• Energy Research

Abstract High-potential biomass residues from the palm oil industry such as palm kernel shells and empty fruit bunch (EFB) must be utilized with the appropriate technology to optimize its economic benefit and minimize the environmental impacts. In this study, the cofiring behavior of hydrothermally treated EFB (HT-EFB) with coal is analyzed in terms of thermal behavior including temperature distribution and the composition of gases produced (CO and CO 2 ) through computational fluid dynamics. Several HT-EFB mass fractions are evaluated, i.e., 0%, 10%, 25%, and 50%. To complement this research, an experimental study is conducted to validate the simulation results. In general, an HT-EFB mass fraction in the range of 10–25% seems to be the most preferable cofiring condition. In addition, an integrated system is also proposed and evaluated including coal drying, HT treatment of EFB, cofiring, and power generation. Very low energy consumption during coal drying and HT treatment of EFB can be achieved. Finally, the net power generation efficiency of the proposed integrated system is approximately 40% including coal drying and HT treatment of EFB processes.

Abstract High-potential biomass residues from the palm oil industry such as palm kernel shells and empty fruit bunch (EFB) must be utilized with the appropriate technology to optimize its economic benefit and minimize the environmental impacts. In this study, the cofiring behavior of hydrothermally treated EFB (HT-EFB) with coal is analyzed in terms of thermal behavior including temperature distribution and the composition of gases produced (CO and CO 2 ) through computational fluid dynamics. Several HT-EFB mass fractions are evaluated, i.e., 0%, 10%, 25%, and 50%. To complement this research, an experimental study is conducted to validate the simulation results. In general, an HT-EFB mass fraction in the range of 10–25% seems to be the most preferable cofiring condition. In addition, an integrated system is also proposed and evaluated including coal drying, HT treatment of EFB, cofiring, and power generation. Very low energy consumption during coal drying and HT treatment of EFB can be achieved. Finally, the net power generation efficiency of the proposed integrated system is approximately 40% including coal drying and HT treatment of EFB processes.

Abstract Ammonia (NH3) has attracted much attention as both a fuel and an energy carrier due to its flexibility and overall cleanliness. As hydrogen storage, it can be used for short to long terms and has lower environmental impacts at the point of use·NH3 synthesis is commonly performed by reacting hydrogen and nitrogen via the Haber-Bosch process. Due to its energy-intensive processes for hydrogen production, as well as high pressure required for NH3 synthesis, an alternative highly efficient system is needed. An integrated system that combines biomass pre-treatment (evaporation and carbonization), combustion, thermochemical cycle for NH3 synthesis, and power generation is proposed in this work. By performing NH3 synthesis via the thermochemical cycle consisting of reduction and oxidation, the process can bypass the steam reforming process of hydrogen production. Additionally, the thermochemical cycle can be performed under an atmospheric condition in the absence of a catalyst. The integrated system is proposed based on enhanced process integration involving exergy elevation and exergy recovery. Furthermore, the effect of thermochemical cycle conditions on the NH3 production efficiency and performance of power generation at different parameters are evaluated. As a result, utilization of 100 t h−1 of empty fruit bunch can coproduce NH3 and power of 8.95 t h−1 and 46.35 MW, respectively. Besides, the developed system can achieve a total net efficiency of about 48%.

Abstract Ammonia (NH3) has attracted much attention as both a fuel and an energy carrier due to its flexibility and overall cleanliness. As hydrogen storage, it can be used for short to long terms and has lower environmental impacts at the point of use·NH3 synthesis is commonly performed by reacting hydrogen and nitrogen via the Haber-Bosch process. Due to its energy-intensive processes for hydrogen production, as well as high pressure required for NH3 synthesis, an alternative highly efficient system is needed. An integrated system that combines biomass pre-treatment (evaporation and carbonization), combustion, thermochemical cycle for NH3 synthesis, and power generation is proposed in this work. By performing NH3 synthesis via the thermochemical cycle consisting of reduction and oxidation, the process can bypass the steam reforming process of hydrogen production. Additionally, the thermochemical cycle can be performed under an atmospheric condition in the absence of a catalyst. The integrated system is proposed based on enhanced process integration involving exergy elevation and exergy recovery. Furthermore, the effect of thermochemical cycle conditions on the NH3 production efficiency and performance of power generation at different parameters are evaluated. As a result, utilization of 100 t h−1 of empty fruit bunch can coproduce NH3 and power of 8.95 t h−1 and 46.35 MW, respectively. Besides, the developed system can achieve a total net efficiency of about 48%.

