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| Stoves Archive for May 2002 |
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| 102 messages, last added Tue Nov 26 17:31:37 2002 |
[Date Index][Thread Index]
Re: Temperature dilution
Andrew and all,
>Paul wrote:
> >My original statement or implied question (above) is related to the GREAT
> >difference between the tiny bit of energy needed to do the blowing and the
> >(we hope) increase in energy from better burning of the biomass.
>At 08:01 PM 5/30/02 +0100, AJH wrote in reply:
>The "Natural Draughters" would say they can burn well enough for a
>"GREAT" difference not to occur.
Paul now writes:
I hope we can hear from the "Natural Draughters" about this.
By the way, among the GASIFER people, I am primarily a "Natural" and Tom
Reed is focused on the "Force Draft" side of stoves for domestic cooking.
But concerning the small gasifier stoves that Tom and I are developing, the
impact of the Forced (fanned) air is GREAT, and the energy input to the fan
is very little. (more below on this topic.)
>Paul wrote in the earlier message:
> >An extreme case would be to have a US$ 2 small fan with many months or
> >years of useful life and a 12-volt battery that is occasionally recharged,
> >which together make it possible to burn (in a gasifier or in some other
> >stove) some form of biomass that is otherwise literally waste product to be
> >thrown away. The heat is from the biomass. We are just trying to make it
> >possible to burn the biomass by providing a small fan.
>
>Paul, I am entirely in agreement with you on this, however the USD2
>fan may not be readily available, the battery has a finite number of
>charge cycles and the recharging system is not trivial. In fact the
>*cost* of battery provisioned electricity can be phenomenal. So how
>would you measure the utility of this motive power and the full cost
>of getting it? Would a third world cookstove client be prepared to pay
>a dollar sum for the powered air supply? Would the client be happier
>forgoing the portion of fuel to raise 70g of steam per hour to do the
>same job?
Paul now adds:
I, too, had great doubts about the cost of the battery and fan. However,
on my last trip to South Africa (March) I learned more about major SA
projects (plural) to have "off grid" energy (of the 12 volt DC type from
solar PV) to something like 50,000 households in each project. With that
kind of investment in infrastructure for DC light bulbs and radios, etc.,
then there is some DC power in place for a fan in a stove.
South Africa is considered an "Economy in Transition" country, and it is
moving toward Developed World status and structure, and is not slipping
back toward Third World conditions. That means that SA does have the
desire and ability to get the small fans and DC power to significant
numbers of people who do or will have the financial ability to purchase
improved stoves (maybe gasifier stoves, maybe other stoves). (more below)
>Andrew wrote:
>I find it interesting that both Dean and Rogerio are now tending
>toward flued cookers. To my mind this makes the combustion easier to
>control and accommodate. Also the mild induced draught available from
>a chimney makes the devices inherently safer in keeping combustion
>products out of the room.
Paul adds:
Contrast the above thoughts with a (possible) alternative that is a
force-draft gasifier that burns quite cleanly, might incorporate a small
hood with vent pipe (but not a flue or chimney), and yields charcoal as a
useful by-product.
The stove-USERS will be the final decision makers about what stoves they
will accept (assuming they are offered a choice). And several designs of
improved stoves might become quite successful.
>Were Tami's chinese coal fired cookers to
>move toward the stoves Dean is now promulgating then I am sure we can
>clean up cooking with coal. Similarly it would allow a modification of
>the rocket geometry to mitigate the need for fuel metering by pushing
>the sticks forward, reducing the need to constantly tend the fire.
I look forward to hearing more about these possible variations and improvement.
Thank you, Andrew, for your knowledgeable observations.
Paul
Paul S. Anderson, Ph.D., Fulbright Prof. to Mozambique 8/99 - 7/00
Rotary University Teacher Grantee to Mozambique >10 mo of 2001-2003
Dept of Geography - Geology (Box 4400), Illinois State University
Normal, IL 61790-4400 Voice: 309-438-7360; FAX: 309-438-5310
E-mail: psanders@ilstu.edu - Internet items: www.ilstu.edu/~psanders
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