Utilization of spiked pepper (Piper aduncum L.) as feedstock for gasification.
The massive spread and growth of invasive alien plant species (IAPS) such as Piper aduncum L. (PA) endanger the natural ecosystem. Utilizing their woody biomass as feedstock through gasification to produce renewable energy can reduce risk and provide better incentives to rural communities. Heating value (HV), fixed carbon (FC), volatile combustible matter (VCM), and ash content were used to compare PA with five other tree species - namely, Calliandra calothyrsus L. (CC), Gliricidium sepium L. (GS), Broussonetia papyrifera L. (BP), Eucalyptus marginata L. (EM), and Eucalyptus urophylla L. (EU) - as fuel for gasification. The effects of particle size (ps), air volumetric flow rate (υair), and carbonization and their interactions to cold gas efficiency (CGE), producer gas flow rate (υsyngas), and specific gasification rate (SGR) were also studied. The economics and environmental impact of spiked pepper as feedstock were evaluated by hypothetically putting up a 100 kWe gasification plant in the Upper Bauyan Watershed serving 138 households. With an electrical efficiency of 17.1%, the plant would need 990 tons of PA. Feedstock supply would be adequate even after 20 yr of operation since biomass growth rate would be faster than consumption rate. The computed carbon dioxide (CO2) emissions annually for harvesting was 9.72 tons (shelterwood method) - 781.11 tons for gasification and electrical production against direct combustion, which theoretically emits 1,729.73 tons annually. Financial analysis indicated a profitable investment with a positive net present value of PHP 6,240,257.08 or USD 122,358 (USD 1 = PHP 51), IRR of 12%, payback period of 6.97 yr, and levelized cost of electricity (LCOE) of PHP 8.90 (USD 0.17). Overall, the study indicates the economic feasibility and ecological soundness of utilizing PA as feedstock provided that silvicultural management is applied in replanting indigenous trees in eradicated lands. This method can also be effective in restoring the landscape of affected watersheds.