Recycling of Trees Planted for Phytostabilization to Solid Fuel: Parametric Optimization Using the Response Surface Methodology and Genetic Algorithm

Jibril Abdulsalam; Ramadimetja Lizah Setsepu; Abiodun Ismail Lawal; Moshood Onifade; Samson Oluwaseyi Bada

doi:10.1021/acsomega.2c06272

Recycling of Trees Planted for Phytostabilization to Solid Fuel: Parametric Optimization Using the Response Surface Methodology and Genetic Algorithm

ACS Omega. 2023 Feb 16;8(8):7448-7458. doi: 10.1021/acsomega.2c06272. eCollection 2023 Feb 28.

Authors

Jibril Abdulsalam¹, Ramadimetja Lizah Setsepu¹, Abiodun Ismail Lawal^{2

3}, Moshood Onifade⁴, Samson Oluwaseyi Bada¹

Affiliations

¹ DSI/NRF Clean Coal Technology Research Group, School of Chemical and Metallurgical Engineering, Faculty of Engineering and the Built Environment, University of the Witwatersrand, WITS, Johannesburg 2050, South Africa.
² Department of Energy Resources Engineering, Inha University, Yong-Hyun Dong, Nam Ku, Incheon 402-751, Korea.
³ Department of Mining Engineering, Federal University of Technology, Akure 340110, Nigeria.
⁴ Department of Civil and Mining Engineering, University of Namibia, Windhoek 13301, Namibia.

Abstract

Biomass resources are gaining attention to address environmental issues, ensure energy efficiency, and ensure long-term fuel sustainability. The use of biomass in its raw form is known to present a number of issues, including high shipping, storage, and handling costs. Hydrothermal carbonization (HTC), for example, can increase the physiochemical properties of biomass by converting it into a more carbonaceous solid hydrochar with enhanced physicochemical properties. This study investigated the optimum process conditions for the HTC of woody biomass (Searsia lancea). HTC was carried out at varying reaction temperatures (200-280 °C) and hold times (30-90 min). The response surface methodology (RSM) and genetic algorithm (GA) were used to optimize the process conditions. RSM proposed an optimum mass yield (MY) and calorific value (CV) of 56.5% and 25.8 MJ/kg at a 220 °C reaction temperature and 90 min of hold time. The GA proposed an MY and a CV of 47% and 26.7 MJ/kg, respectively, at 238 °C and 80 min. This study revealed a decrease in the hydrogen/carbon (28.6 and 35.1%) and oxygen/carbon (20 and 21.7%) ratios, indicating the coalification of the RSM- and GA-optimized hydrochars, respectively. By blending the optimized hydrochars with coal discard, the CV of the coal was increased by about 15.42 and 23.12% for RSM- and GA-optimized hydrochar blends, respectively, making them viable as an energy alternative.