[Stoves] Wood fired, two-stage gasification employed

[Crispin Pemberton-Pigott]

Dear Kevin

 

>The problem is that devious and misleading Stove Producers can quote
results for their stove that give very low apparent CO levels, by simply
increasing the dilution rate. 

 

Well the real problem is that stove builders mislead themselves. I think the
testing is up to scratch these days, but there is so much misunderstanding
that it leaks into all manner of decision making.

 

>.Recall your discussions about the general lack of meaning of some
generally accepted stove testing methods.

 

It is a lot more difficult than it first appears because we have three
significant variables: fuel, stove structures and people cooking with both.
They all vary and if testing is not reflective of these three variables,
expect unexpected results.

 

>Would your fundamental concern be addressed if the results were presented
as:

"Grams of CO, and grams of Particulate Matter, per kG of fuel burned?" (or
perhaps per MJ or BTU of energy content of the fuel?

 

g/kg burned is common with vehicles power stations because the fuel is
relatively constant. g/kg is not god for stoves because the emissions apply
only to that fuel (wood?) at that moisture content. Change either, and the
emission rate per kg is not relevant. For example how to you compare the
Mayon Turbo stove and a Jiko, the former burning rice hulls and the latter
pine charcoal briquettes? The obvious thing with a cooking stove is that
people are going to continue burning until the food is cooked. This is an
important guide. The absorbed heat (in the pot) is the important constant.
The emissions per absorbed MJ are meaningful across all fuels, moisture
contents, stoves and cooks. Once the water boils, there is something to
compare.

 

Maintaining the temperature during a simmer is also meaningful in terms of
emissions, and fuel consumption., remembering that you can't report the
'efficiency' doing that when simmering. One could be 'warming' food or
'moderate boil' and so on. The emissions can vary substantially across the
power spectrum. That is what a heterogeneous test protocol is for: to report
the performance across a realistic range on conditions.

 

>>Great paper from Philip Hopke from Clarkson Univ. Some of you will
remember him from the Bangkok roadmap conference: 

http://www.nyserda.org/publications/10_15_eval_energy_emissions_performance.
pdf

 

>>The future is small, very small!

 

>Very interesting Paper! Thanks

 

He makes aetholometers for measuring Black Carbon nanoparticles. They are
everywhere! He carries one sampler in his pocket and showed us there is BC
in the air inside the airplane. He is also famous for using a propane
soldering torch (constant fuel, same device) to show that at different
settings of the throttle, he can get a very dirty or very clean burn. That
shows the user and power setting are important parts of the emissions.

 

Regards

Crispin

 

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