[Stoves] Ulaanbaatar Air Quality

Fri Nov 8 11:34:12 CST 2013

Dear Crispin,

In a honey combed briquette there are many holes. The electric lighter has
elements in each of the holes and the briquette lights without making
smoke. I'll bring one to ETHOS and show folks a coal stove burning without
making smoke.

Great to hear your innovations!

Best,

Dean

On Fri, Nov 8, 2013 at 8:38 AM, Crispin Pemberton-Pigott <
crispinpigott at gmail.com> wrote:

> Dear Dean
>
>
>
> The situation in China is interesting because it is so diverse.
>
>
>
> >In China burning coal instead of wood was established by Mao and it
> continues today.
>
>
>
> I was surprised to find that a company was manufacturing cast iron
> downdraft stoves in Ulaanbaatar ins 1905. I think they have been burning
> coal for a very long time but I was not aware of Mao’s popularising it.
> Maybe there was a transport issue from the places with and without coal.
>
>
>
> >We looked at the honey combed briquette makers in Shengzhou, a town of
> about 800,000, and about 185 tons per day of honey combed briquettes were
> made daily and sold.
>
>
>
> There is a plant in Ulaanbaatar that can make 400,000 a day but it was
> wrapped around a Korean stove that was a TLUD that could be refuelled.
> Interesting, pretty clean but under-powered. It also relied on waste coal
> from Nalaikh mine which is clearly a limited business model.
>
>
>
> >As you point out, coal burns with very little PM once its lit. However,
> I hear that there are other types of harmful pollution made by coal, like
> heavy metals. And it smells bad.
>
>
>
> The part about the ‘metals’ is highly variable, even controversially
> promoted as part of the ‘war on coal’. Metals that evaporate (if they are
> present in the first place) are the problem and that is easy to check.
> Coals vary enormously. Some even have fluorine and arsenic, if it is in the
> groundwater. Western China has that problem. Smelling bad is totally the
> result of bad combustion. H2S is the product of incompletely burning S. A
> clean burning coal stove (which most people have never seen) doesn’t smell
> of anything at all. It just puts out water vapour and CO2, like a biomass
> stove or a natural gas stove or ethanol and so on.
>
>
>
> >Inexpensive electric lighters are sold in China to replace the starting
> with wood although it's common to see incredible amounts of smoke in the
> morning as the restaurants start up their coal cook stoves with wood.
>
>
>
> That is a *terrible* way to light coal! Wow. The smoke is unburned fuel
> so imagine how much is lost before something gets hot enough to
> spontaneously ignite! The best method is a small TLUD wood fire sitting on
> top of a bunch of small coal, all slightly nestled into a shallow trench.
> This allows the ‘side coal’ to fall onto the wood as it burns away. We will
> explore a couple of other ideas next week. Even for the TLUD’s there can be
> a lot of smoke if the ignition is not carried out well. It is always worse
> if there is a lot of secondary air with no controller.
>
>
>
> >Adding secondary air can burn up the CO and added 10% to thermal
> efficiency because the burning CO no longer escaped unburned!
>
>
>
> The problem exemplified in the chart from the TLUD I sent earlier is that
> there is no secondary air at all. It works ‘most of the time’ but not all.
> I agree the heat loss from CO is huge if the traditional stoves. The CO
> from the TLUD’s tends to concentrate on the end of pyrolysation because
> there is quite a change in the power (gas generation rate) as it finalises
> the coking process.
>
>
>
> I wonder if John Davies is still with us on this channel.  John, did you
> notice a power increase in your heating stove when the pyrolysation was
> completing?
>
>
>
> I have seen the excess air level drop to zero. On one occasion we had a
> CO(EF) of 130,00 ppm. 13% (undiluted).
>
>
>
> >Like charcoal, once lit coal burns with very little PM. For some reason,
> the theoretical ability of coal and charcoal to burn with very little PM is
> often actively ignored and rejected.
>
>
>
> With important publications like the Berkeley stove comparison
> deliberately omitting coal stoves, when millions, probably hundreds of
> millions of people rely on them, we are failing in our basic mission of
> improving people’s lives, on which people like you and many other have
> spent so much effort. Hyping negatives, especially blaming a fuel for the
> failure of the stoves that burn it, is not helpful. The health problems
> created by burning coal are largely from condensed volatiles which result
> from poor combustion conditions, bad lighting and refuelling techniques.
> High carbon, low moisture fuels require very little air supply. It is
> possible to get the best burn on a downdraft stove with excess air of 30%.
> That is amazingly low. Imagine a coal stove with an air hole entrance 1/20
> th of the size of a comparably powered Rocket stove! Until people see
> real time measurements they find it hard to accept.
>
>
>
> >Perhaps it's good to concentrate on how to accomplish the clean burning
> of wood. When we have stoves that can burn wood with very low PM we have
> added another low PM resource for solid fuel users joining coal and
> charcoal.
>
>
>
> That is fine in places with biomass to burn. Personally I favour creating
> the resource where it does not exist, but that takes decades. China is
> doing a creditably job of getting pellets and briquettes to a lot more
> people, but the overall numbers are still inadequate. It is a big
> investment of money and energy to make them, and transport limits the
> radius of impact.  Cleaning up wood fuel emissions in a stove that is
> acceptable to cooks is a big challenge. Getting it to work ‘at all’ is
> really different from getting people to buy and use them because they like
> the performance.
>
>
>
> Frans says we should worry about dioxins, furans, naphthalene, benzene,
> polycyclic aromatics and formaldehyde from biomass combustion. Right Frans?
> Others things we inhale are listed by UC Davis here<http://exposurescience.ucdavis.edu/Projects/cancer.php>
> .
>
>
>
> Good (perfect) combustion defeats (almost) all of them.
>
>
>
> Regards
>
> Crispin
>
>
>
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