[Stoves] Benefits of advanced wood-burning stoves greater than thought

Thu Aug 10 11:15:23 CDT 2017

Paul, Crispin:

My understanding is that organic aerosols are cooling, soot is warming. The
relative proportions depend on the degree of combustion. However, the NCSU
authors speak to "PM that the emissions form over time" and what is more, "The
effects of atmospheric chemistry are extremely important to understanding
the potential air quality benefits."

The original full paper In-Use Emissions and Estimated Impacts of
Traditional, Natural- andForced-Draft Cookstoves in Rural Malawi
<http://pubs.acs.org/doi/pdfplus/10.1021/acs.est.6b05557> Roshan Wathore,
Kevin Mortimer, Andrew Grieshop DOI: 10.1021/acs.est.6b05557 Environ. Sci.
Technol. 2017, 51, 1929−1938. Supplement here
<http://pubs.acs.org/doi/suppl/10.1021/acs.est.6b05557/suppl_file/es6b05557_si_001.pdf>
. This was reported on GACC website. NCSU news Advanced Biomass Cookstoves
Provide Benefits in Field Settings, But Less than Expected from Lab Testing
<https://news.ncsu.edu/2017/01/cookstove-emissions-2017/> 19 January 2017,
same day on GACC website Advanced biomass cookstoves demonstrate
significant climate and environment benefits in real life settings, despite
showing less than expected benefits compared to lab testing
<http://cleancookstoves.org/about/news/01-19-2017-advanced-biomass-cookstoves-demonstrate-significant-climate-and-environment-benefits-in-real-life-settings-despite-showing-less-than-expected-benefits-compared-to-lab-testing.html>
 and on a UNC blog - These Clean-Burning Stoves May Help Sustainably Feed
Nations <http://science.unctv.org/content/scienceblog/clean-burning-stoves> 29
March 2017

I can only imagine they are referring to organic aerosols contributing to
ground-level ozone. I very much doubt this is a big issue, unless the
density of biomass stoves is very high. Open burning of biomass - crop and
tree wastes, forest fires, slash-and-burn agriculture - contribute far more
organic aerosols, I suspect. Tami Bond may have done an inventory estimate
or may know of some.

Still, their argument seems to be that some PM forms over time. I found a
very interesting set of pictures by Aditya Sinha, also guided by Andrew
Grieshop, at Measurement of atmospherically relevant secondary organic
aerosol from cookstove emissions
<https://cleanaircarolina.org/wp-content/uploads/2017/03/Aditya-Sinha.pdf>.
This seems to have informed the new paper this week -Primary and
Photochemically Aged Aerosol Emissions from Biomass Cookstoves: Chemical
and Physical Characterization
<http://pubs.acs.org/doi/abs/10.1021/acs.est.7b01881> Stephen Reece, Aditya
Sinha and Andrew Grieshop, Environ. Sci. Technol., Article ASAP *DOI: *
10.1021/acs.est.7b01881

This is the first time I have read "photochemically aged aerosol
emissions". The significant conclusion from this second paper as put in the
abstract is "More efficient stoves emit particles with greater net direct
specific warming than TSFs, with the difference increasing with aging. Our
results show that the properties and evolution of cookstove emissions are a
strong function of combustion efficiency and atmospheric aging."

Aha. This second paper is based on lab studies (with read oak) unlike the
first one. But the two are complementary. I don't have access to ES&T, but
I tracked down Stephen Reece's Masters Thesis
<https://repository.lib.ncsu.edu/bitstream/handle/1840.20/33669/etd.pdf> with
the same title at NCSU, and found this conclusion quite interesting - "Our
measurements of primary and aged emissions emphasize that the properties of
emissions from different stoves vary dramatically. For example, the highly
oxygenated OA from the FDGS is distinct from that typically measured for
biomass burning emissions and showed relatively minimal evolution during
aging. FDGS emissions had the highest specific mutagenicity in lab
experiments and were associated with no reduction in childhood pneumonia in
a field trial. These outcomes could be associated with the stove’s
emissions of smaller, highly oxygenated particles. Further, field
performance of cookstoves is often far worse than in lab conditions.
Additional measurements of primary and *aged emissions* should be conducted
under real-world conditions to better understand potential health and
climate benefits of these stoves. (Emphasis added.)
---------
In short, there is nothing simple about fuels and emissions from
cookstoves, and there are no "instantaneous" benefits in disease reduction
or climatic effects, local or regional. From a policy perspective, all this
scientific research is a research expedition with no definite answers at
this stage.

