[Stoves] Burning unhealthy gases improves efficiency (Re: Philip, Crispin, Paul)

[Nikhil Desai]

Philip:

Thank you for the comment, "I think the remark about “Solid fuel stoves
that cook the fuel are much cleaner, generally, than those which don't.”
has to do with the removal of the volatile fraction of the fuel, which, for
instance in bottom-lit fires, is driven off by heat as “smoke”."

I don't know why I misread it the first time; my eyes must have faced
smoke. I should have interpreted it the way you describe.

I think Paul characterized it similarly - "making and burning gases".
Except that it probably is not as much as "removing" the volatile fraction,
but giving it the right amount of air and releasing it in gaseous form so
it can burn cleaner.

About the 24MJ/kg coal you burnt -- was it high-vol to begin with and had
it been ground finely? In a way, a pulverized coal furnace in a power
plant, with exhaust gases being passed through a baghouse or an ESP to
capture the very fine particulates, does the same thing, no?

Why do you call it a "working hypothesis", I wonder? This was the coal
chemistry (and physics, due to different grinding index values) and
combustion link I learnt.
++++

Here is a conundrum -- before 2000 or so, Kirk Smith used to discuss
individual components of air emissions from "uncontrolled combustion of
 unprocessed solid fuels" and claim that exposures amounted to smoking 400
cigarettes a day. Most of these were PAHs that could be just burnt away
better (hence his qualification about "uncontrolled" and "unprocessed";
controlled combustion of either raw or processed fuels can achieve more
complete combustion, depending on design and operational factors.)

Then he took a sharp turn sometime in the mid- to late 2000s and stuck only
to "PM2.5" indiscriminately which he assumed to be equitoxic. (The only
justification advanced is that "we don't know if that is not the case",
which to me is irrational, given no causal links to disease patterns.)

Voila, "improved combustion" was out the window as a technical solution.
"Solid fuels" became "dirty by definition", LPG became "clean by
definition". "Killing by definition" followed logically, given the
Integrated Exposure Response assumption.

For centuries and all over, humanity has tinkered with flow of air,
temperature of combustion, fuel feed methods, shape and materials of stoves
and furnaces of many a size, to improve efficiency and burn off volatile
fractions (and water in some cases).

I have never known Prof. Smith to bother with metal content in solid fuels
that is ash (or solid waste of combustion) or char left unused. He
single-handed brought about a millennial intellectual revolution -- all
solid fuels are dirty per se. No use bothering with improved combustion.

I submit this theology is at the root of the SDG that sets as goal a
reduction in the % of households that use solid fuels as the primary energy
source for cooking, and generates aDALYs so Gold Standard Foundation can
collect fees by fooling the gullible.

Mere science has huge political consequences. Prof. Smith has driven a
stake in the heart of "more complete combustion" -- "More Complete Union of
Carbon and Oxygen", I used to say - that I suppose is the core mission of
this group. I support his call for transition to LPG and electric induction
stove, but I think it is still worthwhile to do better of what we know how
to do better anyway.

Volatile matter has higher heating value, and more complete combustion not
only burns off unhealthy gases but improves efficiency. If I had any
objection to Crispin's statement, it is probably just that small solid fuel
stoves for cooking are not as versatile as gas stoves, which meet user
preferences for control and time-saving and leave no ash.

I wonder if cooking some foods releases PM2.5. Prof. Smith would declare
not just that cooking kills, but food kills. (Which some do, but that is
another tale.)

Nikhil


------------------------------------------------------------------------


On Wed, Sep 6, 2017 at 6:19 AM, Philip Lloyd <plloyd at mweb.co.za> wrote:

