[Stoves] cost of stoves

Wed Dec 20 07:00:21 CST 2006

Dear Tom,
I am not sure that I can disclose any design features of Phillips stove, but
as a general principle I can say that an external source of electricity such
as a photovoltaic solar panel can be used in many different devices such as
a lamp or a battery charger. With a built in source of electricity, you
would need a separate source for each device.
Yours
 A.D.Karve

----- Original Message -----
From: Thomas Reed <tombreed at comcast.net>
To: Discussion of biomass cooking stoves <stoves at listserv.repp.org>
Sent: Wednesday, December 20, 2006 4:00 AM
Subject: Re: [Stoves] cost of stoves

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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