[Stoves] Comparison fuel consumption
Dr. Dieter Seifert
doseifert at googlemail.com
Mon Apr 17 01:22:08 CDT 2017
Dear Crispin, dear Nikhil, dear Tom,
There are some reasons why Ben Stoves produce less emissions per kg wood
burned compared to traditional Three Stone Fire: a) The grate improves
primary air supply; b) the stove shell is supported on
extensions(distance 3 cm to the floor), so that primary and secondary
air can easily enter from all sides; c) the burnt small dry sticks can
be arranged advantageously due to the combination of ash pan and grate;
d) the efficiency is high, not because air flow is restricted, but
through the position of the pot in respect to the flames and the
conduction of the flue gases by the stove shell.
Thus there will be smaller remaining emissions per cooking task than
only with the factor of the efficiency relation 0.1/0.4 = ¼. If the
emission per kg is reduced by halve, the factor will be 1/8 (i.e. the
remaining emission is only 1/8 of the Three Stone Fire for the same
task). I think that the reduction to 1/4 or less is of importance for
the health, as one of several contributions. A further great reduction
of exposure to emissions happens if cooking with retained heat (see
http://solarcooking.wikia.com/wiki/Heat-retention_cooking) is applied.
We see in Africa a growing awareness of this wonderful chance.
In Zambia I have been told that dry beans are cheap, but they are not
cooked because the charcoal is too expensive and the hours of attention
with breathing the flue gases from the brazier causes headaches
(seeEPA-600/R-00-052. GREENHOUSE GASES FROM SMALL-SCALE COMBUSTION
DEVICES IN DEVELOPING COUNTRIES: PHASE IIA Household Stoves in India.
This EPA-Report shows that charcoal was the worst in respect of
CO-emission). Both barriers can be overcome by an improved cook stove
which avoids use of traditional charcoal and through cooking with
retained heat. This will also reduce the active cooking time resp.
exposure time to a minimum. Of course only the device for cooking with
retained heat can be used in a closed room.
Use of LPG or biogas can be an option, especially for cooking tasks
which don’t need much energy. Solar cookers may be used for boiling
water, for baking etc. Thus a combination of technologies, can be the
best solution.
The design of the Ben-Stove with low temperatures of the steel sheets
(less than 400 °C) allows the use of mild steel. This enables a simple
local production of this open source technology. With the presented
picture I wanted to illustrate that with a locally produced ICS and a
“Hay Basket” for cooking with retained heat it is possible to overcome
the burdens on health and environment even in case of households with
very low income.
Kind regards,
Dieter
Am 16.04.2017 um 22:18 schrieb Crispin Pemberton-Pigott:
>
> Dear Nikhil
>
> As time has dribbled by I have noticed significant changes in the
> focus of efforts, particularly on this Stoves List, as shifted from
> testing abstractly (fixed cycles and pots and fuels like the VITA WBT)
> to examining the contextual relevance. I have just finished preparing
> a presentation on the history of stove testing that follows not the
> numbers but the metrics as contextuality became embedded in the
> consciousness of the testing community.
>
> Starting in 1983 at TATU in the Eastern Cape, Cecil Cook and I tried
> to bring what was at the time considered to by a big improvement which
> was high mass indoor stoves with a chimney. They were really
> appreciated for holding the heat and getting the smoke outside.
>
> Criticism of the high mass mud stoves came not from the users, but
> from the technos who concluded (after promoting them for years) that
> they used more fuel than the open fires they replace. Apparently then
> didn’t interview the users about what they wanted, which was clean
> indoor air and stored heat. Fuel efficiency is not on top of
> everyone’s list, as you have pointed out.
>
> When the Vesto Stove marketing survey was being conducted in the
> Johannesburg area we found that people rated fuel consumption lower
> than several other features. BTW that inch-thick survey is used as
> curriculum material at the Industrial Design School at the University
> of Johannesburg. There are many things to learn from it about ranking
> and rating and expectations.
>
> Today we hear a great deal about contextual assessment not only on the
> ground where Practical Action, for example, has always done 99% of
> their work. They produced a $0 stove for Darfur that uses half the
> fuel of a traditional fire. Recognition of the importance of
> ‘location’ is now entrenched in the ISO Standard as document 19867-2
> which is “Part 2” of the test methods. This means that even at the
> highest international level, it is recognised that the context of use
> has to be considered if a meaningful assessment is to be made.
>
> That is quite a step forward, don’t you think? It was only a dream
> three years ago, hotly attacked as impossible to conduct and not in
> line with all the work that had been poured into fixed condition,
> arbitrary test procedures.
>
> The first categorically contextual test element was the inclusion in
> 1992 in the Indian National Test of 28 different pot sizes, to be used
> depending on the firepower of the stove. The burn rate was established
> and then a pot size was assigned for use during the test.
>
> Now we have conceptually advanced approaches including the CSI Water
> Heating Test which can be applied to a particular region, province or
> demographic. The SANS 1243 Paraffin Stove Standard includes elements
> of this, recognising that particular dangers exist in low income
> households – the close proximity in cramped homes of cheap plastic
> materials that catch fire easily, for example.
>
> Tom: Thanks for your well-constructed response to Nikhil’s question.
>
> Regards
>
> Crispin
>
> *From:*Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On
> Behalf Of *Tom Miles
>
> Pick a circumstance. Apply your contextual analysis. And, show how you
> would develop a “usable stove.” You will find that there are several
> “usable stoves” to choose from, thanks to the work of people in this
> stoves community.
