Table 1.
List over the experimental runs, feedstocks, masses, biochar yields (both as % of total mass and as % of C), biochar C, H, N contents, surface areas (SA), Cation Exchange Capacities (CEC) and PAH contents.
CEC both for unwashed (including soluble ash, i.e., both exchangeable bases and soluble cations) and washed biochar (soluble ash removed, i.e., the "real" CEC), with the difference being the apparent CEC stemming from soluble cations in the ash ("CEC ash").
Table 2.
Analyses of three biochars made in three different kilns and with two different feedstocks.
Analyzed by an EBC accredited laboratory following the EBC biochar analytical methods [4, 27] and compared to the EBC thresholds for premium and basic biochar quality.
Table 3.
Emission factors (g/kg charcoal) of CO2, CO, CH4, TSP [aerosols, from particulate matter < 10 μm (PM10)], non-methane volatile organic carbon (NMVOC), and the sum of nitrogen oxide and nitrogen dioxide (NOx), as well as the sum of all products of incomplete combustion, PIC (all gases except CO2).
Average values per flame curtain kiln type and per feedstock, and kiln literature values (traditional non-improved kilns, retort kilns with syngas circulation and combustion, TLUDs).
Fig 1.
Emission factors for CO2, CO, CH4, TSP (aerosols, derived from PM10 as described in the methods, non-methane volatile organic carbon (NMVOC), and the sum of nitrogen oxide and nitrogen dioxide (NOx), as well as the sum of all products of incomplete combustion, PIC (all C-containing gases except CO2).
Flame curtain: based on 17 runs of 10 to 15 measurements each done within the present study. Retort and non-retort kilns: average values from refs. [10, 12]. Error bars represent standard deviations in 50 to 250 individual measurements.
Table 4.
Advantages and disadvantages of various medium-size kiln types.