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<div class="moz-cite-prefix">Crispin,<br>
<br>
I was looking up the topic of Zambia (part of a task I have been
doing recently looking at what countries might be seeking out
biochar-producing stoves), and I came across this old email, where
right at the end (bottom) you write, "<span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">The
soils of Zambia are already <i><b>famously productive</b></i></span>".<br>
This was <u>not</u> the impression that I had been given about
Zambia:<br>
<br>
<a class="moz-txt-link-freetext" href="http://en.wikipedia.org/wiki/Ecoregions_of_Zambia#Soils">http://en.wikipedia.org/wiki/Ecoregions_of_Zambia#Soils</a><br>
<ul>
<li><span style="color: rgb(0, 0, 0); font-family: sans-serif;
font-size: 13px; font-style: normal; font-variant: normal;
font-weight: normal; letter-spacing: normal; line-height:
19.200000762939453px; orphans: auto; text-align: left;
text-indent: 0px; text-transform: none; white-space: normal;
widows: auto; word-spacing: 0px; -webkit-text-stroke-width:
0px; background-color: rgb(255, 255, 255); display: inline
!important; float: none;"><big>Red sandveld</big> soils <b>cover
<u>most of the country</u></b>, and are generally <big><b>not
very fertile</b></big> due to weathering and leaching;
the top soil is <big><b>sandy</b></big><span
class="Apple-converted-space"> </span></span></li>
</ul>
<br>
<ul style="line-height: 19.200000762939453px; list-style-type:
disc; margin: 0.3em 0px 0px 1.6em; padding: 0px;
list-style-image:
url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAANAQMAAABb8jbLAAAABlBMVEX///8AUow5QSOjAAAAAXRSTlMAQObYZgAAABNJREFUCB1jYEABBQw/wLCAgQEAGpIDyT0IVcsAAAAASUVORK5CYII=);
color: rgb(0, 0, 0); font-family: sans-serif; font-size: 13px;
font-style: normal; font-variant: normal; font-weight: normal;
letter-spacing: normal; orphans: auto; text-align: start;
text-indent: 0px; text-transform: none; white-space: normal;
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;
background-color: rgb(255, 255, 255);">
<li style="margin-bottom: 0.1em;"><big>Grey dambo</big> soils
contain more nutrients but are waterlogged in the rainy season
and often <big><b>very acidic</b></big>, restricting the
plants which can grow there to sedges and wiry grasses
tolerant of marshy conditions.</li>
</ul>
<ul>
<li><span style="color: rgb(0, 0, 0); font-family: sans-serif;
font-size: 13px; font-style: normal; font-variant: normal;
font-weight: normal; letter-spacing: normal; line-height:
19.200000762939453px; orphans: auto; text-align: left;
text-indent: 0px; text-transform: none; white-space: normal;
widows: auto; word-spacing: 0px; -webkit-text-stroke-width:
0px; background-color: rgb(255, 255, 255); display: inline
!important; float: none;"><big>Kalahari Sands</big> in the
south-west of the country are <big><b>infertile and do not
retain moisture</b></big></span></li>
</ul>
ONLY:<br>
<ul style="line-height: 19.200000762939453px; list-style-type:
disc; margin: 0.3em 0px 0px 1.6em; padding: 0px;
list-style-image:
url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAANAQMAAABb8jbLAAAABlBMVEX///8AUow5QSOjAAAAAXRSTlMAQObYZgAAABNJREFUCB1jYEABBQw/wLCAgQEAGpIDyT0IVcsAAAAASUVORK5CYII=);
color: rgb(0, 0, 0); font-family: sans-serif; font-size: 13px;
font-style: normal; font-variant: normal; font-weight: normal;
letter-spacing: normal; orphans: auto; text-align: start;
text-indent: 0px; text-transform: none; white-space: normal;
widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;
background-color: rgb(255, 255, 255);">
<li style="margin-bottom: 0.1em;"><big><b><big>Black soils</big>
of floodplains</b></big> are fertile, grasses grow on them
as soon as the annual flood recedes and provide a rich
resource for herbivores.<b> If the annual flood is <u>disrupted
by dams</u>, woody shrubs of lower nutritional value tend
to replace grasses and so reduce the number of herbivores
and biodiversity.</b></li>
</ul>
<br>
Are you referring (only) to the "Black soils of floodplains"?
