Effect of Stove Technology and Combustion Conditions on Gas and Particulate Emissions from Residential Biomass Combustion

We have systematically examined the
gas and particle phase emissions
from seven wood combustion devices. Among total carbon mass emitted
(excluding CO2), CO emissions were dominant, together with
nonmethane volatile organic compounds (NMVOCs) (10–40%). Automated
devices emitted 1–3 orders of magnitude lower CH4 (0.002–0.60 g kg–1 of wood) and NMVOCs
(0.01–1 g kg–1 of wood) compared to batch-operated
devices (CH4: 0.25–2.80 g kg–1 of wood; NMVOCs: 2.5–19 g kg–1 of wood).
60–90% of the total NMVOCs were emitted in the starting phase
of batch-operated devices, except for the first load cycles. Partial-load
conditions or deviations from the normal recommended operating conditions,
such as use of wet wood/wheat pellets, oxygen rich or deficit conditions,
significantly enhanced the emissions. NMVOCs were largely dominated
by small carboxylic acids and alcohols, and furans. Despite the large
variability in NMVOCs emission strengths, the relative contribution
of different classes showed large similarities among different devices
and combustion phases. We show that specific improper operating conditions
may even for advanced technology not result in the emission reduction
of secondary organic aerosol (SOA) forming compounds and thus not
reduce the impact of wood combustion on climate and health.