[Stoves] Between PM 2.5 and PM 10

[Julien Winter]

Hello Stovers;

The following study specifically measures nanoparticle production from
cookstoves and shows how the size of emission particulates decreases
from 3-stone to rocket to FD-TLUD stoves.

Just, B; Rogak, S; Kandlikar, M (2013) Characterization of ultrafine
particulate matter from traditional and improved biomass cookstoves.
Environmental Science & Technology  47: 3506-3512   Doi:
10.1021/Es304351P

Abstract: Biomass combustion in cookstoves has a substantial impact on
human health, affects CO2 levels in the atmosphere, and black carbon
(BC) and organic carbon (OC) affect the earth's radiative balance.
Various initiatives propose to replace traditional fires with
"improved" (nontraditional) cookstoves to offset negative local and
global effects. In this laboratory study, we compared the size,
composition, and morphology of ultrafine particulate emissions from a
"three-stone" traditional fire to those from two improved stove
designs (one "rocket", one "gasifier"). Measurement tools included a
scanning mobility particle sizer, PTFE and quartz filter samples, and
transmission electron microscopy. In the improved stoves, particulate
mass (PM) emissions factors were much lower although median particle
size was also lower: 35 and 24 nm for the rocket and gasifier,
respectively, vs 61 nm for the three-stone fire. Particles from
improved stoves formed clearly defined chain agglomerates and
independent spheres with little evidence of volatile matter and had a
higher proportion of BC to total PM, although overall BC emissions
factors were fairly uniform. The 3-fold increase in quantities of
sub-30 nm particles from improved cookstoves warrants further
consideration by health scientists, with due consideration to the
higher combustion efficiencies of improved cookstoves.


As the authors point out, there needs to be more study into
nanoparticle production under actual conditions of stove use and with
various qualities of fuels.

We don't know that much about the chemistry and human toxicology of
nanoparticles from cookstoves.   It would seem to me that this work is
urgent.  When it is done, we may find that the health risks associated
with nanoparticles from stoves is way less than nanoparticles from
gasification of municipal solid waste and other industrial settings.
A Youtube lecture on nanoparticles by Dr. Vyvyan Howard can be found
here: http://www.youtube.com/watch?v=N2s6pr0N3vg

Any health risks associated with nanoparticles will have to be
balanced against human welfare and ecological benefits of improved
cook stoves.  That is something that needs to be explained to people
(like me) involved in rural development who have to know that improved
cookstoves can be safely recommended as part a development package.

Of course, this nanoparticle business really needs sorting out,
because it could also have serious implications for any substantive
production of biochar around the world.

All the best,
Julien


-- 
Julien Winter
Cobourg, ON, CANADA