What about the rest of the country?<br>
<br>
Regards,<br>
<br>
<pre class="moz-signature" cols="72"> Lloyd Helferty, Engineering Technologist
Principal, Biochar Consulting (Canada)
<a class="moz-txt-link-abbreviated" href="http://www.biochar-consulting.ca">www.biochar-consulting.ca</a>
48 Suncrest Blvd, Thornhill, ON, Canada
905-707-8754
CELL: 647-886-8754
Skype: lloyd.helferty
Steering Committee coordinator
Canadian Biochar Initiative (CBI)
CURRENTS, A working group of Science for Peace
<a class="moz-txt-link-freetext" href="http://www.scienceforpeace.ca/currents/">http://www.scienceforpeace.ca/currents/</a>
President, Co-founder & CBI Liaison, Biochar-Ontario
National Office, Canadian Carbon Farming Initiative (CCFI)
Organizing team member, 2013 N/A Biochar Symposium:
<a class="moz-txt-link-abbreviated" href="http://www.carbon-negative.us/symposium">www.carbon-negative.us/symposium</a>
Member of the Don Watershed Regeneration Council (DWRC)
Manager, Biochar Offsets Group:
<a class="moz-txt-link-freetext" href="http://www.linkedin.com/groups?home=&gid=2446475">http://www.linkedin.com/groups?home=&gid=2446475</a>
Advisory Committee Member, IBI
<a class="moz-txt-link-freetext" href="http://www.linkedin.com/groups?gid=1404717">http://www.linkedin.com/groups?gid=1404717</a>
<a class="moz-txt-link-freetext" href="http://www.facebook.com/group.php?gid=42237506675">http://www.facebook.com/group.php?gid=42237506675</a>
<a class="moz-txt-link-freetext" href="http://groups.google.com/group/biochar-ontario">http://groups.google.com/group/biochar-ontario</a>
<a class="moz-txt-link-freetext" href="http://www.meetup.com/biocharontario/">http://www.meetup.com/biocharontario/</a>
<a class="moz-txt-link-freetext" href="http://www.biocharontario.ca">http://www.biocharontario.ca</a>
<a class="moz-txt-link-abbreviated" href="http://www.biochar.ca">www.biochar.ca</a>
"Producing twice as much food with diminishing resources, without further loss of natural habitats and biodiversity and in a changing climate may be the greatest challenge facing humanity."
- Lloyd Helferty</pre>
On 2011-11-14 3:35 PM, Crispin Pemberton-Pigott wrote:<br>
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<p class="MsoNormal"><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Dear
Vetle<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
is exactly the sort of information that builds the case for
a new stove or a new approach to fuelling and operation.<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">Use
acceptance is a major issue and the follow-up is important –
meaning do the new stoves remain in use. When they do, it is
often for reasons that have to do with fuel availability in
my limited experience. Not have to go as far or spend as
much for fuel is a strong incentive. The only thing that
mitigates hard against it is if the stove is inconvenient to
use or won’t cook properly. African women tend to like a
high heat (high firepower) to ‘cook fast’ so speed to boil
is important.<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><span style="color:#1F497D">></span>The 6 liter Peko Pe
stove can be filled with 600 grams of Maize cobs, with <br>
the sizes of 40-60 mm, it will burn for about 30 minutes and
boil one <br>
liter of water within 9 minutes after ignition (6,5 minutes
after the pot <br>
is put on the "flame"). <span style="color:#1F497D"><o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Is
1 litre large enough to interest a family? How much to
people cook at a time? The answer might be ‘a little in the
morning and a lot in the evening’. It is quite reasonable
for there to be two stove sizes or for one to be used only
for certain tasks. If the fit is good, people will adopt
them.<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">If
I estimate 600 g @ 15% moisture (air dry in summer) I get
about 7.8 MJ of potential energy. Subtracting for 20% char
(125 g) I get 4.1 MJ of heat over that 30 minutes. That is
2.3 kW average (with perhaps a peak of 3 kW?). Does that
sound reasonable? Is the heat fairly constant during that
time? If so, it is going to have a pretty constant thermal
efficiency.<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">If
the fire is low for 2.5 minutes then the pot goes on, and
the boiling is 6.5 minutes per litre, that is an overall
efficiency of about (0.335 MJ heat absorbed / 0.975 MJ heat
applied) = 34%. If the power is not up to that 2.5 kW
average at the time, perhaps it is higher. If the fire is
really large at that time, perhaps the efficiency is In the
high 20’s. Does any of this sound like what you are seeing?<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">30%
is pretty good. <o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">So
the information I will be looking for relates to the cooking
power in the first phase (pyrolysis), the duration of the
burn and the heating power that is available if one wanted
to continue to simmer on the remaining char.<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">There
is a test which would be very valuable and it is a water
heating (not boiling) test.<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Put
on a large pot with a lot of water, large enough that it
will not boil for at least 40 minutes. Record the
temperature every 20 seconds or so (be regular to make it
easier to analyse) using a thermometer that gives 0.1
Degrees.<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">As
the thermal efficiency will probably not change a great deal
during the cooking session, the temperature rise <i>rate</i>
