[Stoves] stoves and credits again
Ronal W. Larson
rongretlarson at comcast.net
Sat Sep 23 16:20:33 CDT 2017
List, Paul and Philip:
Phil is quite justified in introducing new nomenclature, but I think others may find mine easier, so I do a translation below. The names will make no difference in the conclusions below.
> On Sep 23, 2017, at 12:37 AM, plloyd at mweb.co.za wrote:
>
> Thanks. It is easy and logical and sound:
> Cook = Ucook/Rfuel
Could be my e1 in the WBT, but see “Hot”; in the WBT there is no cooking, only water heating
> Echar= Uchar/Rfuel
Same as my e2; As an example, we can both say this value is 1/3; a common number for the WBT
> Espace = Uspace/Rfuel
This is zero throughout the WBT, which is the topic under discussion
> Hot = Uhot/Rfuel
Same as my e1; In my example, e1 = 1/3, also not far off reality. This is the 5 liters of H2O in a pot.
> E = (Ucook+U char+Uspace + Uhot)/Rfuel
I am using e3’ for this; Philip will obtain e3’ = 1/3 +1/3 = 2/3; using my numbers appropriate to the WBT; I call the remainder ei - the inefficiency. (1/3 here)
> Where E is efficiency,
I have named efficiency as both e3 and e3’, where e3=e1/(1-e2), and e3’=e1+e2; respectively 1/2 and 2/3 in my hypothetical
> U is useful energy
I have named this e1+e2, but dropping Philip’s Ucook and Uspace - which are not measured in the WBT.
** This line is a big difference between us; I do not assign Uchar = e2 (= 1/3) to be useful in a cooking test.
** My guess is that Philip will backtrack on this point re the WBT under discussion
> R is raw fuel energy
I have assumed everything normalized to R =1 energy unit (could be MJ or BTU, etc)
> cook is for cooking
I’ve dropped; not in the WBT
> char is for char production
I’m using “2” as in e2
> space is for space heating
Dropped as not being in the WBT
> hot is for hot water production
I’m using “1” as in e1
>
> So you have a single equation that can give an loverall efficiency for stoves providing different services, or can give the efficiency for each of those services. The moment you try anything logical with less input energy because you are producing an energy service, intuition proves a poor guide.
So Philip, in the reduced form for the WBT, is saying he prefers e3’ (the 2/3 value). I am preferring the smaller number e3, where e3 = e1/(1-e2) =(1/3)/(1-1/3) = 1/2. Since this dialog (about ISO and WG2) is all about Tiers, I think Philip will find his perspective will not be appreciated by his cohorts from South Africa; Biochar will be winning by even more than it already is.
Remember the WBT is simulating cooking - in no way is much of the discussion about char-making; this is why e3 is there, not e3’. But if Philip wants to assert that the right efficiency number for the WBT (and Tiers) in his above (my e3’), no one interested in biochar will mind.
I see no need to add to Paul Anderson’s note below. I think (not sure) that Paul is supportive of the present WG2 methodology with its (1-e2) in the denominator - giving my e3 (1/2) over Philip’s preferred e3’ (2/3).
Ron
> Philip Lloyd
> Sent from my Huawei Mobile
>
>
> -------- Original Message --------
> Subject: Re: [Stoves] stoves and credits again
> From: Paul Anderson
> To: Discussion of biomass cooking stoves
> CC:
>
>
> Philip,
>
> Good. Let's move this forward.
>
> Please provide the equation that puts char (that is, the energy in the char) above the line in a way that recognizes that it is not a loss of energy, it is only a transformation of the energy that is in the fuel.
>
> Or say it some different way and show it as being of value in the equation that is to be provided.
>
> Crispin and I have long ago come to agreement that energy efficiency is not the same as fuel efficiency.
>
> Paul
> Doc / Dr TLUD / Prof. Paul S. Anderson, PhD
> Email: psanders at ilstu.edu <mailto:psanders at ilstu.edu>
> Skype: paultlud Phone: +1-309-452-7072
> Website: www.drtlud.com <http://www.drtlud.com/>
> On 9/22/2017 12:28 PM, plloyd at mweb.co.za <mailto:plloyd at mweb.co.za> wrote:
>> His continued fighting etc etc. What nonsense - the equation is wrong, spurious, faulty, unscientific. Efficency is the useful energy produced divided by the fuel input. Char is not an input but a PRODUCT. Therefore it goes above the line in any efficiency calculation. You cannot subtract it from the feed, because it is a product ( positive) and not a negative feed. Please stop trying to use bad science to justify an untenable position. It gives the whole of stove science a bad name when the scientific illiterati try to justify their abuses.
>> Philip Lloyd
>>
>> Sent from my Huawei Mobile
>>
>>
>> -------- Original Message --------
>> Subject: Re: [Stoves] stoves and credits again
>> From: "Ronal W. Larson"
>> To: Discussion of biomass ,Andrew Heggie
>> CC:
>>
>>
>> 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.
>> Y t.v.
>> Ron
>>
>>
>>
>> > On Sep 22, 2017, at 3:26 AM, Andrew Heggie wrote:
>> >
>> > On 22 September 2017 at 03:54, Ronal W. Larson
>> > 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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>> >
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