[Stoves] cook stoves for Cameroon

Huck Rorick huckrorick at groundwork.org
Wed Sep 17 21:27:52 CDT 2014


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:

1.	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).
2.	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.
3.	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.
4.	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.
5.	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:
6.	Is a gasifier stove with charcoal (biochar) buried actually carbon
negative?
7.	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

 

From: Paul Anderson [mailto:psanders at ilstu.edu] 
Sent: Monday, September 15, 2014 9:25 PM
To: Discussion of biomass cooking stoves
Subject: Re: [Stoves] cook stoves for Cameroon

 

Huck,

Crispin wrote:



Thus 'gasifiers' are getting rated as if they do not consume fuel that is
actually consumed.

Crispin's point is that wood that is turned into charcoal is no longer wood.
THAT is true.    But there are two ways to state the efficiency:    Fuel
efficiency and Energy efficiency.    Charcoal that is created is no longer
wood.   But it is a fuel made from wood that was transformed.    And it
typically represent 25% to 35% of the energy that is in the dry weight of
the wood.  

You indicated that the area is reasonably wooded.   So it is not a case of
scarcity of wood.   

If the created charcoal is put into the soil as biochar, then that energy
content is no longer available.

You as the project leader and with your personnel can make the decision
about how to read the numbers in the reports on stove efficiency (of fuel or
of energy).

Paul




Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD  
Email:  psanders at ilstu.edu   
Skype: paultlud      Phone: +1-309-452-7072
Website:  www.drtlud.com

On 9/15/2014 10:45 PM, Crispin Pemberton-Pigott wrote:

Dear Huck

 

Just one quick point:

 

"The gasifier, as I understand it, is more efficient and has lower
emissions."

 

It depends on the test method and the metrics. It is fashionable to use the
GACC-WBT and that test does not report fuel consumption, it reports the fuel
mass equivalent of the energy consumption, treating charcoal left over as
unburned raw fuel (meaning it says the wood was not consumed).

 

Thus 'gasifiers' are getting rated as if they do not consume fuel that is
actually consumed. When you assess the performance be sure you are clear on
how the method calculates performance and what the metrics are. You may want
to measure ( and weigh) fuel needed per cooking cycle rather than use any
calculated numbers from a complex test protocol.

 

For evaluation of performance I recommend the CSI-WHT which is a water
heating test (no boiling) and a measure of the raw fuel needed per
replication of the cooing cycle. It is used by the WB in the Clean Stove
Initiative in Indonesia. Documentation (some anyway) is available.

 

Regards

Crispin in Tamil Naidu

 






_______________________________________________
Stoves mailing list
 
to Send a Message to the list, use the email address
stoves at lists.bioenergylists.org
 
to UNSUBSCRIBE or Change your List Settings use the web page
http://lists.bioenergylists.org/mailman/listinfo/stoves_lists.bioenergylists
.org
 
for more Biomass Cooking Stoves,  News and Information see our web site:
http://stoves.bioenergylists.org/
 

 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20140917/9d5c3074/attachment.html>


More information about the Stoves mailing list