> Nikhil, Crispin
>
>
>
> I think the remark about “Solid fuel stoves that cook the fuel are much
> cleaner, generally, than those which don't.” has to do with the removal of
> the volatile fraction of the fuel, which, for instance in bottom-lit fires,
> is driven off by heat as “smoke”.  I recall our experiments with a 24MJ/kg
> coal burned bottom-lit, and the “smoke” collected on a small electrostatic
> precipitator we built. The ESP soon clogged! The material recovered from it
> was 33MJ/kg. Pyrolysing the coal at ~400 deg C until the volatiles were
> reduced to ~8% gave a 21MJ/kg fuel that emitted <5% of the smoke that came
> off the unpyrolysed coal under the same conditions.
>
>
>
> Preheating the fuel, as happens in Crispin’s “cross-draft” stove, must
> help to release the volatiles early.  Well mixed with primary air, they
> then burn cleanly, and there is no smoke.
>
>
>
> It’s only a working hypothesis; it would be interesting to sample the
> atmosphere in the fuel bed at the bottom of the preheating zone.
>
>
>
> Philip
>
>
>
>
>
> *From:* Stoves [mailto:stoves-bounces at lists.bioenergylists.org] *On
> Behalf Of *Nikhil Desai
> *Sent:* Wednesday, September 6, 2017 4:36 AM
> *To:* Crispin Pemberton-Pigott
> *Cc:* Discussion of biomass cooking stoves
> *Subject:* Re: [Stoves] News: National Geographic on promotion of gas
> stoves over improved woodstoves - in Guatemala
>
>
>
> Crispin:
>
> I am humble, not a humbler. Of course I won't have heard of "Guidance Unto
> the Ignorant". I learnt some 25+ years ago, "You don't know more, you just
> know different things." (From a 4-year old. I celebrate her as my teacher.)
>
> Of course "pride of ownership" matters and factors into "price of
> ownership" users are willing to pay. That was the point of my "Modern
> Cooking" piece five years ago - moving away from purely "scientific"
> metrics and placing the cook in the center.
>
> I don't know how much coal is used in cookstoves; in India, limited to one
> or two states, more in rural China. I don't know about Indonesia, Colombia,
> Korea, Mongolia any longer. But I agree there is more potential in coal
> than general biomass (dung, straw, wood waste) simply because coals are
> regionally specific and can be made consistent quality by price premia for
> quality. Same can be applied to wood. All depends on how much fuel is
> self-generated (farm waste, dung) and collected.
>
> All the "cookstoves and health" literature has failed to collect any data
> on stove type (the song goes "three stone fire or other traditional
> stoves"), fuel collection (scavanging or self-produced), dwelling type or
> size/quality of ventilation. If we bothered to define the context, we would
> have a better definition of the problems than theorizing in air-conditioned
> hotel rooms.
>
> I am not yet ready to endorse your view that "Solid fuel stoves that cook
> the fuel are much cleaner, generally, than those which don't." Because
> the quality and relative cost of fuels and stoves, and user preferences,
> matter.
>
> After all, cookstoves are for cooking meals, not merely generating heat.
> The heat that matters comes from spices and conversations.
>
> Nikhil
>
>
>
> On Tue, Sep 5, 2017 at 9:35 PM, Crispin Pemberton-Pigott <
> crispinpigott at outlook.com> wrote:
>
> Dear Nikhil
>
>
>
> As paid up members of Humblers Anonymous we should carry on offering what
> we can to whoever will accept it. Have you heard of the book from the
> 1800's "Guidance Unto The ‎Ignorant"? That guy should join our club.
>
>
>
> Regarding 'cool inventions': inventors want their creations to be
> considered as cool as they think they are. Customers often have a different
> concept of what is cool.
>
>
>
> In some markets 'pride of ownership' is about what others think is cool.
> It rates highly, number 3 or 4, in ranked purchasing decision contributors.
>
>
>
> For solid fuels and generating some sort of broad revolution, I hold far
> more hope for coal burners than wood because in a large fraction of places
> where coal dominates domestic energy, there is no option, or the option is
> limited and in the process of being actively conserved. It is far easier to
> burn coal cleanly than indeterminate wood. Animal dung is quite predictable
> but requires some basic processing in many cases.
>
>
>
> For biomass, processed wood and slash holds promise but the 'exciting'
> developments are (largely) in the grip of the char-makers with their own
> agenda to which the users should bend their lives. How often does that work?
>
>
>
> If I advised the TLUD promoters I would suggest getting widespread
> adoption of the devices before trying to hornswaggle funding mechanisms for
> char buy-back ideas. If gasifiers generate twice the heat of charmakers
> from a kg of fuel‎, that is serious competition against the alternative.
>
>
>
> Solid fuel stoves that cook the fuel are much cleaner, generally, than
> those which don't. That's a fundamentally different approach and qualifies
> in my book as a shift as great as introducing kerosene.
>
>
>
> Regards
>
> Crispin
>
>
>
>
>
>
>
> Crispin:
>
> In all humility, may I suggest that your answer "Ignorance about how to
> invent cool stuff and get it adopted" comes across as a bit arrogant?
>
> Under conventional stereotype, where women are the principal home workers
> and hold exclusive responsibilities and powers over cooking and feeding (if
> not on purchase of food ingredients), I submit that cooking is about (a)
> women's time and energy allocation; and (b) the overall human environment,
> in and around the homes.
>
> There is perhaps not a single "cool" invention in solid fuel cookstoves
> does not seem to hold much promise for the Third World masses the way it
> happened with, say, Primus or Nutan stoves using kerosene some 60-80 years
> ago, or LPG/electric stoves and other thermal appliances over the last 50
> years to this date. (There are fancy wood cookstoves in the Western markets
> as well).
>
> Then again, who knows, wood or pellet stoves with electric assist may
> change a lot.
>
> I do agree there is a wide chasm between the users and the inventors, and
> the overall context of fresh and waste biomass with considerable variation
> in economic geography, that may be said to limit success with solid fuel
> stoves in the past.
>
> Remember, the current fraction of humanity, the Bottom Half, is more
> variegated structurally from the upper half than was the case 50 or 100
> years ago. And the bottom 20% if much farther apart in assets and income
> from the top 20% than ever, at least in the last 100 years.
>
> Population and human capital (health, education/skill-base, employment,
> security) dynamics are far more complicated than the simple mindsets of the
> 1960s to 1990s suggest (and which is what lies within many of us).
>
> Thank you so much for the pithy "Hence, the current mess."
>
> As GACC slides into the last three years of its plan, it's worth
> revisiting "the mess". Reformed thinking and institutional apparatus are
> necessary.
>
>
> Nikhil
>
>
>
>
>
>
>
> On Mon, Sep 4, 2017 at 11:59 AM, Crispin Pemberton-Pigott <
> crispinpigott at outlook.com> wrote:
>
> Dear Gordon
>
>
>
> - What are people trying to do?
>
>
>
> Invent cool stuff and get it adopted to help save the world.
>
>
>
> - What problems are getting in the way of your success?
>
>
>
> Ignorance about how to invent cool stuff and get it adopted.
>
>
>
> - What collaborations are possible?
>
>
>
> The best one would be for the ‘stovers’ to approach social scientists to
> find out in much clearer detail why people behave the way they do when they
> use domestic energy and apply it in their lives.
>
>
>
> There is usually a gulf between the wanna-be designers and the potential
> users, as large as the gap between marketing people and the self-same
> designers.
>
>
>
> A three-way collaboration between marketing, design/engineering and
> behavioural scientists would produce products that would naturally attract
> funding.
>
>
>
> At the moment people seek funding first, technical solutions second,
> marketing expertise third, and a deep understanding of the users last.
>
>
>
> Hence, the current mess.
>
>
>
> Regards
>
> Crispin
>
>
>
>
>
>
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