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<DIV><FONT face=Arial>Dear Ron</FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><FONT face=Arial>Please see my comments inserted below, starting with #
</FONT></DIV>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV style="FONT: 10pt arial">----- Original Message ----- </DIV>
<DIV
style="FONT: 10pt arial; BACKGROUND: #e4e4e4; font-color: black"><B>From:</B>
<A title=rongretlarson@comcast.net
href="mailto:rongretlarson@comcast.net">rongretlarson@comcast.net</A> </DIV>
<DIV style="FONT: 10pt arial"><B>To:</B> <A title=Jetter.Jim@epa.gov
href="mailto:Jetter.Jim@epa.gov">James Jetter</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Cc:</B> <A
title=stoves@lists.bioenergylists.org
href="mailto:stoves@lists.bioenergylists.org">Discussion of biomass cooking
stoves</A> </DIV>
<DIV style="FONT: 10pt arial"><B>Sent:</B> Tuesday, April 23, 2013 9:27
PM</DIV>
<DIV style="FONT: 10pt arial"><B>Subject:</B> Re: [Stoves] FW: REQUEST for
complete sets of raw data ofcookstove tests.</DIV>
<DIV><BR></DIV>
<DIV style="FONT-FAMILY: Arial; COLOR: #000000; FONT-SIZE: 12pt">Jim:
(cc "Stoves")<BR><BR> Thanks. A few comments inserted
below<BR><BR></DIV>
<DIV style="FONT-FAMILY: Arial; COLOR: #000000; FONT-SIZE: 12pt">
<HR id=zwchr>
</DIV>
<DIV style="FONT-FAMILY: Arial; COLOR: #000000; FONT-SIZE: 12pt"><B>From:
</B>"James Jetter" <<A
href="mailto:Jetter.Jim@epa.gov">Jetter.Jim@epa.gov</A>><BR><B>To: </B><A
href="mailto:rongretlarson@comcast.net">rongretlarson@comcast.net</A>,
"Discussion of biomass cooking stoves" <<A
href="mailto:stoves@lists.bioenergylists.org">stoves@lists.bioenergylists.org</A>><BR><B>Sent:
</B>Tuesday, April 23, 2013 12:37:53 PM<BR><B>Subject: </B>RE: [Stoves] FW:
REQUEST for complete sets of raw data of
cookstove tests.<BR><BR>Ron,<BR><BR>It
was great talking with you in Phnom Penh.<BR>
<B>[RWL1: Agreed. I think you and GACC are to be much commended
for that Conference coming off well. If anyone from GACC can tell us if
Ppts (especially yours) will be available, that would be
helpful.</B><BR><BR>Let’s discuss a hypothetical example. We start with
a batch of biomass fuel that contains 10 MJ of (potentially available) energy.
After burning the batch of fuel in a certain stove, 2 MJ remains in
unburned char, 3 MJ went into the cooking process (pot), and 5 MJ was
“lost.”<BR><BR>Thermal efficiency is calculated per the WBT protocol as: 3 /
(10 – 2) = 0.375<BR> <B>[RWL2: For later use,
lets call this E1. See also a later note about possibly needing to
subtract energy in unconverted wood.]</B></DIV><STRONG></STRONG></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV><STRONG><FONT face=Arial># I would disagree with this approach, in that
the 2 MJ of char energy is just as lost to the stove test, as is the 5 MJ
loss.</FONT></STRONG><BR><BR>If the char is “discarded,” then thermal
efficiency can be calculated as: 3 / 10 = 0.3 <B>[RWL3
E2]</B></DIV><STRONG></STRONG></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"><STRONG><FONT
face=Arial># Whether the char is discarded or not is a situation outside of
what happens within the stove system. The "Stove Test" should should report on
stove performance, and should not be encumbered by factors outside the stove
being tested. </FONT> </STRONG><FONT face=Arial></FONT>
<DIV><BR>The thermal efficiency for char production can be calculated as: 2 /
10 = 0.2 <B>[RWL4:
E3]</B></DIV><STRONG></STRONG></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"><STRONG><FONT
face=Arial># I would suggest that</FONT> <FONT face=Arial>this term is rather
meaningless. If you could tell us how much energy was required to actually
make char containing the 2 MJ of energy, and the theoretically required energy
to make char, then one would have a valid term for "Thermal
Efficiency for Char Production. The 2 MJ is simply the energy content of
the char, and in no way reflects the energy required to make it. As