>
> At ETHOS 2017, Verena Brinkman, GIZ, presented a comprehensive
> framework for evaluating stoves and their use. The framework is work
> in progress and includes many individual factors such as the stove
> performance metrics you cite. It attempts to relate them to specific
> circumstances. The challenge is how to apply the contextual framework
> to making decisions about stove development and applications. In some
> areas people now have many different stoves to choose from. In more
> desperate circumstances they have only what donor agencies can offer.
> There are many usable stoves for different contexts. They can always
> be improved but the production, distribution and use is often
> compromised by other “contextual” factors outside the control of stove
> developers.
>
> We have an impressive amount of information about the people, their
> environment, cooking fuels and devices of all kinds, the emissions and
> the health impacts in their circumstances. Through their largely
> volunteer efforts and with the assistance of government and private
> resources the stoves community has improved millions of lives while
> living and working in “context”. Many improvements are made by
> collective creativity at the local level. While we may not be able to
> make direct correlations of improvements to specific diseases, any
> number of people in the stoves community can point to cases where
> health has improved, trauma has declined, and household energy
> expenditures have been reduced. Stoves volunteers have also improved
> access to potable water, food security and other health related services.
>
> Discussions at stoves gatherings are all about context and will
> continue to be as new solutions evolve. Context definition has
> improved in both metrics and complexity in the more than 50 years.
> When I first became involved we had “séances” in huts around cooks
> imagining ways to improve their circumstances. Aid workers and
> sociologists who lived in villages and barrios carefully documented
> observations over time. Eventually researchers built models of air and
> gas flows in homes. Stoves were developed and efforts were made to
> develop and improve methods for testing the performance and emissions
> of individual devices. Universities and organizations like Aprovecho
> built and tested physical models of dwellings to validate models and
> find solutions. Berkeley Air and others have developed sensors and
> data collection systems to monitor and record when stoves are in use
> and detect pollutants in different parts of the home and on family
> members in real time. The long-term monitoring of actual cooking and
> exposures is showing new opportunities and new approaches for reducing
> health risk. You will see all of this if you study the ETHOS
> presentations, ETHOS archives, archives of this list, and the
> libraries of reports and data by GACC, GIZ, FAO and collaborators, or
> engage in any of their workshops or meetings.
>
> Our work is not easy and the technical, social, and political
> challenges are significant. We can always be critical but I see
> substantial improvement, especially in the past 20 years. Let’s
> understand and build on what we have already developed.
>
> Tom
>
> *From:*Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On
> Behalf Of *Nikhil Desai
> *Sent:* Sunday, April 16, 2017 12:00 AM
> *To:* Crispin Pemberton-Pigott <crispinpigott at outlook.com
> <mailto:crispinpigott at outlook.com>>
> *Cc:* Discussion of biomass cooking stoves
> <stoves at lists.bioenergylists.org <mailto:stoves at lists.bioenergylists.org>>
> *Subject:* SPAM: Re: [Stoves] Comparison fuel consumption
>
> Crispin:
>
> Just why is "emissions per kg burned or per MJ delivered to the pot"
> relevant?
>
> What matters is exposure profiles - presence in certain concentrations
> over the course of a day or a week or a month or a year.
>
> Perhaps. In fact, there is very little we know about emission rates,
> concentrations, exposures, and disease incidence for different
> age/sex/ethnic profiles in different parts of the world.
>
> I grant "emissions per kg burned" is a better metric than average
> hourly emission rates and loads for four-hour cooking periods assumed.
> But fuel chemistry, combustion chemistry, and air chemistry of the
> cooking area, surroundings, and everywhere else the person in question
> moves around, cannot be modeled in realistic circumstances for all
> contexts.
>
> Contextual, not general, analysis helps design usable stoves. Your
> reference to higher efficiency stove with doubled emissions is
> relevant only for burning in closed areas and bad chimneys. I wonder
> how many such stoves were used. From what I recall for India, people
> abandoned high-smoke stoves, fuel savings notwithstanding.
>
> Nikhil
>
>
> ------------------------------------------------------------------------
> Nikhil Desai
>
> (India +91) 909 995 2080
> /Skype: nikhildesai888/
>
> On Sat, Apr 15, 2017 at 8:20 PM, Crispin Pemberton-Pigott
> <crispinpigott at outlook.com <mailto:crispinpigott at outlook.com>> wrote:
>
> Dear Dieter
>
> Does the Ben Stove have lower emissions per kg burned or per MJ
> delivered to the pot?
>
> I want to consider how the emissions are reduced. While one can
> say, 'because it burns less wood the emissions are proportionally
> reduced' the reality is I expect that the reduction should be much
> more than that.
>
> If it burns half the wood with half the emissions per kg then the
> emissions are 1/4. I speak here of course with reference to CO and
> PM.
>
> I have seen, on the other hand, seen stoves that saved fuel but
> doubled the emissions. I presume that is not the case with the Ben
> Stove.
>
> Thanks
>
> Crispin
>
> Dear all,
>
> Please find attached a picture for comparison of fuelwood
> consumption of traditional Three Stone Fire and Ben Stove. The
> picture illustrates the savings with ICS and cooking with retained
> heat. Of course besides the savings of fuel there are
> corresponding savings of emissions and burdens.
>
> Kind regards,
> Dieter
>
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