[Stoves] Analysis of emission profiles from charcoal produced from selected tree species by different pyrolysis methods

[Nikhil Desai]

Teddy:

Yes, both can be done on scale - trees can be grown and combustion
efficiency can be improved; the question is, what is the marginal cost of
either?

Combustion efficiency is but one part of cooking operations in a restaurant
or at home; capital costs of stoves, fuel storage and ash disposal systems
are factored in, as also the location and running costs including labor and
fees/taxes. Most importantly, a stove or a broiler is chosen for providing
the desired service at a certain temperature and volume profile. Higher
combustion efficiency may have declining returns or a plateau, and a new
stove will not be purchased if the overall cost of replacement or addition
does not match the required service standard and savings in fuel costs.

Similarly, growing trees is not without cost. There is a cost - or
opportunity cost - of land, water, manual care, and equipment to cut and
haul trees and branches. Then come the charcoaling part.

At the margin, even if the same person or company owned the combustion
device as well as the trees, there IS a tradeoff between growing the
feedstock and higher efficiency; the calculations get complicated if one
introduces the element of time, discount rates, and so on. Traded charcoal
gives a good price signal - at what charcoal price do I want to invest in a
stove system that has 10% higher combustion efficiency? Where charcoal is
not purchased but made on site with own feedstock, one should ask how much
that charcoal could fetch in the market.

This kind of consumer choice is better representation of reality than the
physicists' obsession with sustainability beancounting and efficiency. In
more areas than one - from cookstoves to electricity - I think the hallowed
false gods of efficiency and renewability have done more damage than good
to the poor.

Blind science sucks. Scientists need to observe and listen more, model
less.

Nikhil


------------------------
Nikhil Desai
(US +1) 202 568 5831
*Skype: nikhildesai888*


On Sat, Mar 9, 2019 at 12:10 AM Cookswell Jikos <cookswelljikos at gmail.com>
wrote:

>
> Thanks Nikhil,
>
> How do you mean by this *''**There is always a trade-off between growing
> the charcoal feedstock versus burning charcoal with higher efficiency''*
> can both not be realistically achieved on scale? We know of a few
> restaurants/BBQ joints here who do both.
>
> *Best, *
> *Teddy *
>
>
>
>
>
>
>
>
> On Fri, Mar 8, 2019 at 5:20 AM Nikhil Desai <pienergy2008 at gmail.com>
> wrote:
>
>> Teddy:
>>
>> Do you know carbon sequestration profiles of different tree species and
>> crops?
>>
>> How does one address the issue of PAHs as an interim product to CO2,
>> which is good, versus direct emissions of PAHs, for which there is no GHG
>> computation?
>>
>> I suppose efficiencies are in some way linked to the shares of PAH and
>> CO, CO2 in the combustion process, so that a higher-efficiency stove would
>> produce fewer PAHs but greater CO2. If one were to address GHG-neutrality
>> only in terms of CO2, this would seem to frustrate the desirable goal of
>> more complete combustion.
>>
>> There is always a trade-off between growing the charcoal feedstock versus
>> burning charcoal with higher efficiency. And if a stove were selected on
>> the basis of higher efficiency rating as well as lower CO2 emission rates,
>> it is by no means certain that it would succeed in real circumstances.
>>
>> Nikhil
>> ---------------------------
>>
>>
>>
>>
>> On Thu, Feb 7, 2019 at 12:48 AM Cookswell Jikos <cookswelljikos at gmail.com>
>> wrote:
>>
>>> Good morning all,
>>>
>>> Being a big proponent of growing more of these types of indigenous trees
>>> for charcoal in Kenya (we include free seeds with each stove purchase) I am
>>> happy to see this report on the different emission levels from various
>>> types of charcoal.
>>>
>>> How different emissions from charcoal would affect the taste of food is
>>> anyone's guess, but it does lend credence to stories I have heard of why
>>> chefs in the Middle East etc. insist on importing tons of illegal acacia
>>> charcoal from Somalia.
>>>
>>> More tests on the dozens of other species of local trees that are
>>> preferred for firewood/charcoal would be most interesting to read if anyone
>>> has any that they could share.
>>>
>>> *''All the charcoal from the three tree species under study emitted
>>> similar types of PAHs but at significantly different concentrations. A.
>>> xanthophloea charcoal prepared by efficient pyrolysis emitted the least
>>> concentration of PAHs. Thus, according to this study, using charcoal
>>> produced from  A.  xanthophloea by efficient pyrolysis presents a better
>>> opportunity to reducing exposure from PAHs emit-ted from biomass fuels.''*
>>>
>>>
>>> https://link.springer.com/epdf/10.1007/s13762-019-02220-x?author_access_token=XDpVhLZRgWpLPgeDkoTvCfe4RwlQNchNByi7wbcMAY4TAzk706nlQbkDAKP1sFLIg30j6XGmh3a8qNepBVgX9Ho3rnVR3Bwh6UKPAk0PXABQcXH3pMGCxPXZphBhoV3PlFv8BcLjbyaIt4xOVZKisw%3D%3D
>>>
>>> Teddy Kinyanjui
>>> Sustainability Director
>>>
>>>
>>>
>>>              <https://www.facebook.com/CookswellJikos>
>>> <https://www.instagram.com/cookswelljikos>
>>> <https://twitter.com/cookswelljikos?lang=en>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20190310/95df6659/attachment.html>