In-Field Emission Measurements from Biogas and Liquified Petroleum Gas (LPG) Stoves

Abstract

Household air pollution from solid fuel cooking causes millions of deaths each year and contributes to climate change. These emissions can be reduced if households transition to cleaner cooking fuels such as LPG or biogas, yet emission measurements during actual use are limited. Six LPG and 57 biogas cooking event emissions were measured during typical cooking practices in Nepal. Emission factors are reported for elemental carbon (EC), organic carbon (OC), particulate matter (PM 2.5 ), and carbon monoxide (CO) and compared to measurements from wood stoves in the same households. Biogas cooking emission factors were 7.4 ± 10.9 mg MJ −1 for PM 2.5 and 0.2 ± 0.3 mg MJ −1 for EC on a fuel energy basis, and were not significantly different from LPG stoves (9.5 ± 6.8 mg MJ −1 for PM 2.5 and 0.3 ± 0.3 mg MJ −1 for EC, p > 0.05). Wood stoves emitted 50 times more PM 2.5 than biogas on a fuel energy basis and 230 times more EC. EC emissions were about 3% of total particle emissions from biogas and LPG stoves. Most PM 2.5 emissions from gas stoves were attributed to food frying and stove ignition (90%), not the gas fuel (10%), implying that there is a limit to emission reductions that can be achieved with improved fuels.Atmosphere 2019, 10, 729 2 of 15 households [10]. Electricity access requires large infrastructure development and often, in rural or developing regions, has not provided sufficient power levels or reliability required for cooking. Nonetheless, these clean fuels are rapidly penetrating into cooking markets.Biogas is a less common cooking fuel and is a mixture of gases produced from anaerobic digestion of carbonaceous material, such as brush, leaves, dung, and agricultural waste, which are also commonly directly combusted as solid fuels for cooking. Biogas digester feedstocks are generated or collected freely by many rural households, so systems generally have low operating costs and are not reliant on distribution networks beyond the household or community, yet upfront installation costs can be prohibitively high for many households.Biogas has global use for household cooking, and has been promoted by governments and NGOs for decades. In India, 0.4% of households use biogas as a primary fuel (about one million households), and many more likely use it a as secondary fuel [11]. There is evidence that biogas systems exhibit a high level of sustained use, unlike many improved biomass household cooking technologies in South Asia [12]. Digesters that are over 15 years old can be found in and around Kathmandu valley.Laboratory-based measurements of biogas stoves suggest pollutant emissions are low and similar to LPG [13,14]; however, no field-based assessments exist to confirm whether biogas in actual homes exhibit similar levels of performance, and field measurements of LPG emissions are also rare, consisting of only a few water boiling tests [13][14][15]. Field emission measurements include factors that are not typically tested in current laboratory methods, including user variability, fuel variability, and emis...

In-Home Emissions Performance of Cookstoves in Asia and Africa

“…Results from a laboratory study by Shen et al [29] reported an LPG PM 2.5 emission rate range of <0.11 to 0.61 mg/min, which is in line with the majority of the LPG events measured here emitting less that 1.1 mg/min. A recent field study by Weyant et al [30] reported similarly low emission rates from biogas and LPG (0.6 ± 0.8 mg/min), including cooking emissions, which were near the study's median limit of detection (0.8 mg/min). Combined, these results reinforce that LPG and likely other gas fuels can reduce emissions to health-protective levels, though care should still be taken to ensure that the stoves are operating as intended and displacing the traditional technologies to maximize household air pollution reductions.…”

Fuel Aromaticity Promotes Low-Temperature Nucleation Processes of Elemental Carbon from Biomass and Coal Combustion

“…Habib et al (2008) found an emission factor of 0.008 g/kg, Venkataraman (2005) found 0.01 g/kg, Shen et al. (2018) found 0.009 ± 0.005 g/kg EFs EC = 0.009 ± 0.005 g/kg, and Weyant et al found 0.014 ± 0.012 g/kg for EC. − It is easy to find that EC emission factors in biomass and coal are two orders of magnitude higher than those from LPG sources. We must also recognize that the combustion processes are different for different fuel types; hence, it may not be appropriate to directly compare the fuel mass-based EFs of the EC.…”

Modeling approaches and performance for estimating personal exposure to household air pollution: A case study in Kenya

“…Our estimated LoD for PM 2.5 emission rates was approximately 5 mg/min, which was greater than what we measured for LPG. We therefore have used the PM 2.5 emission rates for LPG reported by Weyant et al 41 and Johnson et al, 19 who were able to measure them in the field. Overall, the emission performance and pollutant concentrations were highly variable, ranging from very clean (LPG) to highly polluting (wood stoves), with charcoal in between.…”