Dear Paul
----- Original Message -----
From: Paul Anderson
To: Discussion of biomass cooking stoves
Cc: Crispin Pemberton-Pigott ; [email protected] ; Ranyee Chiang
Sent: Wednesday, April 10, 2013 11:46 AM
Subject: [biochar] Efficiencies regarding wood, non-wood, and charcoal Re:
[Stoves] Alternative to charcoal
I posted to the list (copy below) an approach that I feel would sort out the
the difficulties you encounter when a reational science based stove testing
protocol is implemented. The fundamental problem comes when one attempts to
"force fit" all stoves into one category. Clearly, there are fundamentally
different stove types or technologies. No less a person than Dr. Tom Reed has
coined the concepts of "char producing", "char burning" tar producing" and "tar
burning" (Where "tar" refers to pyrolysis gases)
In my previous posting, I defined three fundamental categories of stoves:
1: A "Full Combustion Biomass stove", where all fuel is intended to be burned
to completion
2: A "Partial Combustion Biomass Stove", where char or charcoal is a desired
end product. (This charcoal can be subsequently used as fuel, or as biochar.)
3: A "Charcoal Combustion Stove."
1: Examples of a "Full Combustion Biomass Stove" would range from a 3 stone
fire to a Rocket stove. The fundamental characteriestics of such stoves are:
* They produce tar
* They produce char
* They burn tar
* They burn char.
2: The TLUD is an example of a "Partial Combustion Biomass Stove. The
fundamental characteristics of such a stove are:
* They produce tar
* They produce char
* They burn tar
* They DO NOT burn char
3: An example of a "Charcoal Combustion Stove" would be a Hibachi BBQ. The
fundamental characteristics of such a stove are:
* They DO NOT produce tar
* They DO NOT produce char
* They burn tar (if tar remained in the charcoal)
* They burn char
Clearly, the thee stove systems are fundamentally different. It is only
reasonable that different test protocols be adopted to highlight the features
for which each excel.
Clear also is the fact that some "End Users" (or Customers) do not want
residual charcoal, while others do indeed want a stove that produces charcoal,
either for subsequent use as fuel, or for use as biochar. "End Users" who do
not want residual charcoal should select a stove system from "Category 1",
while "End Users" who want a stove producing residual charcoal should select a
stove from "Category 2"
A stove is fundamentally a cooking or heating device. The simple fact of the
matter is that a stove producing char will require more input fuel than one
that burns it to completion, all other things being equal. A "Category 1" stove
is thus the best choice where the End user does not want char in the ashpit. On
the other hand, where teh End User does want char as a "stove byproduct', then
his best choice is a "Category 2" stove. It appears that is some locations, the
economics of char production are such that it will actually pay for a
""Category 2" stove system.
A good Testing Protocol for Category 2 stoves would be very helpful to those
wishing to have a source of char. The testing Protocol would show which was the
best producer of char, while still accomplishing the desired cooking or heating
function.
The good thing about science based tests is that they report the results in
numbers. They present "digitized results" rather than "fuzzy wordage.".
No one stove technology is the panacea. The "House of Stoves" has many rooms.
Appropriate testing protocols will allow the Customer to choose the stove
system that will best do the job he wants done.
Would you agree that different testing Protocols should be established for
the fundamentally different stove systems?
Best wishes,
Kevin
Dear Crispin, Ron Larson, and Stovers with char interests,
On 4/9/2013 12:18 AM, Crispin Pemberton-Pigott wrote:
<snipped>
If I put 1 kg of 15% moisture wattle (15.9 MJ/kg) into a TLUD stove and
create 20% char (20% of the moist mass) the net heat provided by the fire is 10
MJ/kg. The heat available from the char is still 29.5 so the total is the
difference the bit between: 15.9-10 = 5.9 MJ.
If someone wants to switch from wood fuel to a 'cleaner' TLUD and that TLUD
is not 1.5 times as efficient in transferring heat, their raw fuel consumption
will increase.
The numbers are correct, but the language is biased. "If...switch from
WOOD fuel..., their RAW fuel ..... " How about saying
"If switch from wood fuel stove to a TLUD that does not need to use wood
fuel, their wood fuel consumption could be eliminated."
Is the issue about WOOD or is it about efficiencies of devices (TLUDs) that
leave charcoal behind? Actually, both are important, but the norms of
reporting of stove testing with biomass fuels are too intimately connected with
wood because so many stoves are designed as only wood burners.
Let's stop criticizing or penalizing the TLUDs because they make charcoal.
And the new testing protocols/reports MUST have clarity of wording about
efficiencies without the innuendo that TLUDs lack efficiency because wood (if
used) is turned into charcoal.
Paul
*************************************
----- Original Message -----
From: Kevin
To: Discussion of biomass cooking stoves
Sent: Tuesday, April 09, 2013 11:54 PM
Subject: Re: [Stoves] Alternative to charcoal
Dear Dale
You raise excellent points about the desirability of finding an
"Alternative to Charcoal". I feel that the problem is both very complex, AND
very simple at the same time. The problem is very complex, when dealt with, as
a whole, but very simple when broken down into the various facets of the issue
that complicate it.
If we look at the "continuum" between wood as a fuel, and charcoal as a
fuel, we see that at the "Wood End" and the "Charcoal End", there is a clear
preference, need, or requirement for the respective fuels. In the center, there
is a "gray area", where either fuel can be utilized, to greater or lesser
advantage and disadvantage.
The problem is somewhat further complicated by those who see charcoal as a
"climate change tool" and superimpose climate change considerations on stoves,
perhaps even to the degree of relegating the fundamental heating and cooking
aspects of a stove to a secondary level of importance.
Everything starts with the biomass fuel... wood, grasses, agricultural
products or waste, etc. In the logic I am about to lay out, I state that there
are fundamentally three kinds of stove:
1: A "Full Combustion Biomass stove", where all fuel is intended to be
burned to completion
2: A "Partial Combustion Biomass Stove", where char or charcoal is a
desired end product. (This charcoal can be subsequently used as fuel, or as
biochar.)
3: A "Charcoal Combustion Stove."
In the interests of simplicity, I ignore "Charcoal Retorts", because of
their basic thermal inefficiency.... much of the pyrolysis gas energy is simply
vented. However, a retort that made use of the pyrolysis gas heat could be
termed a "Partial Combustion Biomass Stove.'
A major advantage of this approach would be that it would clearly
categorize stoves, and as a consequence, would allow for three different
testing protocols.Each Testing protocol could be set up to best capture the
performance parameters that were of most importance to each stove system.
Crispin's Proposed Stove testing Protocols are perhaps best for "Full
Combustion Biomass Stoves." Equivalently relevant protocols could be developed
for "Partial Combustion" and "Charcoal stoves.
I feel that the process should be "Customer Driven." If a Customer wants to
burn charcoal as fuel, then that is his decision. Or, if he wants to produce
charcoal, for resale, or for use as biochar, or for subsequent use as a fuel,
then that also should be his decision. This is where a good set of Testing
Protocols would be really helpful... they would allow the Customer to select
the stove system (or systems) that best met his needs.
Note also that when fundamental "performance information" was available
from the above three protocols, it would be very easy to develop a spread sheet
that factored in all the relevant information, so that the Customer could make
a rational decision on what would be the best stove system for his particular
circumstances.
Best wishes,
Kevin
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