微藻生物柴油的发展

微藻生物柴油是一种具有较大发展潜力的可再生能源,与动、植物为原料制备的生物柴油相比,它有不占用耕地、产油效率高等优点。目前,微藻生物柴油在国内外都有很大发展,产业化的进程也在逐步推进。介绍了高油脂含量微藻的种类、微藻合成油脂的机理研究、微藻的培养技术及微藻生物柴油的产业化现状,并对微藻生物柴油发展中的一些问题进行了分析。     

富油脂微藻育种技术研究进展

微藻因生长迅速、光合作用效率高、分布范围广和油脂积累能力强等优势,已被认为是生产生物柴油的理想原料。诱变育种可改善野生型微藻生长缓慢、油脂含量低和环境适应能力弱等缺陷,提高了以微藻生产生物柴油的可行性。概述了物理、化学和基因工程三类诱变育种方法的研究现状,介绍了低场核磁共振和荧光激活细胞分选两种富油脂微藻筛选技术以及一种测定诱变藻株致死率的方法,讨论了三种诱变方法的应用前景,供相关研究人员参考。     

产油微藻的筛选及大规模培养的研究进展

产油微藻具有生长速度快、油脂含量高和抗逆性强等特点,是极具生产潜力的生物柴油的原料.微藻生物柴油技术包括微藻藻种的筛选、大量培养和采收、油脂的提取和生物柴油的制备.该文对近些年产油微藻藻种的筛选和规模化培养的研究进展进行综述.     

微藻减排CO2制备生物柴油的研究进展

碳减排与可再生能源的开发利用是研究可持续发展的热点,而微藻在此方面具有巨大优势.利用微藻减排CO2合成生物柴油生产原料油脂,对于解决能源短缺和全球变暖具有重大战略意义.将碳减排与微藻生物柴油的制备方法相结合,对微藻转化CO2合成生物油脂的机制,微藻油脂积累的影响因素以及国内外在工业上的研究概况等方面进行综合归纳和评述,并对微藻生物油脂的发展前景进行了展望.     

利用基因工程技术提高微藻油脂含量的研究进展

利用微藻油脂制备生物柴油因具有重要的战略意义而受到世界各国的重视,成为近年来的研究热点。利用微藻制备生物柴油具有生长周期短、易于大规模培养、能大量吸收CO2及不占用耕地等优点。但是,由于对藻类油脂合成代谢中的调节机制了解不多,导致微藻基因组研究相对滞后,极大地限制了微藻生物能源的大规模开发和利用。随着现代生物技术的发展,通过基因工程、代谢工程等方法调控微藻脂类的合成代谢,提高藻类含油量和生物量已成为可能。概述了微藻中油脂的合成代谢,归纳总结利用基因工程技术提高微藻油脂含量的研究进展,为获得含油量高的工程微藻及微藻制备生物柴油提供技术储备。     

基于模糊综合评价的产生物柴油微藻藻种筛选

产生物柴油微藻大规模培养对微藻藻种的性能要求较高。从丰富的藻种资源中筛选到高品质的藻种一直是个亟待解决的问题。通过研究3株产油微藻,从系统工程的角度综合整个微藻生物柴油的技术工艺,建立了以生长速率、含油率、油脂组成等18种指标的二级评价体系,采用二级模糊综合评价的模糊数学方法对产生物柴油微藻的性能进行综和分析、筛选。最终确定供评价的三株微藻二级模糊综合评价集：小球藻LICME001［0.360 0.315 0.192 0.069 0.064］,微绿球藻LICME002［0.277 0.331 0.236 0.104 0.052］和葡萄藻LICME003［0.325 0.371 0.232 0.071 0.060］。根据最大隶属度法则分析得：小球藻LICM001株产生物柴油微藻品质为优等级别,适合产生物柴油的技术工艺要求;微绿球藻LICME002和葡萄藻LICME003为良等级别的产生物柴油藻种。     

微藻生物能源研究取得新进展

中国科学院青岛生物能源与过程研究所能源藻类资源团队刘天中研究员针对微藻生物柴油生产成本和能耗影响大的微藻油脂提取、微藻生物柴油转化等下游关键技术进行了系列研究,结果发表在《Biore-sourceTechnology》杂志上。     