AbstractBiomass serves as an alternative energy solution for decarbonizing coal-fired power plants, which have been reactivated in several countries due to the global energy crisis. Oil palm waste, owing to its abundant availability, holds significant potential as a biomass fuel. This study aimed to investigate the combustion performance of various oil palm wastes in comparison to coal. Biomass combustion is associated with ash-related problems such as slagging, fouling, and corrosion, which may accelerate ash deposit acceleration, reduce heat transfer, and damage refractory equipment in boilers. Ash-related problems were evaluated using the method commonly adopted for solid fuel, including experimental drop tube furnace combustion and ash observation. The results indicate that each oil palm waste has different combustion characteristics. Palm leaves, empty fruit bunch, and palm fronds with clean probe observation have a relatively low tendency of slagging and fouling and can be recommended as biomass fuel for co-firing. However, their high alkali and iron contents need to be considered. Palm fiber has similar combustion characteristics to coal, but it has a high slagging and fouling tendencies. The palm stems with high chlorine content have a high corrosion tendency confirmed by probe observation, scanning electron microscopy, and X-ray diffraction analyses.

AbstractBiomass serves as an alternative energy solution for decarbonizing coal-fired power plants, which have been reactivated in several countries due to the global energy crisis. Oil palm waste, owing to its abundant availability, holds significant potential as a biomass fuel. This study aimed to investigate the combustion performance of various oil palm wastes in comparison to coal. Biomass combustion is associated with ash-related problems such as slagging, fouling, and corrosion, which may accelerate ash deposit acceleration, reduce heat transfer, and damage refractory equipment in boilers. Ash-related problems were evaluated using the method commonly adopted for solid fuel, including experimental drop tube furnace combustion and ash observation. The results indicate that each oil palm waste has different combustion characteristics. Palm leaves, empty fruit bunch, and palm fronds with clean probe observation have a relatively low tendency of slagging and fouling and can be recommended as biomass fuel for co-firing. However, their high alkali and iron contents need to be considered. Palm fiber has similar combustion characteristics to coal, but it has a high slagging and fouling tendencies. The palm stems with high chlorine content have a high corrosion tendency confirmed by probe observation, scanning electron microscopy, and X-ray diffraction analyses.

Abstract In this study, we design and evaluate a highly efficient energy system for performing an integrated conversion of empty fruit bunches (EFB) to H2 that is stored in the form of ammonia (NH3). The biomass undergoes processes that include supercritical water gasification (SCWG) for H2 production and H2 chemical storage using the Haber-Bosch process to produce NH3. Exergy recovery by heat integration is employed to increase the efficiency of the system. First, EFBs are gasified with steam in the SCWG process to produce H2-rich syngas and to completely remove the pre-drying requirement. Subsequently, a syngas chemical looping (SCL) process involving three reactors is used to produce H2 that is subsequently converted to NH3 by the Haber-Bosch process. Theoretically, the integrated process can achieve a high EFB-to-NH3 conversion efficiency that exceeds 15% with a H2 conversion efficiency of 76.2% and an overall maximum syngas-to-H2 conversion efficiency of 46.3% with 100% CO2 capture capability. Compared to traditional EFB conversion processes, this process can theoretically achieve higher efficiency, and it can improve waste utilization in palm oil processing plants by incorporating exergy recovery and heat integration into the system.

Abstract In this study, we design and evaluate a highly efficient energy system for performing an integrated conversion of empty fruit bunches (EFB) to H2 that is stored in the form of ammonia (NH3). The biomass undergoes processes that include supercritical water gasification (SCWG) for H2 production and H2 chemical storage using the Haber-Bosch process to produce NH3. Exergy recovery by heat integration is employed to increase the efficiency of the system. First, EFBs are gasified with steam in the SCWG process to produce H2-rich syngas and to completely remove the pre-drying requirement. Subsequently, a syngas chemical looping (SCL) process involving three reactors is used to produce H2 that is subsequently converted to NH3 by the Haber-Bosch process. Theoretically, the integrated process can achieve a high EFB-to-NH3 conversion efficiency that exceeds 15% with a H2 conversion efficiency of 76.2% and an overall maximum syngas-to-H2 conversion efficiency of 46.3% with 100% CO2 capture capability. Compared to traditional EFB conversion processes, this process can theoretically achieve higher efficiency, and it can improve waste utilization in palm oil processing plants by incorporating exergy recovery and heat integration into the system.

Abstract Energy recovery from black liquor can be performed through gasification process at temperatures above the melting point of the inorganic chemicals. Complementing the experimental research, this study was conducted in Aspen Plus software to simulate thermodinamic modeling of detail process for gasification and combined cycle in an integrated system power plant. Mass and energy balances were examined to quantify process performance. The unrecoverable energy in a single process will be utilized in other processes. The combination of these technologies is expected minimizing the total exergy destruction the throughout system. Kraft black liquor was used as sample during process calculation. The proposed integrated-system shows a high energy efficiency. A significant positive energy harvesting from black liquor can be achieved for further development.