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Microalgal biomass is the most promising and attractive alternative to replace the terrestrial crop utilization for renewable biomass fuel feedstock. The potential for biomass fuel is due to its fast growth rate and high ability for CO 2 fixation as compared to terrestrial vegetation. There are many species in the globe, growing both in marine and freshwater. In this work, the marine microalgae Nannochloropsis oculata (N. oculata) had been investigated in terms of potential abundance and physicochemical properties, which determine its feasibility as biomass fuel feedstock. The chemical composition was evaluated by energy-dispersive X-ray spectrometry, and the proximate analysis was done by performing experiments in the thermal gravimetric analyzer. During 7 days of cultivation, the average rate of increase in algal biomass was about 1.5 9 10 6 cells/ml/day. The proximate analysis of N. oculata indicated that it had compositions of low moisture content and fixed carbon, whereas high volatile matter and ash content, i.e., 3.99, 8.08, 67.45, and 24.47 %, respectively. The energy content, which was calculated through the proximate analysis results, was 16.80 MJ/kg. The algal biomass and its residue after 1,200°C were characterized by Fourier transform infrared spectroscopy to investigate their chemical macromolecular compounds. This present study concludes that N. oculata is feasible as biomass fuel feedstock, either to direct or co-combustion mode by giving special attention to high ash content.

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The thermal behavior of Nannochloropsis oculata combustion in air atmosphere were investigated by performing experiments on STA PT1600 Thermal Analyzer at heating rates of 10°C/min, 40°C/min and 70°C/min and range of temperatures from room temperature to 1200°C. The kinetic parameters were evaluated by using Kissinger and Ozawa methods. The result showed that Nannochloropsis oculata combustion occurred in five stages. Started with initial devolatilization, the main thermal decomposition and combustion process, transition stage, the combustion of char and the last stage was the slow burning reaction of residual char. In line with increasing heating rate, the mass loss rate increased as well, but it delayed the thermal decomposition processes toward higher temperatures. The average activation energy at the main thermal decomposition stage and the stage of char combustion were approximately 251 kJ/mol and 178 kJ/mol, respectively.