[Stoves] Understanding FUEL EFFICIENCY vs Energy efficiency

[Paul Anderson]

Dear Stovers and Biochar makers,

We are NOT sufficiently emphasizing that TLUDs/char-maker stoves can use 
fuel other than stick wood.   When burning briquettes and pellets and 
cobs and shells (which most other stoves cannot burn very well), we are 
NOT burning tree-sourced fuel.

Crispin correctly says that a kg of wood in and pyrolyzed is no longer 
wood, and therefore is FUEL used, and that relates to FUEL Efficiency. 
    TLUDs can consume more wood because they are converting some of that 
wood into charcoal.    That is different from ENERGY efficiency, which 
can allow calculations for the energy in the charcoal that is not used.

Especially in char-making stoves, energy efficiency is better than the 
fuel efficiency IF USING WOOD.   But if the fuel is not wood, then the 
WOOD-FUEL efficiency is 100% (none was burned in the cooking of the 
meal), and the ENERGY efficiency might be very good, while the FUEL 
efficiency (burning ag residues, dung, etc) might be low in comparison 
with other stoves, but no trees were cut or burned.

About the above, there will need to be some education given to the stove 
community (including GACC and manufacturers and governments). WHAT fuel 
is burned does make a difference if FUEL efficiency is an important 
criteria when evaluating stoves.

Just because wood is the traditional fuel used in stove testing does not 
mean that stoves that can also burn OTHER biomass should be judged on 
the WOOD-FUEL efficiency calculations.   For places like Haiti, Rwanda, 
and many large zones of numerous large countries, to be able to cook 
WITHOUT FOREST DEGRADATION should be a major reason for choosing TLUD 
stoves.

Having written about this here does not mean that the message has 
reached the decision makers and those who report test results on 
cookstoves.   And the makers of "stick-wood-burning stoves" are unlikely 
to want to tell this message to others.

Because the GACC is about stoves AND FUELS, I hope that proper 
recognition can be given in the discussions and decisions about the 
stoves that can have 100% avoidance of cutting wood, if that is important.

Paul

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