[Stoves] stoves and credits again

[Ronal W. Larson]

Andrew and list:

	I think we are in agreement on all but your last response, where I and you say:

>> `Andrew - thanks for your above rebuttal to Crispin.
> 
> Ronal I don't see it in those terms. Crispin has a different viewpoint
> but his goal is the same in promoting clean cookstoves.


	RWL:  Afraid I can’t agree.  

	I can remember no Crispin statement ever in support of char-making TLUDs, which all data shows are the cleanest.  Plenty of Crispin support for cleaner stoves using coal - which I claim can never be justified - for both health and climate reasons.

	His continued fighting against the equation e3 = e1/ (1-e2) is my major concern.

Ron



> On Sep 22, 2017, at 3:26 AM, Andrew Heggie <aj.heggie at gmail.com> wrote:
> 
> On 22 September 2017 at 03:54, Ronal W. Larson
> <rongretlarson at comcast.net> wrote:
> 
>> Andrew wrote
>> There might be a slight case for saying a
>> gasifier stove can achieve  a lower massflow (particularly lower N2)
>> because the primary combustion doesn't go to completion so less
>> primary air is used,  the corollary may be that the secondary flame
>> also can be burned with less excess air because the offgas has a
>> higher calorific value but not enough to make up for using 50% less
>> energy..
>> 
>> 
>> [RWL2:  Given my response in “1” - I need to address the term “50”
> 
> Ronal I clarified this in my reply to Paul, obviously it is subject to
> experimental measurements but from a desk study given that the char is
> reacted at 600C AND 20% of the original biomass dry weight remains as
> char then it looks like the energy remaining in the char is closer to
> 1/3 than 1/2 of the original energy in the dry wood.
> 
>> Andrew:  I am not understanding your last 15 words.
> 
> 
> Partially dealt with above but also what I was meaning was that  the
> offgas from a TLUD, with just sufficient primary are to maintain the
> descending pyrolysis front, will be largely the pyrolysis offgas plus
> the small amount of gases from the combustion that provides the heat
> to drive the process. So it will be little diluted by CO2 and nitrogen
> than from a traditional fire which supplies enough under grate
> (primary) air to completely burn out the char. Hence the offgas from
> TLUD is of a higher calorific value and as such needs less  excess air
> to maintain a clean flame. On a larger scale with lower heat losses in
> the primary region this may not be the case.
> 
> 
>> 
>> Disagree with Crispin’s statement that a case with 25% char retention
>> involves “50% of the original energy” (as did Paul Anderson).
> 
> Also dealt with but we need corroboration from analysis of TLUD char.
> 
> 
>> Agree with most by Andrew - but think the last sentence needs amplification.
>> That is  - lower temperature char can be a better economic choice, even if
>> “fixed carbon retention” is less.  This is better discussed on the biochar
>> list.  pH value is one criterion that could point toward lower T’s.
> 
> ...and of course lower fuel input cost would make it more economic
> even if the carbon credit paid to the producer were based solely on
> the fixed carbon.
> 
>> 
>> [RWL7:   I have seen NO data to show that LPG stoves do not
>> have lower emissions than any solid fuel stove.
> 
> It seems unlikely to me that simple stoves could have lower emissions
> than a LPG flame but Crispin did say as near as makes no difference
> and good enough works for me.
> 
> 
>> Andrew
>> The trouble is I have a
>> parochial view and not a good worldview of what types of persons
>> depend on biomass fuelled stoves. Are they also predominantly growers?
>> 
>> 
>> [RWL9:  Yes to Andrew’s last question.  I disagree with Andrew calling
>> himself “parochial” - when he supports (as do I) the ethics of “a subsidy
>> funded by the developed world”.
> 
> I was referring more to my lack of experience of stoves in the real
> developing world compared with yourself, Crispin, Nikhil and many
> others.
>> 
>> 
>> So my contention is that apart from the carbon credit there is a value
>> to the land in not having to export a cash crop.
>> 
>> 
>> [RWL10:   Agree totally.
> 
> It still means the grower needs to recognise that exporting a
> conventional cash crop is removing mineral wealth from the holding, in
> many soils with high initial fertility this may not be significant. So
> whilst the cash that the grower/stove user might receive will be
> linked  to the carbon credit paid for using the resultant char as a
> soil amendment he might also value not having to use the land for a
> cash crop and possibly growing stove fuel.
>> 
>> `Andrew - thanks for your above rebuttal to Crispin.
> 
> Ronal I don't see it in those terms. Crispin has a different viewpoint
> but his goal is the same in promoting clean cookstoves.
> 
> Andrew
> 
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