Flame curtain pyrolysis of oil palm fronds for potential acidic soil amelioration and climate change mitigation.

In an endeavor to make biochar affordable for small-scale farmers, the flame-curtain based Kon-Tiki kiln technology was used in this study. Oil palm fronds were pyrolyzed in earth and metal Kon-Tiki kilns to produce biochar which has properties suitable for acid soil amelioration and climate change mitigation. • Both metal and earth Kon-Tiki kilns produce OPF biochars of similar quality. • Average OPF biochar yield from both kilns was 16 ± 4 wt. % with a pH of 10.02 ± 0.04. • Apparent carbon sequestration potential of Kon-Tiki OPF biochar is 0.27 ± 0.04 kg CO2 /kg OPF. • Correlation between molar H/C ratio and pyrolysis temperature of Kon-Tiki kiln has been identified. • Earth Kon-Tiki kiln is one of the most cost-effective processes for smallholders to produce OPF biochar (177 USD /t). Kon-Tiki kilns have been recommended as an easy-to-use, affordable yet environment-friendly approach to produce biochar. The flame curtain technology has been tested on a limited range of ligno-cellulosic biomass; therefore, this study explored the operation and performance of earth (EKT) and metal (MKT) Kon-Tiki kilns using abundantly available tropical oil palm frond (OPF). The apparent carbon sequestration potential (CSP) was estimated based on the H/C org ratio method. Our results demonstrated that both kilns reached highest treatment temperatures of 790 ± 100 ℃ (EKT) and 792 ± 44 ℃ (MKT) (p = 0.98) and exhibited a sinus wave-like temperature profile in the case of MKT. The average biochar yield produced from both kilns was 16 ± 4 wt. % with a fixed carbon and ash content of 56 ± 3 wt. % and 27 ± 3 wt. %, respectively. The OPF biochar had a pH of 10.02 ± 0.04 with a liming capacity of 8.91 ± 0.17 % calcium carbonate equivalent. The molar H/C and O/C ratios were 0.45 ± 0.03 and 0.19 ± 0.09, both satisfying IBI and EBC criteria for biochar. OPF biochars were mesoporous (< 50 nm) with a BET (N 2) surface area of 180–190 m²/g. OPF biochar had an average CSP of 0.27 ± 0.04 kgCO 2 /kg OPF. Biochar production cost was estimated to be 177 and 335 USD /t for EKT and MKT respectively. Our study demonstrated that OPF biochar of similar quality, quantity and CSP can be produced by both EKT and MKT. [ABSTRACT FROM AUTHOR]