreviated" href="http://www.drtlud.com">www.drtlud.com</a></pre>
<div class="moz-cite-prefix">On 9/25/2017 4:29 AM, Philip Lloyd
wrote:<br>
</div>
<blockquote type="cite"
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<div class="WordSection1">
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I
carried out a thought experiment.<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">In
case 1, a cookstove burning wood boiled 5 litres of water at
an energy efficiency of 30%. The useful energy provided was
5*4.186*(100-15) = 1779kJ. This required
5*4.186*(100-15)/0.3 = 5930kJ. If the as-fired wood had a
LHV of 15MJ/kg, it would have needed 5930/15000 = 0.395kg
wood<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">In
case 2, the same stove was operated to produce charcoal
while also boiling 5litres of water. More wood would be
needed, because not all the wood would be combusted – some
would be left as char. If you fed 0.395kg wood to be turned
into char at 29% efficiency, and the char had an LHV of
28MJ/kg, then the char would have an energy of
0.395*28000*0.29=3163kJ. The wood from which it was prepared
had an energy content of 5930kJ, which was what was needed
to boil the water in the absence of char production. So
5930-3163 = 2768kJ of additional energy* would be needed to
boil the water if there was char production. At 15MJ/kg,
this is 2768/15000 = 0.185kg extra wood, or an increase of
47% in the wood supply. The total energy supplied would then
be 5930+2768 = 8698kJ. The energy efficiency of cooking
would therefore fall to 1779/8698*100 = 20.5%, while the
efficiency of char production would have been 3163/8698*100
= 36.4%. The system efficiency would have been 20.5+36.4 =
56.9%<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
you used the WBT formula, the efficiency of boiling with
char production would have been 1779/(8968-3163)*100 =
32.1%. Given the measurement errors inherent in the WBT
method, this would have been statistically indistinguishable
from the efficiency with no char production – i.e. it would
have shown no benefit to char production. <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">Prof
Philip Lloyd<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Energy
Institute, CPUT<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">PO
Box 1906<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Bellville
7535<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Tel
021 959 4323<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Cell
083 441 5247<o:p></o:p></span></p>
<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">PA
Nadia 021 959 4330<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">*This
assumes that there is no endotherm in the pyrolysis of wood
in the presence of air, and that all the pyrolysis products
except the char burn to provide heat. There is evidence in
the literature of no endotherm in the presence of air.<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 style="border:none;border-top:solid #B5C4DF
1.0pt;padding:3.0pt 0cm 0cm 0cm">
<p class="MsoNormal"><b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"
lang="EN-US">From:</span></b><span
style="font-size:10.0pt;font-family:"Tahoma","sans-serif";color:windowtext"
lang="EN-US"> Stoves
[<a class="moz-txt-link-freetext" href="mailto:stoves-bounces@lists.bioenergylists.org">mailto:stoves-bounces@lists.bioenergylists.org</a>] <b>On
Behalf Of </b>Paul Anderson<br>
<b>Sent:</b> Sunday, September 24, 2017 11:27 PM<br>
<b>To:</b> Discussion of biomass cooking stoves<br>
<b>Cc:</b> <a class="moz-txt-link-abbreviated" href="mailto:ndesai@alum.mit.edu">ndesai@alum.mit.edu</a>; Andrew Heggie; Crispin
Pemberton-Pigott<br>
<b>Subject:</b> Re: [Stoves] stoves and credits again<o:p></o:p></span></p>
</div>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Philip, Tom and all,<br>
<br>
Philip is mostly correct. Actually wood takes up (has) too
much WEIGHT. Wood has 3 times (or more, if the char is poorly
made) the ENERGY value of charcoal that could come from that
char. But it has about 5 times the DRY weight of the char,
plus there can be 20 to 50% moisture content to make the wood
even heavier. <br>
<br>
And the charcoal has almost double (30 vs. 16) the energy
content by weight, but char is so much lighter per unit of
volume. So the trucks are buldging upward and sideways with
the sacks of charcoal strapped to them. Weight of charcoal is
not a problem for most transport.<br>
<br>
Apart from the transportation issue, I believe that the appeal
of charcoal is that it does not smoke (not much). CO is
invisible and deadly, but the people learn to cook on the
balcony or keep some air flowing. And it does not turn the
bottom of the pots black.<br>
<br>
Charcoal is an attractive fuel. Too bad it is made by
processes that throw away 2/3rds of the energy. (So, let's
promote TLUD stroves and collect the char for sale to the
urban folks. Only one third of the cutting of wood/forest.) <br>
<br>
So, if 100,000 households (mainly in rural or peri-urban
areas) would use TLUDs, the resultant char would equal to the
