[Stoves] A "Cut and Paste" Summary of the 2014 WHO Guidelines

Tue Dec 2 21:07:04 CST 2014

Thanks Dean – that is very helpful.

Stovers: there are some issues really worth discussing in this document.

Levels of CO and PM higher than expected in clean fuel studies

9.)     Even allowing for variability and differing circumstances, it is clear that the measured levels of PM and CO in homes using clean fuels are much higher than predicted. This does not undermine the model, but points towards other explanations. These include continued use of the traditional stove (even in stove/fuel evaluation studies), along with the new one (known as stacking), other emission sources in and around the home (kerosene lamps, waste burning), and external sources such as fuel combustion from other homes and other sources of combustion contributing to outdoor air pollution entering all homes. (pg.123)

That is of great concern to me because if the model is not predictive, it means predictions of improvement are also not going to be reasonably accurate. It does however open up a new possibility which we are exploring at the moment in Indonesia: the use of specialised solid fuel cookers for dedicated tasks. TLUD stoves are highly suited to boiling water in a single-function device. The use of such a ‘kettle’ combined with LPG would make for a very clean combination. This should be explored as an intervention strategy that can achieve much faster results than that anticipated by ‘replace the stove and fuel’.

Model based on 75% of pollution going up the chimney

10.)  The emissions model allows for ventilation (with a flue or chimney) by assuming (based on empirical data from several studies and countries) that the fraction of total emissions entering the room lies between 1% and 50% with a mean of 25% and standard deviation of 10%. On average, therefore, it is expected that emissions entering the room from vented stoves are 75% lower than with unvented stoves. (pg.123)

Twenty five percent? This is an unreasonable assumption. Good heavens. No chimney stove operating like that would be used in any self-respecting traditional home in Mongolia or Indonesia or South Africa or Canada for that matter. No wonder the chimney stove ‘forecast’ of their model emissions into the home has such a poor result. 

Was this perhaps deliberate in order to argue that only LPG and electricity can suffice? Seriously – why would such an assumption be adopted, followed by a claim that chimney stoves ‘can’t meet the emissions requirements into the room’?  They could easily be met by using a proper chimney.  I hope this is not the beginning of a trend to misrepresent the performance of clean burning solid fuel stoves. Gasifiers burn solid fuels – anything from peat to wood to pellets. To label everything as inherently ‘dirty’ is unreasonable. Charcoal is a very clean fuel in terms of PM even in a bad stove. In a good one, the CO is really low as well.

I was already worried when I saw in several places references to ‘clean fuels’ as if the stove was not an inseparable element of clean combustion. There is no such this as a ‘clean fuel’. Any fuel can be burned badly if it is put into a crummy stove. 

As always, if a stove is tested out of context, the results are suspect. 

Regards

Crispin

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Hi All,

I've attached a "Cut and Paste" Summary of the new WHO Guidelines.

Best,

Dean

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