[Stoves] Definition of char-making appliance

[rongretlarson at comcast.net]

Crispin cc "stoves" 

See below. 
----- Original Message -----
From: "Crispin Pemberton-Pigott" <crispinpigott at gmail.com> 
To: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org> 
Sent: Monday, May 6, 2013 10:06:54 AM 
Subject: Re: [Stoves] Definition of char-making appliance 




Dear Ron 



Stove testers are not carriers of opinions on social benefits, that is for regulators. This definition is for an ‘appliance’ because that is the correct term for a ‘device’ used for cooking. 


[RWL1: S o is the word "stove" used - and is so used by GACC. They use the term " stove ", not "appliance" i n 4.2.2. 




They are in fact domestic appliances in this case. A toaster is not a stove. A kettle is not a stove. They are cooking appliances and will be regulated. 

[RWL 2 : So you a re con firming my guess that you are trying to separate the words "charcoal-mak ing" and "stoves". That is not the case now and I ask why you want to not call a CMS (Charcoal Making Stove) a stove, but rat her (I gather) a CMA ? 








> The number 15 % could be useful. I can't think of a better number, if we need this, since 15% is easy to achieve. 

I chose the number because it is easy to achieve and I want to eliminate stoves that are just ‘lousy burners of the fuel’ like the so-called Namibian Tsotso. They may or may not produce copious amounts of partly burned wood. That is not a char making stove, in my view. 

[RWL 3: Does the tsotso make 15% char ? Whether any particular stove does or doesn't perform well shouldn't be part of this discussi on. If the T s otso is a critcal example of bad testing of charcoal-making stoves (CMSs), I hope you w ill explain why.] 





> I would make NO or LITTLE distinctions in the way 4.2.2 tests are performed and reported for char production above or below 15%. 

I sense you angling for some additional ‘benefit’ to accrue to a stove that produces biochar. The test only reports what happens, it does not have opinions on what the products are. The mass of char is already recorded (has been for ages) but it was not reported. The only difference is to report it. At the moment the WBT uses the mass of char, not the carbon content. 

[RWL4 : I think you probably can g et the carbon conte nt fr om the bomb calorimetry tests on all (?) input and output wood/biomass and char quantit i es. The important point is that they (Jetter, Still etal) already do calculate and use the ener gy in the char (which includes the important impact of hydrogen). I am only ask ing that they also rep ort that ENERGY number separately - since many people are interested in that number. We ights and carbon content are important - but not as important as energy, when the IWA g roup divisions depend so stro ng ly on energy, not carbon cont ents, e te. If that means I am angling for something, I plead guilty. 


I take it you disagree with my above sentence about distinctions in reporting 4.2.2 res u lts above and below 15%? You don't wan t that? You want w hat difference? ] 


I am tightening that definition a little to counter the possibility that ‘cheating’ may be seen with respect to high ash fuels like palm fronds and rice hulls. If it is being ‘rewarded’ as a biochar or charcoal fuel producer, ash can’t be slipped in as a qualifying product. 

[RWL5: I guess you are suggesting that test 4.2.2 reporting is too loose. I don't see that at all. Ash is now getting zero credit for anything.] 


The reason I am being careful is that the formula for fuel efficiency is tilted slightly towards char making stoves in that they are not ‘fully punished’ for using slightly more fuel provided the char production rate is high enough. The mechanism is to give a fuel efficiency (heat energy in the fuel to heat in the pot) then require that char making stoves achieve that % plus the rate of char produced. For example if the target is 30% fuel efficiency, and a stove makes 20% char by dry mass calculation, it will have to have a heat transfer efficiency (not a fuel efficiency ) of 30+20 = 50% in order to be accepted. This is slightly advantageous to the char maker in terms of fuel consumption. At a 25% char production rate it is an advantage (a forgiveness) of 10% of the fuel consumed. 

[RWL6: Hmm "fully punished". H mm 

My understanding is that the efficiency number has been a nd st ill is the ratio of pot energy divided by (input fuel energy minus char energy). I do not believe it is as you desc ri be. I believe this formula is slightly tilted away from (is not fair to) char-making stoves - probably because hydrogen values are left out. But I am accepting th at formula. I only want to also let people know how much e nergy is in the char. That number is already bei ng calculated. 


In your descripti on above, you seem to be using 20% char by we ight directly in an equation for energy ratio s. M akes no sense. ] 

If anyone needs a more stringent explanation of this I can provide it. 

[RWL7: I need it - given to the whole list . W ith the specif ic equat ion numbers from the 4.2.2 procedures with which you disagree. Example faulty calculat ions are needed, We want to be sure we punish where appropr iate. Ron] 


Regards 

Crispin 


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