生物柴油研究进展

介绍了国内外生物柴油的发展现状,探讨了我国发展生物柴油的原料来源途径,包括木本油料植物、转基因油料作物、废弃油脂、微生物油脂和微藻油脂等,综述了制备生物柴油的化学法、酶法、超临界法等生产技术及其进展,概括了当前生物柴油主要的品质问题与改性对策,分析了生物柴油副产物的高值化利用策略,指出了我国生物柴油产业化面临的原料、技术和生物炼制方面的主要问题。     

产生物柴油微藻培养研究进展

石油的大量使用会导致能源枯竭和温室气体（CO2）排放的增加。为了实现经济和环境的和谐发展,必须使用可再生能源代替石油。可再生能源使用后不会造成温室气体排放的增加。生物柴油是一种理想的可再生能源, 能满足以上要求,所以近年来得到迅速发展。微藻是一种主要利用太阳能固定 CO2,生成制备生物柴油所需油脂的藻类。因此以微藻油脂为原料转化成的生物柴油是石油理想的替代品。简要介绍了产油微藻的种类和微藻油脂的合成,较详细地阐述了微藻自养培养、异养培养、生物反应器、工程微藻的最新研究进展,并初步展望了微藻产油研究的未来发展方向。     

生物柴油原料资源高油脂微藻的开发利用

生物柴油作为化石能源的替代燃料已在国际上得到广泛应用。至今生物柴油的原料主要来自油料植物, 但与农作物争地的情况以及较高的原料成本限制了生物柴油的进一步推广。微藻作为高光合生物有其特殊的原料成本优势, 微藻的脂类含量最高可达细胞干重的80%。利用生物技术改良微藻, 获得的高油脂基因工程微藻经规模养殖, 可大大降低生物柴油原料成本。介绍了国内外生物柴油的应用现状, 阐述了微藻作为生物柴油原料的优势, 对基因工程技术调控微藻脂类代谢途径的研究进展, 以及在构建工程微藻中面临的问题和应采取的对策进行了综述和展望。     

二氧化碳减排产柴油微藻培养体系研究进展

污水资源化、二氧化碳减排及微藻生物柴油是当前能源与环境领域的前沿课题。以下围绕污水及烟道气资源化培养产油微藻的培养体系,就藻种、营养条件、培养方式、培养环境及微藻生物反应器等影响产油微藻培养的因素研究进展进行了综述。在综述的基础上提出：由于微藻具有特殊营养方式,通过藻种筛选、微藻营养条件和培养环境的优化以及高效光生物反应器和生产工艺等的创新,可利用污水进行产油微藻生产,以获得生物柴油等高附加值产品,实现微藻生物能源、污水资源化处理和CO2减排三者高度耦合的产油微藻生产体系,从而减少微藻培养费用及污水处理费用,因此,该体系具有重要的环境、社会、经济价值和商业化应用前景。     

Comparative life cycle assessment of autotrophic cultivation of Scenedesmus dimorphus in raceway pond coupled to biodiesel and biogas production

Life cycle assessment (LCA) of indigenous freshwater microalgae, Scenedesmus dimorphus, cultivation in open raceway pond and its conversion to biodiesel and biogas were carried out. The LCA inventory inputs for the biogas scenario was entirely based on primary data obtained from algal cultivation (in pilot scale raceway pond), harvesting, and biogas production; while only the downstream processing involved in biodiesel production namely drying, reaction and purification were based on secondary data. Overall, eight scenarios were modeled for the integrated process involving: algae-based CO₂ capture and downstream processing scenarios for biodiesel and biogas along with impact assessment of nutrient addition and extent of recycling in a life cycle perspective. The LCA results indicated a huge energy deficit and net CO₂ negative in terms of CO₂ capture for both the biodiesel and biogas scenarios, majorly due to lower algal biomass productivity and higher energy requirements for culture mixing. The sensitivity analysis indicated that variability in the biomass productivity has predominant effect on the primary energy demand and global warming potential (GWP, kg CO₂ eq.) followed by specific energy consumption for mixing algal culture. Furthermore, the LCA results indicated that biogas conversion route from microalgae was more energy efficient and sustainable than the biodiesel route. The overall findings of the study suggested that microalgae-mediated CO₂ capture and conversion to biodiesel and biogas production can be energy efficient at higher biomass productivity (> 10 g m⁻² day⁻¹) and via employing energy-efficient systems for culture mixing (< 2 W m⁻³).

