[Stoves] cost of stoves

Tue Dec 19 16:30:59 CST 2006

Dear ADK:

Congratulations on your agricultural exhibition and the popularity of 
the various stoves on exhibit.  You and I have both devoted a large 
fraction of what could be retirement and our expertise to helping world 
problems.  Your base expertise is agronomy and agariculture, my base is 
physical chemistry and combustion:  We seem to have "met in the 
middle":   The field of stoves, cooking, and fuels.  I particularly love 
your starch/food gas generator.
------------------------------------------------------------------------
You may remember that Robb Walt and I visited your institute in 1998 and 
demonstrated the "WoodGas" stove.  I began the development of these 
stoves when I worked at the National Renewable Energy Lab in 1986, but 
wasted 12 years trying to get good woodgas combustion with natural 
convection.  In 1997 I added forced air which gave an order of magnitude 
improvement in the efficiency, power and emissions of the stove.  The 
stove we demonstrated then was in principle the stove that we sell at 
our website, that Dean Still tested as having very low emissions, and 
the Phillips is now selling with a thermoelectric power source instead 
of batteries. 

There has recently been an explosion here in the US of imported garden 
lights with solar chargers that operate the light - or could be stoves - 
up to 12 hours on one day's charge.  I believe this will remove the 
stigma of buying batteries for our stoves.  We are also developing a 
stove with variable Gasification/Combustion air and total air which will 
burn a much wider range of fuels with even lower emissions. 

I hope you can tell me more about the Phillips stove.  My impression is 
that their thermoelectric power source will never compete with our solar 
charged batteries either in price or performance, but you have actually 
seen and demonstrated the stove, so I would appreciate your opinion on 
this.

I am puzzled by how long it has taken for people to realize the major 
advantages of forced convection in cooking with biomass fuels, and would 
appreciate your opinion.
------------------------------------------------------------------------
I know that you and many others have fought for lowest price over any 
other consideration in the development of stoves.  This may be necessary 
for the rural poor who tolerte the smoke and have "free" fuels like 
dung.  However, the urban poor are spending more and more on dwindling 
fossil fuels for cleaner cooking in the cities where smoky fires would 
make living impossible in high population density areas.  I fear that as 
propane and kerosene costs rise there will be a "triage" of billions of 
people unless we can get biomass stoves to the urban poor. 

Do you have an estimate of the ratio of urban to rural poor in India?  
In China? 
------------------------------------------------------------------------
This last year we have been focusing attention on providing 80 kW of 
power for villages along the Amazon  by gasification of Acai pits 
(produced in large quantity from the manufacture of Acai juice, high in 
antioxidants).  I have been amazed that this beautiful fuel - perfect 1 
cm spheres with a density of 1.2 - has the lowest energy content of any 
biomass residues I have encountered.  We have also used cherry pits as 
fuel, and been amazed that they have a higher energy content than any 
biomass I have encountered!  The analysis below is from our progress 
report last February to Brazil. 

    Energy Content:

The energy content of the açai pits was reported as *17.6 MJ/kg* (7566 
Btu/lb), dry basis.  Most low ash biomass has an energy content from 
*19-22* MJ/kg.  I have been looking at biomass energy contents for 30 
years and have never seen one this low, ash free basis.  Note that our 
cherry pits had an energy content of *22.4 MJ/kg (9635 Btu/lb).** *

*C*

*H*

*O*

*HHV*

Average 40 biomass

47.9

5.7

41.0

19.1

Açai pits

46.4

6.1

45.4

17.6

I have come to the conclusion that the acai are very close to being pure 
starch and fall into the category of "reproductive biomass".  They are 
approximately   C6H10O5 and so have significantly less energy than what 
I call "structural biomass" (wood, stalks, etc.).  Structural biomass 
requires lignin for strength.  (Lignin is essentially a hydrocarbon, so 
by  itself has an energy content of about 40 MJ/kg.)   

So, how come the cherry pits are higher than "structural biomass"?  I 
believe they contain vegetable oil as do many seeds in northern 
latitudes.  Seeds need energy for the next season and the energy can 
come in the form of starch - or vegetable oil. 
------------------------------------------------------------------------
One of the big advantages of the WoodGas stove is that it can burn small 
particles of biomass.  It will burn wood chips or sticks and twigs, 
widely available, but it will also burn seeds which are very dense, 
uniform sources of energy.  In the US we have cherry seeds and many 
others which which make good stove fuel.  The acai pits also burn very 
clean, but require a different air/fuel ratio.  Eucalyptus "nuts" are 
very widespread in the US and burn beautifully. 

What potential particulate fuels do you have in India that would make 
good stove fuels?
------------------------------------------------------------------------
We are now producing our WoodGas stove in India.  Would your Institute 
like to sell them there? 

Yours truly and have a great New Year,

TOM REED         THE BIOMASS ENERGY FOUNDATION      THE BIOMASS ENERGY 
CORPORATION

adkarve wrote:
> Dear stovers,
> Our Institute participated in an agricultural exhibition held recently in our city. About 100,000 visitors visited the exhibition within a span of about 5 days, and at least 10,000 found their way to our stall. We had displayed various cookstoves, ranging in price from about US$5 to US$200. The range included our own Sarai cooker, charcoal making stove, sawdust stove, Paul Anderson's Champion stove, our own pyrolysis gas stove, Philips fan stove, and our biogas unit. The maximum demand was for Philips stove, which was only kept there for display and was not for sale. However people could see that it used only wood as fuel and that it did not produce any smoke or soot.  We asked people how much they would be willing to pay for Phillips stove. The offers ranged from US$30 to 55. The prospective customers were villagers, who did not have access to bottled gas. US$ 55 is roughly the down payment that one has to make to get bottled gas. It includes the price of the LPG stove, the security deposit for one LPG cylinder and the price of one cylinder load of LPG.  This exercise shows that there is good demand for biomass burning stoves, if they guaranteed a clean burn without smoke and soot. High price is not a deterrent.
> Yours
> A.D.Karve
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