This study proposed a comprehensive evaluation method for rice husk combustion in rural areas. The evaluation was considered with the aspects of economic value of energy as conventional evaluation criterion, environmental impact, and economic value of rice husk charcoal in the recycling system. Inventory analysis was conducted to estimate material and energy flow for inputs and outputs of a rice husk burner (Kaneko Agricultural Machinery Co. Ltd. Saitama, Japan). Inventory data was collected for the combustion experiment using the rice husk burner. Results revealed that 14.4 kg-fuel/h of rice husk supply was the highest value of overall evaluation, because of producing valuable rice husk charcoal as by-product and small quantity of harmful substances in rice husk combustion. Trade-off relationship between economic value of energy, environmental impact, and the economic value of rice husk charcoal was observed in variations of the integrated result. It was clarified that the comprehensive evaluation method contributed to achieve high economic value of energy, low environmental impact, and high economic value of RHC simultaneously.
This study deals with an innovative design of integrated crude palm oil (CPO) and palm kernel oil processes based on process integration technology. Two types of cogeneration systems were introduced in this integrated process to further improve energy efficiency: a conventional boiler based cogeneration system and an internal combustion engine based cogeneration system. The solid wastes, including empty fruit bunches, fibers and nut shells, are used as fuel for boiler based cogeneration. Moreover, in the internal combustion engine based cogeneration, biogas is produced from the palm oil mill effluent exhausted from the CPO milling process. Energy analysis of the proposed integrated system was performed in terms of energy demand and patterns in both milling processes. The results show clearly the significant energy surplus in both milling processes. Furthermore, the huge potential of CPO and palm kernel oil mills in terms of both oil and energy production has the ability to increase national energy security in Indonesia.
Rice bran contains useful components such as starch, fiber, and protein. In this study, we investigated the use of rice bran as an inexpensive nutrient supplement for the growth of yeast in simultaneous saccharification and fermentation (SSF) for bioethanol production from rice straw. We found that rice bran was as effective a nutrient as corn steep, which is the yeast nutrient typically used in SSF. The addition of rice bran during SSF also increased the sugar concentration, thus improving the initial growth rate of the yeast cells and rapidly creating a stable SSF condition as well as increasing the final ethanol concentration. In the lab-scale experiment, the final ethanol concentration reached 69.3 g/L, and the ethanol yield was 79%. Thus, we achieved highly efficient utilization of rice bran in SSF of rice straw in the lab-scale experiments, and these findings were verified in pilot-scale SSF experiments.