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

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.