     

我国微藻生物柴油的研究背景与发展战略

生物柴油是可再生能源开发利用的重要发展方向。藻类制备生物柴油具有产油量高、生长速度快、环境适应能力强、不与农作物争夺农田和淡水资源等优势。从微藻制备生物柴油着手,简要介绍了生物柴油的生产原料与发展历程、微藻油脂的组成与生物合成途径、微藻制备柴油的工艺与瓶颈及解决策略,最后对微藻制备生物柴油技术提出了近中远期发展目标及展望。     

An alternative strategy for enhancing lipid accumulation in chlorophycean microalgae for biodiesel production

Oleaginous microalgae are considered as important feedstocks for production of biodiesel. Under nutrient stress conditions, microalgae have the ability to accumulate higher amount of lipids, which can be transesterified for the production of biodiesel. In the present investigation, four different phosphate application strategies were examined in five green microalgae (Tetradesmus obliquus, Tetradesmus lagerheimii, Chlorella vulgaris, Chlorella minutissima, and Chlamydomonas sp.) to achieve higher lipid productivity. Effects of those strategies such as phosphate-sufficient (Control), phosphate-starved approach (PSA), biphasic phosphate-starved approach (BPSA), and sequential phosphate addition (SPA) were studied under batch culture mode. The BPSA emerging as the best in terms of lipid productivity consisted of two biomass harvesting phases, which would lead to an increase in the overall cost of biodiesel production. On the other hand, the SPA with a 1/200th dose of N 11 medium, i.e., 0.4 mg L^?1 of phosphate application in 3-day intervals, also resulted into higher lipid productivity which was equal to BPSA. Fatty acid composition of the biodiesel obtained from the microalgae was analyzed and the fuel characteristics were also evaluated. A profound (~14-fold) reduction in phosphorus requirements under the SPA mode with higher lipid productivity ensured qualitative biodiesel production and a lesser amount of phosphorus release, thus making the process eco-friendly.     

微藻油脂合成代谢途径及调控机制的研究进展

随着经济的快速发展,各国对石油的需求仍有增无减,但是石油作为不可再生能源不利于可持续发展。相比之下,生物柴油应运而生且已发展到了第三代,而微藻作为第三代生物柴油的主角因为具有生长速度快,不占用耕地等优势,已逐渐成为具有极大发展潜力的能源原料,所以利用微藻生产生物柴油的技术近年来也成为研究的重点。本综述针对微藻容易进行基因改造的优势,综述了国内外对微藻油脂代谢通路的研究现状及进展,讨论了目前的基因改造方法对通路中关键酶产生的影响,以求找到能有效并稳定增强微藻油脂代谢途径的方法,为以后的研究提供理论指导。     

Biodiesel production with microalgae as feedstock: from strains to biodiesel

Due to negative environmental influence and limited availability, petroleum-derived fuels need to be replaced by renewable biofuels. Biodiesel has attracted intensive attention as an important biofuel. Microalgae have numerous advantages for biodiesel production over many terrestrial plants. There are a series of consecutive processes for biodiesel production with microalgae as feedstock, including selection of adequate microalgal strains, mass culture, cell harvesting, oil extraction and transesterification. To reduce the overall production cost, technology development and process optimization are necessary. Genetic engineering also plays an important role in manipulating lipid biosynthesis in microalgae. Many approaches, such as sequestering carbon dioxide from industrial plants for the carbon source, using wastewater for the nutrient supply, and maximizing the values of by-products, have shown a potential for cost reduction. This review provides a brief overview of the process of biodiesel production with microalgae as feedstock. The methods associated with this process (e.g. lipid determination, mass culture, oil extraction) are also compared and discussed.     

