近年，一般電気事業者による火力電源調達事業を競争入札に掛けることにより，プラントの設備更新や，多様な主体による供給力増強を目指した火力電源入札制度が実施されている。本研究では，火力発電プラントのリプレース意思決定問題に関して，一般電気事業者とIPP 事業者の２者が存在する状況を考える。さらに，火力電源入札制度に着目し，燃料費の不確実性を考慮した火力発電プラントのリプレースモデルを構築し，発電事業者のリプレース意思決定に関する経済性評価を行う。特に，最適な投資のタイミング指標である閾値を導出し，火力電源入札制度を考慮したときの卸価格と入札価格が，リプレースの閾値に与える影響について分析を行う。その結果，入札価格の低下に伴いリプレースは促進される一方で，入札価格の過度な低下はリプレース機会を減少することを明らかにする。

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石灰石焼成炉用燃料として粒状廃プラスチックを用いた場合の燃焼挙動について，電気炉による試験および実機への吹き込み試験を行った。電気炉試験の結果，6 mmφの粒状廃プラスチック単一粒子の燃焼には1000℃で，約25 sec の滞留時間を要した。燃焼時間は粒状廃プラスチックの性状にも影響され，緻密なものほど燃焼時間を必要とする結果となった。実機石灰焼成炉での試験結果より，気流輸送により吹き込まれた粒状廃プラスチックは炉内吹込み直後に着火後，石灰石/ 生石灰上に落下し，石灰石と移動しながら燃焼し，粒状廃プラスチックの吹き込み速度により，燃焼位置が変化するものと考えられる。また，粒状廃プラスチックはコークス炉ガスと同等以上に熱量基準で利用できることが明らかとなった。

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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.

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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.

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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.

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