[Stoves] Energy loss in making high grade fuels

[Richard Stanley]

AD,
The energy required to make a typical ag residue, hollow core briquette is almost entirely bound up in labor cost. 
•The resources are free and within usually 30 minutes of the production site and transported by hand. What you collect dry is what comes out int eh form of a finished briquette once dry with notmroe than 5% losses generally.
• All gathering processing pressing and drying processes use manually operated devices which are amortised at a few cents (US) a day.  

We could assume 60 watts continuous energy output of one average briquette-maker working as either part of a 20 person or 4 to 6 person or a two person team  on any of the 25 odd types of  presses out online and in use, today.

Generally though, one worker's output including all the collection, processing materials pressing and drying elements of the production process, will fall between 15 and 30 kgs of briquette product over a full working day for this kind of wet, low pressure briquete making process

Taking conservatively, the  lower average output of product, thats about 60watts  x 8hrs / 15kgs or, 32 watts/kg. 

An average of 140 grams each,  7 briquettes per kg.

Two and a half briquettes ( 350 grams) on average,  are consummed per person per day in the average family cooking and sanitation water situation. Thats about 10 watts per person per day

average ag-residue briquette heat output is between 1 and 2 kw, depending upon blend stove etc.
Taking again the more  conservative figure, that comes out to  an output/ input ratio  of 1000/10 or,
    100 to 1. 

Kind regards,

Richard Stanley
www.legacyfound.org


 
 
On Mar 13, 2012, at 6:09 PM, Anand Karve wrote:

Dear Stovers,
Ron Larson raised the point of energy lost while charring agricultural waste in our portable charring kilns. I have since then been thinking about loss of energy in making other types of fuels too. Take for instance ethanol. I was told that the raw product of fermentation has less than 10% ethanol, which is then repeatedly distilled to bring it to 95 (rectified spirit). This is further treated to give 100% ethanol. There is also a lot of talk about biomass pellets. Compressing light biomass into pellets or briquettes also requires a lot of energy. In the case of charring, the energy required for the process of charring is provided by the biomass itself that is being charred. By subtracting the energy of the charcoal from the energy in the original biomass, one can easily calculate the loss. But in the case of the other two examples, the energy comes from external sources and it is always treated by the processor as his best guarded secret. Can anybody throw some light on the energy loss in making alcohol and biomass briquettes? How much is the net gain in Energy in these two products?
Yours
A.D.Karve

-- 
***
Dr. A.D. Karve
Trustee & Founder President, Appropriate Rural Technology Institute (ARTI)


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