energy needed for an approximately equal number of households
(mainly urban) that would want to burn charcoal. <br>
<br>
Now that would be FUEL efficiency measured by communities, not
by single stoves.<br>
<br>
Paul<br>
<br>
<br>
<o:p></o:p></p>
<pre>Doc / Dr TLUD / Prof. Paul S. Anderson, PhD<o:p></o:p></pre>
<pre>Email: <a href="mailto:psanders@ilstu.edu" moz-do-not-send="true">psanders@ilstu.edu</a><o:p></o:p></pre>
<pre>Skype: paultlud Phone: +1-309-452-7072<o:p></o:p></pre>
<pre>Website: <a href="http://www.drtlud.com" moz-do-not-send="true">www.drtlud.com</a><o:p></o:p></pre>
<div>
<p class="MsoNormal">On 9/24/2017 11:40 AM, Tom Miles wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal">That's probably why charcoal use is
increasing 5% per year in SSA compared with wood fuel at
1% per year. <br>
<br>
T R Miles Technical Consultants Inc. <o:p></o:p></p>
<div>
<div>
<p class="MsoNormal"><span class="apple-style-span"><a
href="mailto:tmiles@trmiles.com"
moz-do-not-send="true">tmiles@trmiles.com</a></span><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><span class="apple-style-span">Sent
from mobile. </span><o:p></o:p></p>
</div>
</div>
</div>
<div>
<p class="MsoNormal" style="margin-bottom:12.0pt"><br>
On Sep 24, 2017, at 8:50 AM, "<a
href="mailto:plloyd@mweb.co.za" moz-do-not-send="true">plloyd@mweb.co.za</a>"
<<a href="mailto:plloyd@mweb.co.za"
moz-do-not-send="true">plloyd@mweb.co.za</a>> wrote:<o:p></o:p></p>
</div>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<p class="MsoNormal">Just a thought on Sub Saharan
charcoal use. As Africa urbanizes, so it needs energy to
cook. Wood takes up too much volume, and the roads are
primitive. So it makes sense to use charcoal. A bicycle
load will keep ten homes cooking for a week. <br>
The use of char oal has everything to do with logistics
and nothing to do with the environment.<br>
Philip<br>
<br>
<br>
<br>
Sent from my Huawei Mobile <o:p></o:p></p>
<div>
<p class="MsoNormal"><br>
<br>
-------- Original Message --------<br>
Subject: Re: [Stoves] stoves and credits again<br>
From: Nikhil Desai <br>
To: Ron Larson <br>
CC: Andrew Heggie ,Crispin Pemberton-Pigott
,Discussion of biomass cooking stoves <br>
<br>
<br>
<o:p></o:p></p>
<div>
<p class="MsoNormal">Ron: <br>
<br>
What makes you believe that users of biomass-fuelled
stoves are predominantly growers (of biomass)? <br>
<br>
Saw the figures for urban charcoal markets in
Sub-Saharan Africa lately? Or looked at
non-household cooking (in my view roughly 50% of
cooking energy consumption worldwide)? <br>
<br>
Nikhil<o:p></o:p></p>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
<div>
<p class="MsoNormal">On Thu, Sep 21, 2017 at 10:54
PM, Ronal W. Larson <<a
href="mailto:rongretlarson@comcast.net"
target="_blank" moz-do-not-send="true">rongretlarson@comcast.net</a>>
wrote:<o:p></o:p></p>
<div>
<div>
<p class="MsoNormal">Andrew and list:<o:p></o:p></p>
</div>
<div>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<div>
<div>
<blockquote
style="margin-top:5.0pt;margin-bottom:5.0pt">
<p class="MsoNormal"> <o:p></o:p></p>
</blockquote>
<p class="MsoNormal"><br>
There appears to be a win win
situation here and I gather there is<br>
still a vast part of equatorial Africa
where annual burning takes<br>
place. However it brings me to another
reason I like the idea, though<br>
not the practicalities, of a
householder-subsistance farmer being
paid<br>
a subsidy funded by the developed
world. The trouble is I have a<br>
parochial view and not a good
worldview of what types of persons<br>
depend on biomass fuelled stoves. Are
they also predominantly growers?<o:p></o:p></p>
</div>
</div>
</blockquote>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><b>[RWL9: Yes to
Andrew’s last question. I disagree with
Andrew calling himself “parochial” -
when he supports (as do I) the ethics
of <i>“a subsidy funded by the developed
world”.</i></b><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><b> </b><o:p></o:p></p>
</div>
<p class="MsoNormal"><b>[RWL10: Agree
totally. And I think this is what will
eventually kill the geoengineering
technology that is often placed ahead of
biochar - BECCS. In BECCS, as with “clean
coal”, the CO2 from combustion (never
pyrolysis) is placed, as liquid, deep
underground. Major expenses needed to
protect the world’s soil are not needed
for biochar. Soil quality is closely
linked to carbon content - and biochar
does this with no penalty - while
apparently being the cleanest and most
efficient of all possible solid-fuel
stoves.</b><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><b>`Andrew - thanks for
your above rebuttal to Crispin.</b><o:p></o:p></p>
</div>
<div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
<div>
<p class="MsoNormal"><b>Ron<br>
<br>
</b><o:p></o:p></p>
<div>
<div>
<p class="MsoNormal"> <o:p></o:p></p>
</div>
</div>
</div>
</div>
<p class="MsoNormal" style="margin-bottom:12.0pt"><o:p> </o:p></p>
</div>
<p class="MsoNormal"><o:p> </o:p></p>
</div>
</div>
</div>
</div>
</blockquote>
<blockquote style="margin-top:5.0pt;margin-bottom:5.0pt">
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