[Stoves] cook stoves for Cameroon

Ronal W. Larson rongretlarson at comcast.net
Fri Sep 19 21:43:05 CDT 2014


Crispin and list

   	Very peculiar to me that you can’t imagine people wanting to make money by making char while cooking and then selling it.  Perhaps you have a citation for this view?

	It would be most helpful if you could send something (anything) on this CSI calculation methodology - which I have requested two or three times already and your promised once.

Ron	


On Sep 17, 2014, at 9:38 PM, Crispin Pemberton-Pigott <crispinpigott at outlook.com> wrote:

> Dear Huck
>  
> The last question first:
>  
> How much ‘tree’ do you need to cook?
>  
> That is the question. If you are cooking on multiple stoves one that makes charcoal and one that burns it, you can analyse that as a ‘system’ but remember that to evaluate them you have to do them separately.  A lot of conflict, actually, has emerged over this question because those who want to make charcoal-making stoves don’t want them penalised for being inefficient, even if they are. They bring a lot of arguments in favour of this or that aspect of a system of which the stove is a port. No problem – such arguments are reasonable when discussing systems, however your question is strictly about stove performance.
>  
> The way you phrased the question is the same as the way the UNFCCC phrases it – how much tree for how much cooking. The assumption is that less trees used for the same amount of cooking is more efficient.
>  
> When calculations are made, however, people frequently calculate the energy released, not the amount of fuel consumed and the two numbers are nearly always different. We are not burning gasoline. Cars do not make charcoal. ‘Leftovers’ can be a significant portion of the energy available,
>  
> As Prof Lloyd just remarked a couple of days ago, it takes a lot of work to get fuel and people are not crazy – they want to burn it before going out to get more.
>  
> It is for these reasons that het Clean Stove Initiative Indonesia (CSI-Indonesia) uses a calculation method that captures the amount of raw fuel needed to complete another test burn cycle. The energy in that ‘fuel consumed’ is determined. That is the energy available. The energy gained by the pot (including the heat gained by the pot material as it can be substantial) is determined over a cooking simulation. In the case of the CSI-Indonesia pilot the determination is made using the CSI-WHT (‘Water Heating Test’). This is an accurate measure of the energy gained by the pot – to within a few Joules.
>  
> Energy applied divided by energy drawn from the forest is the system efficiency, or ‘overall efficiency’.
>  
> Regards
> Crispin
>  
>  
> Hi All,
>  
> I found myself a little confused by the discussion. 
>  
> Not being expert in the field, this is how I would pose my questions:
> There is a certain amount of energy per kilogram of wood (I’m going to stick with wood for the moment rather than all biomass).
> When burned, some of that energy is realized and some is not, i.e. there is not complete combustion.  How complete is the combustion?  How much energy is released?  That would be the first measure.  I want this because it tells me about one component of the system and is useful for design.  It does not tell me the net result for the user.
> How much of the released energy goes into cooking?  That would be my next measure.  That should tell me what weight of wood people have to collect to cook their food.  It is worth noting that the amount of energy that goes into cooking is also affected by the pots and lids used as well as how they fit onto the stove.
> It is also important to know how much energy was expended to get the fuel and prepare it for use.  Some of that energy is human energy so it gets treated a bit differently and has a different impact.  For example, it doesn’t convert simply to climate impact (are humans low global warming gas emitters?).  If you cut up the fuel a lot and process it a lot there is a cost there.  I don’t know how that stacks up for gasifiers vs other stoves.
> Regarding charcoal.  I am presuming you can still use the charcoal.  I was, apparently erroneously, under the impression that gasifier stoves could continue to receive primary air and therefore burn the charcoal.  I actually liked that idea because it was simple and used most of the energy in the stove.  If you take the charcoal out of the stove you then have a couple of options for using it.  You can burn it in another stove, which has some appeal as you can do a different kind of cooking with it (e.g. BBQ, or ?).  But also seems like quite a bit of work and complication for a small amount of charcoal.  Or, you can use it in the soil. So another question:
> Is a gasifier stove with charcoal (biochar) buried actually carbon negative?
> Then the other important measure: what are the emissions?
>  
> And, a kind of crude question: with the ins and outs of this discussion is it the case that rocket stoves or some other stove is more efficient than the gasifiers?  In my question by efficiency I mean kg of wood required for a Cameroonian to cook their meals?
> Which stove do they have to carry more wood for and do more fuel preparation for?  (I’m not sure how you measure the combined work for those tasks).
>  
> Huck
>  
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