defined above it is really "% of input energy unavailable for use because of
char production".</FONT></STRONG>
<DIV><BR><BR>I think you are proposing to add the thermal efficiencies for
cooking and char production: ( 3 / 10 ) + ( 2 / 10 ) =
0.5<BR> <B>[RWL5: Right - E4=
E2+E3]</B></DIV><STRONG></STRONG></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"><STRONG><FONT
face=Arial>#</FONT> <FONT face=Arial>As just noted, "Thermal Efficiency
of Char Production" is a flawed concept.</FONT></STRONG>
<DIV><BR><BR>I’m not in favor of doing this, because, while there is a common
denominator, I think the numerators are like apples and oranges – cooking
(useful) energy and fuel (stored) energy.<BR>
<B>[RWL6: I agree they are apples and oranges. But sometimes
the question is asked - how much "fruit" do you have and in
this example the answer is certainly E4 = 0.5. As long as the
number "E3=0.2" is given a little prominence, I don't care if the number
E4 = 0.5 is also given. I expect promotional char-makers will be using
both E3 and E4, of course.</B></DIV><STRONG></STRONG></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"><STRONG><FONT
face=Arial># The "energy loss to char" can be given prominence in the test
report. This will tell customers who do not want char how little it makes, and
it will allow Promotional Char Makers to "fine tune their char making stove
system" to maximize char production. "The Stove Test should test the Stove
Device submitted for testing, and should report on what it found." It should
be up to the Promotional Char-makers to add the "Yes buts...", like "Yes
the overall stove efficiency is low, but look at all the char it
makes."</FONT></STRONG><FONT face=Arial></FONT>
<DIV><BR> <B> In a good stove, we are apt to see E2= 3,
E3= 4, and only 3 lost (lets label this Elost.) I want
those promoting the E3= 4 in char energy to be proud of, and promote, the E2=3
in cookpot energy. Way too much char is now being produced with
E2=0.</B></DIV><B></B></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"><FONT
face=Arial><STRONG># That may be fine for Customers wanting char, but a
"stove" is a device intended primarily for cooking and/or heating. Consider
the case of a mal-functioning wood pellet stove intended for space heating.
Assume its flaw was that it blew the charred pellets out of the combustion
zone and into the ash pit. With your proposed Efficiency Rating, the ash
pit carbon loss would be given full credit for having been burned, as it would
have been burned in a properly functioning pellet stove. Your "Energy
Efficiency Rating System" would cause great confusion.</STRONG></FONT>
<DIV><BR><BR><STRONG> Note I intentionally did not drop the
E2 value as I increased E3. Some char-making stoves are claiming that is
possible. So my (not-to-be-calculated) E4 would be 0.7. To stop
forest degradation we have to emphasize this combination is
possible]</STRONG></DIV>
<DIV> </DIV>
<DIV><STRONG><FONT face=Arial># The purpose of a stove is Cooking and/or
heating, not saving forests. However, "saving forests" is best done by
using efficient wood burning stoves, or by designing stoves that burn "waste
sourced" fuels. A well designed stove burning wood completely is
inherently more efficient than one producing
char. </FONT><BR><BR></STRONG><BR>Now let’s say the remaining char is
burned in a charcoal stove with 50% efficiency, then 1 MJ goes into the
cooking process and 1 MJ is “lost.” Then we could calculate a cooking
process efficiency for the system (including the char-producing stove and
char-burning stove): ( 3 + 1 ) / 10 = 0.4<BR>
<B>[RWL7: I have no problem with this, which we can call E5.
What I would object to is always trying to put the char back in the same stove
where it was made. Or if that is somehow mandated, at least also do a
"best" different char-using stove as well, for what we call E5.
Call the char combustion in the same (non-optimum) stove combination E6.
