Fuel sensitivity of biomass cookstove performance

•Fuel sensitivity is far lower in the two-chamber stove than in the TLUD stove.•The NO emission factor is positively related to the nitrogen content of biomass.•The PM emission factor is greater for herbaceous biomass than for woody biomass.•The two-chamber stove produces biochar with nitrogen and carbon enrichments.•By mass, 70−80% of PM produced in the two-chamber stove is smaller than 0.25 μm.