[Stoves] News (CCF 2017): Blame the rural poor for Delhi's ills

[Crispin Pemberton-Pigott]

Dear Nikhil

>Setting "international standards" for PM2.5 in mg per MJd is a waste of time. .
Here we disagree. Again. I found this metric to be useful for setting procurement requirements for the Ulaanbaatar City Clean Air Project (UB-CAP) because it can be related to a proportional decrease in emissions from small domestic stoves eligible for a subsidy. The baseline performance replicating a typical ignition and refueling sequence was 680 mg/MJ delivered into the home.  The project was planning initially (2007) to require any stove to reduce this by 30% with a funding of $15m available.
Initial testing of candidate stoves was depressing. The majority of ‘improved stoves’ merely increased the thermal efficiency by a small amount, but the combustion was no better, sometimes worse (as much as double the emissions). Clearly we needed to shift gears on the technology employed.
For some time we tried downdraft stoves which were dramatically cleaner – certainly in the 90% range or better. A singular advantage of the DD stoves was they could burn the crummy ‘semi-coke’ briquettes that everyone kept throwing at the problem. Emissions from these SCB’s in a traditional were frequently worse (up to 35%) than the traditional stove burning raw coal because they were so difficult to ignite and refuel.
With the appearance of TLUD stoves available in bulk, things changed. There was no need to develop local production capacity in the short term but we needed a performance target suited to the task at hand, which was a reduction in total emissions. The fuel consumption metric was previously thought to be appropriate because it was assumed (incorrectly) that the emissions were inherent to the fuel – many people taught this as catechism, particularly the Europeans. The appropriate metric was mg PM2.5/MJ delivered into the home. This considered thermal efficiency and emissions per unit mass burned in a single number.
The target was set at an 80% reduction, far above the initial 30% target. The emission target set was 140 mg/MJ using a contextual test sequence based on observed behaviour. After one year it became clear from testing at the local lab that 90% could easily be achieved, meeting what was then Kirk Smith’s universal reduction target necessary to provide a “significant public health benefit”. The following year the requirement was raised to 90% with <70 mg/MJ the magic number.
The development of stoves assessed on this basis continued locally with the GTZ7.1 crossdraft and two of the Turkish “Silver” TLUD’s achieving consistent performance below 1.0 mg/MJ. When Kirk wrote a report a couple of years ago to the Minister of the Environment saying that only a new miracle technology that might achieve a 95% reduction could briefly stem the rise in pollution, the stoves already being supported were reducing 98% or better and the city air quality had improved up to 65% (depending on where you lived). In spite of consistent, multiple proofs through the years 2011-2017 that the cleanest burning of all stoves used raw coal, Kirk and others are still trying to sell the line that only a total ban on burning raw coal can clean up the air.
In the Hebei Clean Air Project, the target is <40 mg/MJNET and we had no problem finding stoves to meet that target, all produced within the province. I have recently seen a stove designed in Langfang that will consistently be under 1.0 mg/MJ, I am sure of it.
Within 5 years I predict that the project (if not national) requirement will be <5 mg/MJ which is less than a tenth of the forthcoming EPA target for 2021 for heating stoves. This will represent, for Ulaanbaatar and Chinese cities, a reduction of something >99% and this can be achieved without changing the fuel. As you can imagine, this creates some hand-wringing in certain quarters among those who had their eye on large subsidies for their favourite toys. Some people’s worst nightmare is a super-clean coal or biomass-burning stove. Odd, isn’t it?
I believe the metric mg/MJ delivered is an appropriate performance metric, assuming all the stove functions required by users can be maintained.

Regards

Crispin

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