[Stoves] ***SPAM*** Re: Risk of CO poisoning with TLUDs

[Crispin Pemberton-Pigott]

Dear Julien

The statement is false because it involves two systems of action. The char, whether in a stove or dumped out, is one system of action and produces at least some CO at some rate.

“Safe” can only be described in terms of a given environment which in this context could be a kitchen. The char emitting CO is a system nested within the kitchen system. Char cannot have the attribute “safe” in this context and attributing “safety” to char is a synecdoche.

The kitchen could be “safe to occupy” because of the combination of emission rate, volume, air change rate and physical location of an occupant. One can say the occupant is being “exposed” but exposure does not guarantee inhalation because CO being light, may rise to the ceiling and be inaccessible.

If safe is defined as an air concentration near the occupant, one can claim it is safe. However that is not something one can say about the char.

There is a technical report coming from Working Group 1 (of ISO TC 285) which discusses this concept specifically. It is also discussed in the work of WG 4. One cannot say a stove is, by itself, safe unless the context of the kitchen is also considered. The kitchen is nested within a home, usually, and the home within a neighbourhood and so on.

The nested systems discussion is an attempt to show  how to describe risks and benefits appropriately. Like the char CO, people were attributing to a fuel something related to the kitchen, or to the stove as described above.

This is most relevant when discussing the strange manner in which fuels are classified as “clean” or “dirty”. Fuels don’t have such attributes. The device consuming the fuel produces emissions (or not). To find out if using a fuel produces emissions the product has to be tested burning it.

The residual char is nested within a smouldering pile which is nested in a kitchen in a house. So, define “safe”.  Is it based on inhaled mass? Exposure time? Concentration? Emission rate? Total mass emitted?

Opinions differ.

Have fun
Crispin
________________________________
From: Stoves <stoves-bounces at lists.bioenergylists.org> on behalf of Julien Winter <winter.julien at gmail.com>
Sent: Thursday, September 21, 2023 4:51:39 AM
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
Subject: Re: [Stoves] Risk of CO poisoning with TLUDs

Hi All;

A scientist would say that the statement "all TLUDs have safe emissions of CO from residual char" is a hypothesis in need of experimental falsification.  CO should be measured under a variety of conditions (fuels, fuel moisture, primary air rates, etc) to see if the hypothesis is false.  If we can't falsify the hypothesis then we conclude that the hypothesis is "probably" true.  If we do find circumstances where CO emissions are hazardous, then we say the TLUD is "probably" safe under these conditions, but not safe under these other conditions.

Scientists are professional skeptics and engineers are professional can-do optimists, so they differ in their training and approach to research.

Cheers,
Julien

On Tue, Sep 19, 2023 at 4:13 PM Julien Winter <winter.julien at gmail.com<mailto:winter.julien at gmail.com>> wrote:
Dear Crispin;

Thanks for your detailed reply.

From this I would assume that under almost all circumstances, the TLUD is operated with sufficient ventilation to prevent dangerous levels of CO.  Nobody operates a TLUD in an enclosed space, because during flame out, there is often a small amount of smoke released that would be unpleasant if it was not dissipated.  Start-ups can also release some smoke.  I have not heard of anyone suffering "death by TLUD."

Sincerely,
Julien.

On Tue, Sep 19, 2023 at 10:04 AM Julien Winter <winter.julien at gmail.com<mailto:winter.julien at gmail.com>> wrote:
Hi All;

I should mention that I am most concerned with the potential risk when char is not handled efficiently, such as char leaving the TLUD unattended after running the TLUD with the primary air turned down, or dumping the char into a pile without quenching it.

Cheers,
Julien

On Mon, Sep 18, 2023 at 9:36 PM Julien Winter <winter.julien at gmail.com<mailto:winter.julien at gmail.com>> wrote:
Hi All;

Something just occurred to me.  If a large amount of char is allowed to accumulate at the bottom of a TLUD, and the primary air flow is low, is there a risk of carbon monoxide poisoning?

Cheers,
Julien

--
Julien Winter
Cobourg, ON, CANADA


--
Julien Winter
Cobourg, ON, CANADA


--
Julien Winter
Cobourg, ON, CANADA


--
Julien Winter
Cobourg, ON, CANADA
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