That is apt to be in your example about
E6=(3+0.5)/10=0.35]</B><BR> <B>I defend being able to
combine apples (carbon neutrality) and oranges (carbon negativity) because
they are at least equally important (I am leaning towards
oranges).</B></DIV><STRONG></STRONG></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"><STRONG><FONT
face=Arial># If the remaining char is going to be burned, rather than have to
go to the trouble of having to "re-burn" it, why not simply purchase a stove
that that burns it efficiently the first time through?? </FONT> <FONT
face=Arial>Your objection about putting the char back into the same stove from
which it was made is a serious one... this implies that the customer would
have to buy a second stove to burn the salvaged char. At any rate, each
stove should "rise or fall on its own merits". Where the char was burned
in the stove that made it, the same procedure could be used, and the results
reported as a second test, because it used a different fuel. </FONT></STRONG>
<DIV><BR><BR>For char-producing stoves, we plan to report:<BR>- Thermal
efficiency per the WBT (remaining char gets full credit as unused potentially
available energy)<BR> <B>[RWL8: I don't mind
this (assuming this is E1). But I could not define what this
efficiency means as it is not in the "standard" form of E2 and E3. In
your terms, we have "bananas". (I avoided the word
"lemons")</B></DIV><B></B></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"><STRONG><FONT
face=Arial># Jim: If the stove test is to rate the particular stove for its
"energy utilizing efficiency", then the energy in the char is "energy lost
from the stove", and "energy unavailable for cooking/heating". In a Boiler
Efficiency Test, "ash pit carbon loss" is treated as an energy loss from the
test... what is the rational to justify not counting the char production as a
"stove Loss"?</FONT></STRONG><FONT face=Arial></FONT>
<DIV><BR><BR>- Thermal efficiency for the “discarded” char scenario
<B><BR> [RWL9: E2.</B> <B> Fine. It helps
to compare with and note there is an E3. For sure, the
char-producing stove people will not want this called "discarded". How
about "cookpot-only"?]</B></DIV><STRONG></STRONG></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"><STRONG><FONT
face=Arial># If the char is not used as a fuel, the it is discarded from,
wasted, unused by the stove, etc. "Cookpot Only" could be construed as
"misleading advertising", in that it does not warn the Customer he will have
to dispose of unused char.</FONT> </STRONG>
<DIV><BR><FONT face=Arial><STRONG># Note that if the char produced by such a
stove is used as biochar, having no fuel value, it is inappropriate to credit
it with a fuel value in stove Efficiency tests.</STRONG></FONT></DIV>
<DIV> <BR>- Thermal efficiency for char production <B><BR>
[RWL10: This (E3) is fine, and all I am asking for.
It is already the subtracted portion of the denominator in the E1 computation,
so no new work is required.<BR> No need to
compute an E4 = E2+E3, - but I don't see how you can prevent people from
thinking it. What we want to be sure to warn against is combining E1 and
E3.</B></DIV><B></B></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"><STRONG><FONT
face=Arial># As noted above the concept of "Thermal Efficiency for Char
Production" is faulted. Any expression containing this term will be faulted
also.</FONT></STRONG><FONT face=Arial></FONT>
<DIV><BR><STRONG> I don't see any value in your
carrying out experiments to determine an E5 and/or E6 - which is what I
perceive Crispin to be proposing. Anyone wanting such numbers can put
them together readily from your data from char-using stoves. If you
decide to do testing to find an E5 and/or E6, I'd like another chance to
discuss this further - especially if any testing can't acknowledge some users
will want their stove to make char to sell or put in the ground (and not to
burn).</STRONG></DIV><STRONG></STRONG></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV><STRONG></STRONG> </DIV>
<DIV><STRONG><FONT face=Arial># I would suggest that this is a case of "the
Tail wagging the Dog." The common conception of "Stove Fuel
Efficiency" by Stove Customers and users is:</FONT></STRONG></DIV>
<DIV><FONT face=Arial><STRONG> "For every 100 units of energy I put into
a stove, X% is used to provide a desired cooking and/or heating
function." Why not employ a Stove testing Protocol that most customers
and users can already understand? The "Char Making Stove Community" could
adapt the "commonly understood" test results as required by the "Promotional
Char Makers". </STRONG></FONT></DIV>
<DIV><BR><STRONG> I have no problem with you (anyone)
testing a char-making stove to consume all the char. I would just not
then call it a char-making stove.</STRONG></DIV>
<DIV> </DIV>
<DIV><FONT face=Arial><STRONG># If it makes char, why not call it for what it
is?</STRONG></FONT></DIV>
<DIV><FONT face=Arial></FONT> </DIV>
<DIV><STRONG> You will get really awful results if you try to stop any
test part way and weigh an intermediate amount of char with most (any?)
