[Stoves] Energy in different fuels

[Paul S. Anderson]

Crispin, Tom and all,

Thanks for the wonderful replies.  And let's not overlook the wonderful
"convert.exe" program that Tom lead us to a couple months ago.  (I have it
installed, but no longer have the URL to getting it.)

Crispin's comments lead to the correction of the Ethanol value to be 32 MJ/kg
instead of Tom's value of 27 MJ which was per litre.

I am saving only the 2-digit values because everything seems to have 
some small
fluxuations.

Fireballs will have the MJ/kg in proportion to their content (including 
moisture
levels), so leaf-litter fireballs that are dry will be about 13 MJ/kg.  But if
50% charcoal by weight, the fireball value would be about 20 MJ/kg, plus or
minus 1 MJ/kg (5%) would hit it pretty close.

Interesting that charcoaled briquettes are 2 units higher than straight
charcoal.  I would have thought that the amount of binder would have reduced
the energy value.

To Richard:  I and most others agree with your comments about the 
importance of
getting the heat to the pot, but unless we know the heat values of the raw
fuels, we cannot tell if 150 grams of charcoal doing the WBT (water boiling
test of "boil-time + 45 min simmer") is better, same or worse than some other
fuel with xxx grams doing the same test.

Interesting:  Said this way (above), the total time of the WBT (regardless of
being fast to boil or taking much time) is not a factor in the comparison of
required energy, BUT "time to boil" might be the deciding factor in what the
cook is willing to accept.

Further:  NO fuel is free from energy needed to have the fuel ready for use in
the kitchen.  Dung must be collected, pattied, dried, and transported. 
Charcoal is a form of processed wood.  Alcohol from biomass is 
processed.  And
electricity, well, extremely expensive to produce.

Do we have a table of values of energy costs (and labor costs??) to have these
diverse fuels available to the kitchen?  The answers will not be so easy for
this question.  This opens the discussion to whether the biomass for making
ethanol is grown using expensive fertilizers and equipment + fuel, or is the
ethanol from a micro-distillery with low value biomass?  And how is the
charcoal made, as the principle product or as a co-product when the pyrolysis
gases are well used?

For starters, I am just trying to get GENERAL values.  I am interested in the
preparation costs ("effort") of the main fuels for cookstoves.  Perhaps 
for the
basic fuels of ag residues and firewood and dung, we just have an unknown but
considered-to-be-about-equal value of "X effort".  This is reasonable because
if the effort for the local people gets to be too great, the people shift to
the other types of low value fuels.  Many already do this on a seasonal basis
depending on what fuel is available.

But for the more processed fuels, part of that same "X effort" value is needed
PLUS the processing/preparation costs or efforts of those who prepare 
the fuels
as a vocation/business, whether as an isolated charcoal maker or as a
substantial business venture.

I am not on the biomass conversion listserv or other "fuels" lists, and I know
that the discussion probably belongs mainly there, and has probably been done
there already.  BUT for STOVES comparisons, can we get some general values
posted here, please?  Because charcoal is a hot topic of discussion currently,
we should be able to compare it to kerosene/parafin and to ethanol.

Paul

-- 
Paul S. Anderson, Ph.D., Geography professor - Emeritus
Telephone:  USA-309-452-7072 (residence and office)
Internet site:  www.ilstu.edu/~psanders
For my gasifier stoves info, go to:
http://bioenergylists.org/contributors#Paul_Anderson


Quoting Crispin Pemberton-Pigott <crispin at newdawn.sz>:
(snipped)
>
> Ethanol alcohol 31.8 MJ/Kg
> Ethanol alcohol 26.7 MJ/Litre
> Ethanol with 5% water (which is the normal water content of distilled 
> ethanol)  24.5 MJ/Litre.  Gel fuels are typically 5% water + the gell 
> and denaturing agents, giving about 24-25 MJ/Litre but often the 
> literature claims it is 30 MJ which is the heat per Kilogram, not per 
> litre. I have a particular bone to pick about this because the stoves 
> are often compared with paraffin fuel heat measured in litres and 
> alcohol fuel heat measured in kilos.


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