[Stoves] FW: Improved cook stoves and carbon footprint

[Crispin Pemberton-Pigott]

Dear Martha

I hope I can do justice to your questions and your needs. Hmmm....

The reason I mentioned "With respect to 'GHG' " is because I want to be
clear if you were referring to gases that have potential in global warming
models to collect or add to heat in the atmosphere. Particulates are strong
absorbers of light at most frequencies (with the caveat that some are white
and some black and everything in between).

Dr Tami Bond, a member of this list, and others have tried to quantify the
contribution to the total heat produced by coal and other emissions for a
100 year period. Roughly speaking and obviously subject to correction,
particulates would add 20% to the total quantity of heat retained after 1
century. This seems to be agreed, however there is a math problem arising
from it which is the particulates put all their heat into the atmosphere in
an agreed average of 10 days. This means early on, particulates heat the air
FAR more than CO2 (for example) and enough so that 100 years later, it is
still 20% of the total.  While one can accept this in theory, in practice
the actual air temperatures don't rise enough to allow for this.

The best I can offer is that 'brown clouds over India' and particulate
emissions capture large amounts of heat in the atmosphere - so much so that
it cools and shades the ground underneath, like a thick water vapour cloud
which does the same thing.  If you were going to talk about GHGases, the
usual reason for doing so it to talk about climate change.

>I have to take particulate emissions
>into account on a couple of levels, not just in terms of warming, but
>also in terms of health. 

Very good.

The health issues of particulates could I suppose be separated from stoves,
but GHG involves both gases and particulates. That was my point.

>I'm assuming the stoves would be used inside. 

Often, not always, and often not with large (100 litre etc) stoves.

>It occurs to me that combining biomass-burning 
>stoves with superinsulated housing might be
>a very bad idea.

Coal is no better.

>...and you had a proper
>chimney, it might be fine.

In some cases like Ulaanbaatar, the outside air is worse than the inside air
because the chimneys put the emissions into the 'commons'. So...'it
depends'.

>I also need to figure out how particulate
>emissions from a Rocket Stove would compare to a conventional
>EPA-approved woodstove.

That would require that they be tested with similar fuel using a similar
protocol.  This has definitely not been happening. The Rocket Stoves are
being evaluated on a task basis (cooking something) which the EPA stoves are
tested as space heaters, though they may also cook.

Recall at the in the earliest days of testing cars, the manufacturers agreed
to be tested on the basis of CO ppm in the tailpipe. This turned out to be a
scam.  They put pollution pumps on the car to pump extra air into the
tailpipe to dilute the ppm, and viewed as a whole, the car put out more CO
than initially because the pump took energy not required before. The engine
was, of course, unchanged.

This situation persists to this day in stove testing. Be careful how the
emissions are expressed and what the fuel was.

>Thank you for the reference to ProBEC and the Tau Stove. 

The advantage of that example is that it has been made public and that it
got funded. The testing was task-based.

>is there a term to describe the type of burn chamber that I saw on
>your website for the Basintuthu baking stove? 

Good question. It is a Tsotso-type burner (from the Tsotso stove) because it
is a perforated vertical cylinder surrounded by a second, air preheating
cylinder, sealed together at the top so that all air goes out through the
top opening of the inner cylinder. All air entry at the bottom. It was
invented by David Hancock (the famous) in about 1984. It is still in
production in Zimbabwe (believe it or not) and is in the public domain.

Regards
Crispin going to Pretoria to test stoves all day with Dexter... soon to be
of Dexter's Laboratory!