char-making stoves.</STRONG></DIV><STRONG></STRONG></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"><STRONG><FONT
face=Arial># Agreed. If the Customer does not want the char, he should buy a
stove that does not make it in the first place.</FONT> </STRONG><FONT
face=Arial></FONT>
<DIV><BR><STRONG> You and Crispin are now in some
disagreement I think - as I believe he wants to have other data than you have
mentioned in this note. I haven't thought this all the way
through, but I don't think much new will come out of hs proposed new testing -
in a comparative sense. There might be some theoretcal value I have yet
to see, but the amount of testing work seems excessive, with no benefit to
users that I can see. As above, I hope we can have further
discussion on adding anything along the lines of his last memo, if the testing
involves something new relative to the handling and reporting of char
production.</STRONG></DIV><STRONG></STRONG></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV><STRONG><FONT face=Arial># I am in favour of any stove testing protocol
which:</FONT></STRONG></DIV>
<DIV><STRONG><FONT face=Arial>1: Is scientifically based</FONT></STRONG></DIV>
<DIV><STRONG><FONT face=Arial>2: Clear in the meaning of various
terms</FONT></STRONG></DIV>
<DIV><STRONG><FONT face=Arial>3: Easily repeatable by different testing
agencies in different locations, yielding virtually identical
results</FONT></STRONG></DIV>
<DIV><STRONG><FONT face=Arial>4: Gives the Customer the information that will
enable him to pick the best stove for his needs.</FONT></DIV>
<DIV><BR></STRONG><BR>I think reporting these results will provide complete
information, and how others value the different efficiencies will depend on
objectives (saving fuel, producing char, or a combination of
both).<B><BR> [RWL11: Agreed. In sum, we
appear to be in complete agreement (because I am not now asking for E4
numbers to appear anywhere, and I never wanted E5 and
E6.]</B></DIV><B></B></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px"><STRONG><FONT
face=Arial># I feel it is fundamentally wrong to calculate the efficiency of a
char making stove by giving an energy credit for the unburned char. I feel
this very misleading, and that it gives a false impression of efficiency that
does not exist. I also feel that the term "Thermal efficiency for Char
Production" is a faulty concept. For Stove Customers want to produce char, it
is not helpful to rate char production in energy terms, but it would be
helpful to report the weight of char produced as a percentage of "Input Fuel
Weight"</FONT></STRONG><FONT face=Arial></FONT>
<DIV><BR><BR><STRONG> [RWL12: Both Crispin and I
have perhaps recently raised another issue about subtracting unburned wood
energy similarly to subtracting the char energy in the denominator of an E1
computation. It needs consideration in the Elost area - as that wood energy is
certainly not lost in char-making stoves. But that is a topic for a
different discussion</STRONG>.]<BR><B><BR> [RWL 13: I
have sometimes also mentioned that I would like to see a reporting in
carbon or carbon dioxide (kg) terms as well as energy (MJ) terms. I
believe the answers look a little better then for char-making stoves.
But I don't think this requires additional testing on your part, so we can
ignore for now. Aside: the "carbon apples" and "carbon oranges"
look more alike than their joule equivalents
.</B></DIV><STRONG></STRONG></BLOCKQUOTE>
<BLOCKQUOTE
style="BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
<DIV><STRONG><FONT face=Arial># One could probably write a book on the
features and benefits of every stove. However, it would be good if the Stove
Efficiency Test Report cound focus on the efficiency of fuel
usage.</FONT></STRONG></DIV>
<DIV><STRONG></STRONG> </DIV>
<DIV><STRONG>Best wishes,</STRONG></DIV>
<DIV><STRONG></STRONG> </DIV>
<DIV><STRONG>Kevin</STRONG></DIV>
<DIV><BR><BR>Best regards,a<BR>Jim<BR><BR><B>The same . Again
thanks -- Ron</B><BR>_____________<BR><BR>From:
rongretlarson@comcast.net [mailto:rongretlarson@comcast.net] <BR>Sent: Monday,
April 22, 2013 2:57 PM<BR>To: Discussion of biomass cooking stoves; Jetter,
James<BR>Subject: Re: [Stoves] FW: REQUEST for complete sets of raw data of
cookstove tests.<BR><BR>Jim and stove list:<BR><BR> 1. I
like all parts of your message below, but want to comment on this
sentence:<BR><BR> " Meanwhile, we (EPA) will report future results
per the current WBT protocol (energy in remaining char gets full credit in
energy calculations), and we will also report results for the discarded-char
scenario (energy in remaining char gets no
credit)."<BR><BR> I cannot concur that the "energy in
remaining char" is currently getting "full credit" (as you and I discussed in
Phnom Penh). An efficiency number emerges when the energy in the char is
subtracted in the denominator - but a much larger efficency number emerges
when the simple ratio of char energy over input energy is added to the cookpot
energy over input. I ask that the separate char/input and
pot/input energy numbers be added to the WBT data output.
<BR> I also hope someone can explain what the
present efficiency computation actually means - as it is so different from the
simple sum of the carbon neutral and carbon negative stove
efficiencies<BR><BR><BR> 2. I also feel that the testing for
air-controlled batch stoves needs be different from those only controlling
fuel supply. I am appending here a draft "memo" that follows one I
found for charcoal-using stoves. I think this (39 kB) fits within
the attachment rules given to us recently by list-master Andrew Heggie, but if
it fails, I will re-send through Erin.<BR><BR><BR> 3.
I will also respond to another message today from Crispin that suggests all
char produced should be later consumed. This may be helpful
addtionally - but the results for char only being intended for placement
in soil (as above in (1)) should still be highlighted (and is not
now).<BR><BR>Ron<BR></DIV>
<P>
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