Corollary: Claims of protecting health or global climate are not yet ripe,
and deserve little policy consideration at this stage. When aerosols are
included, avoided tCO2e computations get fuzzy. And "health" computations
are silly and deceptive anyway.

Back in 2006, Christoph Roden et al. had written (Emission Factors and
Real-TimeOptical Properties of ParticlesEmitted from Traditional Wood
Burning Cookstoves <http://www.stenovne.dk/Roden-2006-Cookstoves.pdf> Environ.
Sci. Technol. 2006, 40, 6750-6757), "Although biofuel is an important
regional and global source of particles, it will not be possible to measure
emission quantities and properties for every region. To represent this
source in global or regional emission inventories, *the variables that
control emission factors and environmentally relevant properties, such as
EC/PM ratio and light absorption, need to be identified and quantified by
region. These include wood type, size, and quality, local practices, and
stove design; simply acquiring the appropriate fuel is insufficient.
Measurements of emission quantities and properties should be linked with
these variables and then used to produce regional emission estimates. *

Amen. This was only for climate concerns; for health concerns, local and
immediate exposures - not just lab emission rates - of the whole suite of
gaseous and particulate pollutants matter, over a long term. It will be a
long time before scientifically defensible conclusions can be developed for
the use of changed stoves upon health and climate.

Nikhil

------------------------------------------------------------------------
Nikhil Desai
(US +1) 202 568 5831
*Skype: nikhildesai888*

On Thu, Aug 10, 2017 at 5:14 AM, Crispin Pemberton-Pigott <
crispinpigott at outlook.com> wrote:

> Dear Paul
>
> I believe they are saying that advanced stoves burn more of the carbon
> which reduces BC and may leave OC. The latter is reflective and thus
> cooling.
>
> Biomass emissions are net cooling, improved stoves are moreso. I think
> ‎that is the message.
>
> Regards
> Crispin
>
>
>
> Stovers, Benefits of advanced wood-burning stoves greater than thought
> <http://onsiteenergymanager.us12.list-manage2.com/track/click?u=affe8bf6b5232eca3c2c1b325&id=37996b6a6d&e=3fd9308259>
>
> A recent study from North Carolina State University finds that advanced
> wood-burning stoves designed for use in the developing world can reduce air
> pollution more than anticipated.
>
> Article is found at:
> http://www.biomassmagazine.com/articles/14586/benefits-
> of-advanced-wood-burning-stoves-greater-than-thought
>
> But this statement seems contradictory:   (maybe an error in the short
> summary??   I wonder what the full study actually says):
>
> Advanced stoves are more efficient than traditional ones. So, for example,
> advanced stoves require less wood to boil a pot of water. However, kilogram
> of wood for kilogram of wood, advanced stoves produce PM that absorbs more
> light than PM from traditional stoves, which produce more reflective PM.
> Absorbing PM can make a large contribution to atmospheric warming, while
> reflective PM can offset it.
>
>
> Paul
>
> --
> Doc  /  Dr TLUD  /  Prof. Paul S. Anderson, PhD
> Email:  psanders at ilstu.edu
> Skype:   paultlud    Phone: +1-309-452-7072 <(309)%20452-7072>
> Website:  www.drtlud.com
>
>
>
> _______________________________________________
> Stoves mailing list
>
> to Send a Message to the list, use the email address
> stoves at lists.bioenergylists.org
>
> to UNSUBSCRIBE or Change your List Settings use the web page
> http://lists.bioenergylists.org/mailman/listinfo/stoves_
> lists.bioenergylists.org
>
> for more Biomass Cooking Stoves,  News and Information see our web site:
> http://stoves.bioenergylists.org/
>
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.bioenergylists.org/pipermail/stoves_lists.bioenergylists.org/attachments/20170810/e11a6838/attachment.html>