Emissions of carbon monoxide and carbon dioxide from uncompressed and pelletized biomass fuel burning in typical household stoves in China

Carbon dioxide (CO2) and carbon monoxide (CO) impact climate change and human health. The uncertainties in emissions inventories of CO2 and CO are primarily due to the large variation in measured emissions factors (EFs), especially to the lack of EFs from developing countries. China's goals of reducing CO2 emissions require a maximum utilization of biomass fuels. Pelletized biomass fuels are well suited for the residential biomass market, providing possibilities of more automated and optimized systems with higher modified combustion efficiency (MCE) and less products from incomplete combustion. However, EFs of CO2 and CO from pellet biomass fuels are seldom reported, and a comparison to conventional uncompressed biomass fuels has never been conducted. Therefore, the objectives of this study were to experimentally determine the CO2 and CO EFs from uncompressed biomass (i.e., firewood and crop residues) and biomass pellets (i.e., pine wood pellet and corn straw pellet) under real residential applications and to compare the influences of fuel properties and combustion conditions on CO2 and CO emissions from the two types of biomass fuels. For the uncompressed biomass examples, the CO2 and CO EFs were 1649.4 ± 35.2 g kg−1 and 47.8 ± 8.9 g kg−1, respectively, for firewood and 1503.2 ± 148.5 g kg−1 and 52.0 ± 14.2 g kg−1, respectively, for crop residues. For the pellet biomass fuel examples, the CO2 and CO EFs were 1708.0 ± 3.8 g kg−1 and 4.4 ± 2.4 g kg−1, respectively, for pellet pine and 1552.1 ± 16.3 g kg−1 and 17.9 ± 10.2 g kg−1, respectively, for pellet corn. In rural China areas during 2007, firewood and crop residue burning produced 721.7 and 23.4 million tons of CO2 and CO, respectively.

► Emission factors of CO2 and CO for uncompressed and pelletized biomass fuels.
► CO2 and CO emissions reduced by pellet fuels compared with uncompressed biomass.
► Inventory on CO2 and CO emissions from biomass burning in China rural areas.