Overlooked emissions: Influence of environmental variables on greenhouse gas generation from woody biomass storage

Combustion of biomass for electricity production is a pathway for utilizing woody residues that would otherwise be considered waste. Woody residues are often stored in large piles prior to combustion, and greenhouse gas emissions from this storage phase are understudied and often assumed to be negligible. This study investigates the effects of three environmental factors (temperature, oxygen concentration, and moisture content) on select greenhouse gas emissions (CO2, CH4, N2O) from decomposition of woody biomass stored under conditions commonly found in biomass storage piles. Under all treatment conditions, CH4 was detected in concentrations above ambient levels, indicating that woody biomass storage conditions are conducive to anaerobic decomposition. Temperature is a key control on methane emissions: methane concentrations were significantly higher at 60 degrees C than they were at the two lower temperature treatments, 20 degrees C and 40 degrees C (Student's t-test, p < 0.0001 in both cases). The greatest concentrations of CO2 in this study were observed at 40 degrees C treatments. Temperature and moisture content had statistically significant effects on CO2 emissions (p < 0.01, p < 0.001) and oxygen concentration and moisture content had significant effects on CH4 emissions (p < 0.05 in both cases). The generation of methane under environmental conditions that mimic stored woody biomass indicates that greenhouse gas emissions from storage are not negligible, and could be a key sensitivity in the net carbon emissions from bioelectricity.

Automated summary

This study investigates the effects of temperature, oxygen concentration, and moisture content on greenhouse gas emissions during the storage phase of woody biomass. The findings suggest that woody biomass storage conditions promote anaerobic decomposition and that temperature is a key driver of methane emissions.