Characterization of the acylglycerols and resulting biodiesel derived from vegetable oil and microalgae (Thalassiosira pseudonana and Phaeodactylum tricornutum)

Algal biofuels are a growing interest worldwide due to their potential in terms of sustainable greenhouse gas displacement and energy production. This article describes a comparative survey of biodiesel production and conversion yields of biodiesel via alkaline transesterification of acylglycerols extracted from the microalgae Thalassiosira pseudonana and Phaeodactylum tricornutum, grown under silicate or nitrate limitation, and that of model vegetable oils: soybean, and rapeseed oil. Acylglycerols were extracted with n-hexane and the total yield per biomass was determined by gravimetric assay. Under our conditions, the total acylglycerol yield from the microalgae studied was 13-18% of total dry weight. The biodiesel samples were analyzed using gas chromatography-flame ionization detector to determine quantitative information of residual glycerol, mono-, di-, and tri-acylglycerol concentrations in the biodiesel. All of the algal-based biodiesel demonstrated less mono-, di-, and tri-acylglycerol concentrations than the vegetable-based biodiesel under identical transesterification conditions. The fatty acid compositions of all the feedstock oils and their resultant biodiesel were also analyzed and reported. Based on the fatty acid methyl ester compositions of our samples we qualitatively assessed the suitability of the algal-derived biodiesel in terms of cetane number (CN), cold-flow properties, and oxidative stability.     

Effects of outdoor cultures on the growth and lipid production of <Emphasis Type="Italic">Phaeodactylum tricornutum</Emphasis> using closed photobioreactors

One of the principal challenges for large scale production of microalgae is the high costs of biomass production. Aiming for minimize this problem, microalgal biodiesel production should focus on outdoors cultures, using available solar light and allowing lower energy cost process. Testing species that proved to be common and easy to culture may be a good approach in this process. The present work reports indoor-outdoor cultures of Phaeodactylum tricornutum using different bioreactors types, using cell growth, biochemical composition, and the profiles of the fatty acids produced as the parameters to test the optimization processes. The results show that the use of outdoor cultures is a good choice to obtain P. tricornutum biomass with a good potential for biodiesel production. The microalgae produced reached better growth efficiency, major lipid content and showed an increment in the percentage of saturated fatty acids (required on the biodiesel production) respect indoor cultures. These results are important to show the relevance of using outdoor cultures as a way to improve the efficiency and the energetic balance of the biodiesel production with P. tricornutum algae.     

Assessment and comparison of the properties of biodiesel synthesized from three different types of wet microalgal biomass

In recent years, microalgae-based carbon-neutral biofuels (i.e., biodiesel) have gained considerable interest due to high growth rate and higher lipid productivity of microalgae during the whole year, delivering continuous biomass production as compared to vegetable-based feedstocks. Therefore, biodiesel was synthesized from three different microalgal species, namely Tetraselmis sp. (Chlorophyta) and Nannochloropsis oculata and Phaeodactylum tricornutum (Heterokontophyta), and the fuel properties of the biodiesel were analytically determined, unlike most studies which rely on estimates based on the lipid profile of the microalgae. These include density, kinematic viscosity, total and free glycerol, and high heating value (HHV), while cetane number (CN) and cold filter plugging point (CFPP) were estimated based on the fatty acid methyl ester profile of the biodiesel samples instead of the lipid profile of the microalgae. Most biodiesel properties abide by the ASTM D6751 and the EN 14214 specifications, although none of the biodiesel samples met the minimum CN or the maximum content of polyunsaturated fatty acids with ≥4 double bonds as required by the EN 14214 reference value. On the other hand, bomb calorimetric experiments revealed that the heat of combustion of all samples was on the upper limit expected for biodiesel fuels, actually being close to that of petrodiesel. Post-production processing may overcome the aforementioned limitations, enabling the production of biodiesel with high HHV obtained from lipids present in these microalgae.     

Energy recovery from lipid extracted,transesterified and glycerol codigested microalgae biomass

The production of methane (CH₄) via the anaerobic digestion of microalgae biomass residues from the biodiesel production process has the potential to meet some of the energy requirements of the primary biomass to fuel conversion process. This paper investigates the practical CH₄ yields achievable from the anaerobic conversion of the microalgae residues (as well as codigestion with glycerol) after biodiesel production using both the conventional and in situ transesterification methods. Results demonstrate that the type of lipid extraction solvent utilized in the conventional transesterification process could inhibit subsequent CH₄ production. On the basis of actual CH₄ production, a recoverable energy of 8.7–10.5 MJ kg^?1 of dry microalgae biomass residue was obtained using the lipid extracted and transesterified microalgae samples. On codigesting the microalgae residues with glycerol, a 4–7% increase in CH₄ production was observed.