is an indicator of power output. It can be calculated for
various intervals based on time or temperature. I have
attached a typical result of such a test for an old Panda
paraffin stove using a heterogeneous test protocol. The top
blue line is the mass of water remaining. You can see when
the stove was changed from High to Medium power as the
boiling rate (water mass loss) changes. The thermal
efficiency line (green) detects a change in efficiency with
the turn-down.<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">If
the power level changes the slope of the water heating line
will change. This can tell you what the power change is as
the stove goes from ignition to a fully developed fire to a
late-pyrolysis burn. This information is very valuable for
you. It would be very helpful if you share the result. Using
this approach, you can tune the performance to a cooking
task in a given community.<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">If
the pot boils during this type of test the result is harder
to get because it has to be done on a scale but it can be
done if you have to. <o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">></span>For
normal cooking of Nshima and similar food <br>
preparing, 30 minutes would be enough for each meal
in everyday use. <span style="color:#1F497D"><o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">For
South Africa and vicinity it would take 45 minutes after
boiling to cook ‘pap’ which is much longer.<o:p></o:p></span></p>
<p><span style="color:#1F497D">></span>Cooking Nshima need
less than 10 minutes so usually they can prepare most of their
additional food with one filling. <span style="color:#1F497D"><o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">That
is a very good fit then, especially if adding some chopped
wood will extend it by a few minutes if needed. Do people
object to chipping/chopping the wood? Zimbabwe (rural) had
difficult with splitting wood for cooking because the trees
are so hard. That problem is avoided it no wood or little
wood is involved. As the maize cobs collect around the house
it should be used first I guess. Hopefully.<o:p></o:p></span></p>
<p><br>
<span style="color:#1F497D">></span>We do feel that 6 liter
Peko Pe stove is a suitable size for unprocessed <br>
BIOmass wich are most available around the farms. <span
style="color:#1F497D"><o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Agreed,
by the sound of it. You have a good match between the stove,
fuel and the cooking task.<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">></span>Since
they already are cooking with one pot at the time, we don’t
think <br>
they need to have more than one stove,. <span
style="color:#1F497D"><o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Good
point. How do they prepare the ‘relish’ to go with the
nshima? I have seen it prepared in a smaller separate pot.<o:p></o:p></span></p>
<p><span style="color:#1F497D">></span>This is off course an
investment cost up for discussion for every household. When
less cooking time are needed they can <br>
just use less fuel. <span style="color:#1F497D"><o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Exactly.<o:p></o:p></span></p>
<p><span style="color:#1F497D">></span>With beans, the
farmers will spend more time for cooking. This can either <br>
be done by empty the stove and refilling it with maize or use
smaller cobs <br>
(>10 - 20mm) to get more mass into the stove (800g = <40
min "flame time") or also by <br>
using other kind of denser BIOmass. Chopped wood will burn for
more than 1 <br>
hour. <span style="color:#1F497D"><o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Is
the burn rate (mass per minute) the same with all the fuels
or do see a noticeable difference?<o:p></o:p></span></p>
<p>So far it seems that the farmers are satisfied with both the
size and cooking time. Time will show if adjustment
of stove size are required. <span style="color:#1F497D"><o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Agreed.
<o:p></o:p></span></p>
<p><span style="color:#1F497D">></span>Since the farmers in
this project are targeted to collect BIOchar from maize cobs
used for household energy purpose, they will refill the stove
when needed to get sufficient cooking/energy time. <span
style="color:#1F497D"><o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">They
will probably do that until they run low on fuel and there
is nothing wrong with that.<o:p></o:p></span></p>
<p><span style="color:#1F497D">></span>The BIOchar will be
stored for later to be used as soil improvement instead of
using it as glowing charcoal. <span style="color:#1F497D"><o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I
understand that process. <b>The soils of Zambia are already
famously productive</b> so any effect will be important to
document.<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">I
really appreciate you taking the time to provide hard data
for us who are disconnected from the work on the ground. I
would have shown one to the Chinese rural energy delegation
Roger Samson is bring around this week if I had a working
sample. We are going to demonstrate several stoves that can
burn pelletized (and chunked) switchgrass to try to generate
interest in TLUD technologies.<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Thanks<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D">Crispin<o:p></o:p></span></p>
<p><span
style="font-size:11.0pt;font-family:"Calibri","sans-serif";color:#1F497D"><o:p></o:p></span><br>
</p>
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