[Stoves] The chemistry and metachemistry of stove emissions or health (Re: Crispin)

[Crispin Pemberton-Pigott]

Dear Nikhil

‎I am reporting, not inventing. The thing is the devices people have now are so designed that they produce high CO under two common conditions: turned down with lots of fuel in, and the late fire burn when the excess air level is high. The result is that after people die, they seek explanations and one is that 'the fuel produces high CO'.

It is no different from saying 'that fuel has high PM'.

Today Altanzul from Ulaanbaatar, a Masters student at CAU, is testing a locally made version of the TJ Model 4 (on my website). She is running the Hebei Providence test sequence which is a six hr test I five distinct phases. The ignition phase and first hour are ignored because the stoves are lit one per season so emissions are irrelevant.

She told me today that basically, under those terms, the stove doesn't make any PM at all. Zero. ‎ This is the model we have 25 local producers asking for drawings.

Because of strong interest here in Bishkek, we are also making today a low pressure boiler based on the same (GTZ7.1 based) crossdraft combustor. ‎We are estimating it will deliver over 7 kW into the water. It is quite small so hopefully it will be cheap.

All three of these versions ‎are living proof that the famous 'dirty coal of Chinese industry' is nonsense. The coal is actually pretty good. Low sulfur, high volatiles (easy to light) and easy enough to break down to size. $50 per ton.

I just saw some figures Saturday showing typical fuel consumption of 4-4.5 tons per season which aligns well with Ulaanbaatar. With a fuel saving of 30%, 500,000 households and 4.5 t/p.a.‎ The savings are on the order of 675,000 tons. At $50 per ton the savings would be more than $34m.

For those interested, the CO2 reduction would be about one million tons per year.

Being inherent, ‎the CO2 is not to be avoided, but it can be reduced.

Regards
Crispin


Dear Mr Pemberton-Pigott: You must be joking. (I wish I could say, "I knew Richard Feynman. Richard Feynman was a friend of mine. And you, sir, are no Richard Feynman and may not joke around.)

Who really believes that "This is a high CO coal, that is a low CO coal."? They need an education.

Emissions depend on combustion conditions. My free lesson is that children should rot memorize it. Only when combustion conditions cannot be changed can one speak of "low CO, high CO" coal for that particular application.

I remember "low-mid-high vol" coals, reflecting the hydrocarbon content. One designs combustion chamber according to coal quality that is most economically purchased over a 30-40 year life of a furnace of, say a power plant. If coal markets change radically, one may change the furnace design and other parts of a power plant to accommodate different coal chemistry and see how one can change coal supply and transport contracts.

I do remember one instance like that in the US - around the time "acid rain" legislation came to be passed. Some "low vol" coals, from some counties in Pennsylvania and western part of Virginia, happened to be low-sulfur. These coals were also ideal for coke preparation, but the collapse of the US steel industry and softness in the coking coal (or "met coal") market meant they did not command as big a price premium as they did earlier.

It was generally believed that low-vol coals could not be used in power plants, which were generally designed for the more plentiful mid- and high-vol coals. However, some utilities - I think in Pennsylvania - started testing low-vol coals in small shares and discovered that they could use the low-vol coals without significant change in the furnace and plant design, just changing some operations in order to use a blend that also met the SO2 reduction requirements.

That is my vague recollection from around 1990-94. I worked on some "gassy" mines in many states to develop Coal Bed Methane (CBM) projects.

"Fracking" gas was not yet on the horizon then.

In short, CO is not a property of coals. Those who believe otherwise should be subjected to an RCT of their own CO intakes and performance of their brains. I can propose some metachemistry hypotheses whose tests will be subjected to meta-review by the super-human GBD folks.

Frankly, is this worth discussing? If fuel size influences combustion conditions and economics, then sure, fuel chemistry and size need to be considered together.

Or is the ISO IWA water boiling fixated on particular fuel chemistry range and fuel size?

Nikhil


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Message: 6
Date: Sat, 15 Oct 2016 13:44:37 +0000
From: Crispin Pemberton-Pigott <crispinpigott at outlook.com<mailto:crispinpigott at outlook.com>>
To: 'Stoves' <stoves at lists.bioenergylists.org<mailto:stoves at lists.bioenergylists.org>>
Subject: Re: [Stoves] A breath of fresh clean air: "Contextual Design
        and Promotion of Clean Biomass Stoves" (ESMAP - Indonesia)
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Dear Nikhil

Thanks for the compliments to the team. I appreciate that you specifically mention the context element as being an important facet of performance (not just emissions). If a fuel supply is limited to large-ish hard trees (think: rural Zimbabwe) cooks are not willing to split them into strips for feeding into a stove. And that is that. Stick-fed stoves are rejected and they go back to consuming 12-15 kg of wood per day.

That is a contextual mismatch: fuel size.

In support of preferred fuel:  I found out something interesting this week which is that the sub-40mm coal in Kyrgyzstan is quite a bit cheaper in rural areas than 80mm coal. The 80 is preferred ?because it burns longer? but that is only because they have far too much excess air so the only solution is to decrease the surface to volume ratio. In that condition ? high EA and low surface/volume ? it is not possible to burn it cleanly or completely.

Another aspect of the context is that people strongly believe that coals have  inherent gases contained in them that come out. ?This is a high CO coal, that is a low CO coal.?  That sort of thing. Obviously the stove is an important contributor to any CO produced. If we have a stove that requires a certain size of fuel (a TLUD, for example) then we are forced to change that part of the context, something that may not succeed.

In support of ignoring preferred fuel:  A success story in this regard is the Sumba Island salt maker which requires that the fuel be cut short enough to fit into the stove, not left sticking out. The effort is more, but the fuel saving is 70% so overall the effort is reduced. This provides an incentive to adopt the far more efficient evaporating system (fuel is purchased). They enthusiastically agreed the system was, on balance, much better and offered to do the additional cutting.

The context includes anything that affects the family or the performance. The CSI project was a clear, firm step in the right direction. Contextual testing can assist the early decision process about what to permit and promote. I received today two new tests from Java, numbers 457 and 458.  They are cranking them out very consistently. One of the new metrics, the heat flux (cooking power per sq cm of heater pot surface) is a reasonable predictor of acceptance or rejection by the market. One model (we don?t pick winners) was recently dropped by the vendors because people complained it was underpowered. That was obvious enough from the contextual test which showed a gap between the number people require (2.7 W/cm2) and the candidate stove (less than 2). In other words, ?we told you so?.

Now W/cm2 is not a water boiling metric is it? Well, yes it is, indirectly. If I know the heating ability, expressed on that basis, I can tell you how long it will probably take to boil any quantity of water in any size of pot in that particular stove, using only a calculator or a set of curves on a chart. Experiments showed this is true to within a minute.  This metric frees the tester from having to use a certain pot size or certain amount of water. In other words, it is a metric suited to all contexts.

In the referenced CSI Indonesia Pilot the funding is being used up as the supply channels are filled and sales continue. Apparently people like the approved stoves.  Except the one we thought was underpowered? ?

Very cool.

Regards
Crispin





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