成果報告書詳細
管理番号20140000000085
タイトル*平成25年度中間年報 バイオマスエネルギー技術研究開発 戦略的次世代バイオマスエネルギー利用技術開発事業(次世代技術開発) 高油脂生産微細藻類の大規模培養と回収および燃料化に関する研究開発
公開日2014/5/2
報告書年度2013 - 2013
委託先名株式会社デンソー 学校法人中央大学 株式会社クボタ 出光興産株式会社
プロジェクト番号P10010
部署名新エネルギー部
和文要約藻類バイオ燃料を商業レベルの価格にまで下げるためには、培養工程における、水道代と人件費、電力代を大幅に削減する必要がある。そこで本事業では、1)培養水のリサイクル技術の開発、2)自動化培養システムの開発、3)培養の省エネ化、を大きな課題項目として取り上げている。H25年度は、培地中の有機物を除去する方法について検討を進め、シラスを用いた有機物分解試験により、TOC を1/10 に低減可能である事を確認した。藻の回収技術の開発については、1 段目濃縮に適した分離膜、及び運転方法の開発に成功し、本プロセスの長期安定性を確認した。また、セラミック膜を使った2 段目濃縮プロセスの有用性を改めて示した。燃料化研究については、既存の植物油脂精製の改良法により、シュードクルード油から、アルカリ、アルカリ土類、リン等の不純物を除去できる事を確認した。一方、塩素については上記方法では除去できず、次期への課題が明確になった。
英文要約R&D on Mass Cultivation and Harvesting of Microalgae with high oil content and Hydrotreating Process for biofuel production.

Microalgal-derived biofuel is recognized as a third generation biofuel, because it does not compete with food and has a high potential for accumulating oil. We have to develop i) energy-saving and automatic cultivation system, ii) harvesting processes, and iii) catalyst technology for producing drop-in fuel toward the practical use.
We have some plans to reduce cultivation costs to a practical level, such as improving water recycle technologies, developing automation system and reducing the power consumption required for the culture. The most important issue for the water recycle technologies is a reduction of water-soluble organic matter in a culture broth, because it would cause protozoa contamination problem. If the contamination problem has occurred in a broth, the automated cultivation system cannot be realized. Therefore, we had studied how to remove the organic matter in a broth this fiscal year. As the water-soluble organic carbon level in a broth is not high, we selected sand filtration system. We have succeeded in reducing the water-soluble organic matter by using Sirasu as a carrier of bacteria under acidic condition. We will study how to improve the degradation efficiency and provide the best conditions for bacteria from now.
For the cell harvesting process, membrane filtration has been gaining popularity instead of coagulation-flotation or centrifugation process, because it can easily concentrate the algae cells more than 60 g/L with a low energy consumption. The major drawback of this technology is membrane fouling, which increase the operation cost to a large extent as a result of reduction of membrane permeability. For more efficient use of membrane, we should increase the operation flux to 4.0 m3/m2/day, but it is still difficult to be achieved with the normal membrane and general washing condition. In this study, we prepared the novel hollow fiber membrane having the nominal pore size of 2.0 μm and optimized the washing condition to achieve the 30-times concentration with operation flux of 4.0 m3/m2/day. As a result of the use of novel membrane and optimal washing condition, we could achieve 30-fold concentration with a flux of 4.0 m3/m2/day. Furthermore, the final trans-membrane pressure was low enough (60kPa), implying that there was a possibility to be able to set higher operation flux or higher concentration level.
In addition, we examined the membrane module shape and operation conditions using a novel ceramic membrane toward the higher concentration. Thereafter, fundamental experiments were performed to evaluate the ability of the two-step filtration system, we confirmed the high concentration efficiency of over 120-times. In the next study, we are planning to optimize the operating conditions to ensure a high concentration rate and operating flux.
Our goal is to produce “drop-in fuel” meeting practical use. In this study, hydro-treated bio-jet (HBJ) and hydro-treated bio-diesel (HBD) are the corresponding fuels. The process to obtain these fuels consists of four steps; “pre-treatment”, “hydro-deoxidation”, “hydro-cracking & isomerization” and “fuel design”. In the fiscal year of 2013, we had studied the “pre-treatment” technology to remove metals and halogens in the micro-algal derived crude oil. All the metals were successfully removed to the target value by modifying a purification method for cooking oils and applying it to the crude oil. The elimination of halogen compounds is a remaining task, requiring further study.
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