Emissions and Climate-Relevant Optical Properties of Pollutants Emitted from a Three-Stone Fire and the Berkeley-Darfur Stove Tested under Laboratory Conditions

Abstract

Cooking in the developing world generates pollutants that endanger the health of billions of people and contribute to climate change. This study quantified pollutants emitted when cooking with a three-stone fire (TSF) and the Berkeley-Darfur Stove (BDS), the latter of which encloses the fire to increase fuel efficiency. The stoves were operated at the Lawrence Berkeley National Laboratory testing facility with a narrow range of fuel feed rates to minimize performance variability. Fast (1 Hz) measurements of pollutants enabled discrimination between the stoves' emission profiles and development of woodsmoke-specific calibrations for the aethalometer (black carbon, BC) and DustTrak (fine particles, PM2.5). The BDS used 65±5% (average±95% confidence interval) of the wood consumed by the TSF and emitted 50±5% of the carbon monoxide emitted by the TSF for an equivalent cooking task, indicating its higher thermal efficiency and a modest improvement in combustion efficiency. The BDS reduced total PM2.5 by 50% but achieved only a 30% reduction in BC emissions. The BDS-emitted particles were, therefore, more sunlight-absorbing: the average single scattering albedo at 532 nm was 0.36 for the BDS and 0.47 for the TSF. Mass emissions of PM2.5 and BC varied more than emissions of CO and wood consumption over all tests, and emissions and wood consumption varied more among TSF than BDS tests. The international community and the Global Alliance for Clean Cookstoves have proposed performance targets for the highest tier of cookstoves that correspond to greater reductions in fuel consumption and PM2.5 emissions of approximately 65% and 95%, respectively, compared to baseline cooking with the TSF. Given the accompanying decrease in BC emissions for stoves that achieve this stretch goal and BC's extremely high global warming potential, the short-term climate change mitigation from avoided BC emissions could exceed that from avoided CO2 emissions.

Emission factors of health‐ and climate‐relevant pollutants measured in home during a carbon‐finance‐approved cookstove intervention in rural India

“…Intervention stove emissions had significantly lower AAE (group mean ~0.9) than those from traditional stoves (group means ranged from 1.2 to 1.3), which were not significantly different across seasons and groups. Preble et al also observed lower AAE values for another rocket stove model than for a three stone fire in laboratory testing [ Preble et al , ]; the rocket stove emissions in that study also had higher EC/PM ratios. These AAE values suggest that brown carbon likely makes a relatively small contribution to absorption for most emissions from cookstoves, and especially those from alternative stoves.…”

“…Our results suggest that rocket stoves such as that tested here are not an effective means to reduce BC emissions and mitigate climate forcing from these short‐lived species (though they may provide other benefits including fuel use reductions). Other lab [ MacCarty et al , ; Preble et al , ; Arora and Jain , ] and field [ Roden et al , ; Johnson et al , ; Kar et al , ] studies have also observed greater absolute or relative contributions from EC/BC to PM emissions from natural draft stoves, and so this finding should not be especially surprising at this point. Intervention stoves had significantly higher EC EFs, and EC contributions to PM, than traditional stoves, and thus light absorption from aerosols will be greater and the potential offsets from cooling OC lower.…”

“…Finally, EFs are important inputs to emission inventories used to estimate the larger‐scale impacts of traditional and alternative technologies on regional air quality and climate change. Numerous stove types [ Smith et al , ; Zhang et al , ; MacCarty et al , ; Jetter et al , ; Just et al , ; Arora et al , ; Preble et al , ; Arora and Jain , ] have undergone laboratory testing using standard protocols like the Water Boiling Test (WBT) [ Bailis et al , ]. Such tests are important to probe the potential of a stove and assess its relative performance under closely controlled conditions, thus serving the first purpose listed above.…”

Cookstoves illustrate the need for a comprehensive carbon market

“…Previous studies and measurement parameters used to conduct meta-analysis of emissions by cookstove type. With the exceptions of Roden (2006) [17] Johnson (2007) [53] and Preble (2014) [42] every study conducts three tests per stove. We aggregate data from all stoves of the same class: traditional, or unimproved (T), charcoal (C), natural draft (ND), forced draft (FD), and gasifier.…”

Reducing Ultrafine Particle Emissions Using Air Injection in Wood-Burning Cookstoves

“…4 Researchers have explored new environmental technologies for increasing efficiency in biomass cookstoves while decreasing harmful emissions, primarily focusing on particulate matter (PM). [5][6][7][8][9][10][11] Previous research reveals that introducing turbulence (via air injection) into the gas-phase combustion zone can dramatically improve cooking performance and reduce the total mass of PM generated from biomass combustion. 5,9,11 Injecting air into the gas-phase combustion zone to generate turbulence (here-on referred to as air injection) promotes better gaseous fuel-air mixing, leading to more complete combustion, and can increase residence time of soot in the flame, promoting oxidation of soot.…”