酵母菌复合培养物对木质纤维素稀酸水解液原位脱毒乙醇发酵

为了解决木质纤维素稀酸水解产物中发酵抑制剂对微生物的抑制作用以及木糖的乙醇发酵问题,该研究用本实验室开发的能高效代谢葡萄糖产乙醇并代谢糠醛和5-羟甲基糠醛的2株酵母菌种Saccharomyces cerevisiae Y5和Ismtchenkia/orientalis Y4分别与Pichia.stipitis CBS6054组成2个复合菌种,用复合菌种对木质纤维素稀酸水解产物进行原位脱毒乙醇发酵.结果证明,复合菌种S.cerevisiae Y5,P.stipitis CBS6054显示出了很好的代谢稀酸水解液中的葡萄糖和木糖产乙醇并快速代谢糠醛和5-羟甲基糠醛的能力,乙醇产率为0.43g/g(达到理论值的85.1%).该复合培养物可作为木质纤维索稀酸水解产物不需任何脱毒处理直接进行乙醇发酵的复合菌种.     

固定化细胞木质纤维素稀酸水解液乙醇发酵研究

利用不同菌种的固定化细胞对木质纤维素稀酸水解液进行乙醇发酵,对2#菌进行了以木糖为底物7个批次的驯化培养。利用4#与1#的混合菌及3#菌进行批式发酵以及4#和1#、1#和3#、4#和3#混合菌及3#菌进行补料批式发酵,结果表明,1#和4#及1#和3#混合固定化对木质纤维素稀酸水解液进行补料批式发酵,乙醇产率较为理想,分别为理论产率的79.3%和84.3%。     

木质纤维素稀酸水解液乙醇发酵的新方法

为了降低木质纤维素水解液发酵抑制剂对乙醇发酵的负影响,采用混合菌种对木质纤维素稀酸水解液乙醇发酵方式进行了研究。对批式发酵、补料批式发酵和间隔补料批式发酵3种发酵方式进行了比较。实验结果表明,间隔补料批式发酵可以有效地减弱水解液中抑制因子对菌种的影响,乙醇产量明显高于其他两种发酵方式,利用酿酒酵母(Saccaromyces cerevisiae 2.535)和嗜鞣管囊酵母(Pachysolen tannophilis ATCC 32728)混合发酵,乙醇产量最终达到14.4g/L,乙醇产率(Yp/s)为0.47g/g,相当于最大理论产率的92.2%。利用酿酒酵母和重组大肠杆菌混合菌种发酵,乙醇产量达到了14.5g/L。对木质纤维素稀酸水解液采用间隔补料批式乙醇发酵方法,可进一步减少抑制剂对乙醇发酵的影响,使发酵顺利进行。     

两株高效代谢木质纤维素稀酸水解物产乙醇的酵母特性及耐毒研究

对实验室筛选出的两株高效代谢木质纤维素稀酸水解液产乙醇的酵母菌Y1(Candida tropicalis)和Y4(Issatchenkiaorientalis)的乙醇发酵特性及耐毒能力进行了的研究。以未经任何脱毒处理的木质纤维素稀酸水解液为发酵底物进行乙醇发酵(原位脱毒乙醇发酵)。结果表明,Y1和Y4均能在24h内将水解液中所有的葡萄糖消耗完,乙醇产率分别为0.49g/g和0.45g/g,分别达到了理论值的96.1%和86.0%。在含有不同浓度梯度的糠醛及5-羟甲基糠醛的模拟水解液中,Y1和Y4能耐受的最高糠醛浓度均为5.0g/L,最高的5-羟甲基糠醛浓度均大于7.0g/L,当两种抑制剂等量混合时,两株菌能耐受的最高浓度为4.0g/L。两株菌均有较好的乙醇发酵及耐毒能力。该研究结果为木质纤维素水解液的原位脱毒发酵生产然料乙醇奠定了基础。     

木质纤维素稀酸水解液游离细胞乙醇发酵

为了对木质纤维素稀酸水解液进行游离细胞乙醇发酵,采用了混合菌种与不同发酵方式对稀酸水解液的乙醇发酵进行了研究。通过对1#菌和2#菌以及1#菌和3#菌两组混合菌种的驯化,得到了能耐受一定浓度的发酵抑制因子并产生较高乙醇产量的菌株。用1#菌和2#菌混合菌种以及1#菌和3#菌混合菌种进行批式发酵,72h内乙醇产率分别为0.49g/g和0.45g/g,达到了理论产率的96.1%和88.5%。对补料批式发酵进行的初步研究也取得了比较好的结果。     

燃料酒精生产中对木质纤维素稀酸水解液的脱毒处理

用稀酸水解农业废弃物秸秆、木材加工废物等木质纤维素产生糖，再将这些糖发酵成燃料酒精，是利用农林废弃物等生物质生产清洁燃料的途径之一。为使木质纤维素产生糖，通常采用理化结合的方法，在高温、高压和催化剂稀酸的作用下水解木质纤维素，例如，用稀酸140-160℃或者更高温度处理木质纤维素即可得到含糖水解液。在该水解过程中，虽然含有葡萄糖、木糖、阿拉伯糖等可发酵产酒精的混合糖，但由于反应条件剧烈，还会含有许多对酒精发酵微生物有毒性作用的抑制物，称之为发酵抑制剂，这些发酵抑制剂浓度随水解反应条件的剧烈程度和木质纤维素的种类不同而不同。水解液中的抑制剂主要有：糠醛、羟甲基糖醛、乙酸、酚类化合物、丁香酸、羟基苯甲酸、香草醛及其它有毒化合物。     

木质纤维素两步稀酸低温水解研究

为了降低水解液中抑制剂的浓度,对木质纤维素采用两步稀酸低温水解,通过对两步稀酸水解中重要参数(温度,反应时间,硫酸浓度)的研究,得到第一步水解的最佳条件为:温度135℃,反应时间2h,硫酸1.5%;第二步水解最佳条件为:温度135℃,反应时间2h,硫酸3.0%。以秸秆为原料得到的糖浓度可达5%。采用嗜鞣管囊酵母对水解软木所得水解液进行乙醇发酵实验,24h乙醇产率为0.41g/g,达到最大理论产率的80.4%。乙醇发酵实验证明,两步稀酸低温水解物对乙醇发酵没有抑制作用。     

两株高效代谢木质纤维素稀酸水解物产乙醇的酵母特性及耐毒研究

对实验室筛选出的两株高效代谢木质纤维素稀酸水解液产乙醇的酵母菌Y1(Candida tropicalis)和Y4(Issatchenkiaorientalis)的乙醇发酵特性及耐毒能力进行研究。以未经任何脱毒处理的木质纤维素稀酸水解液为发酵底物进行乙醇发酵(原位脱毒乙醇发酵)。结果表明:Y1和Y4均能在24h内将水解液中所有的葡萄糖消耗完,乙醇产率分别为0.49g/g和0.45g/g,分别达到理论值的96.1%和86.0%。在含有不同浓度梯度的糠醛及5-羟甲基糠醛的模拟水解液中,Y1和Y4能耐受的最高糠醛浓度均为5.0g/L及最高的5-羟甲基糠醛浓度均大于7.0g/L,当两种抑制剂等量混合时,两株菌能耐受的最高浓度为4.0g/L,两株菌均有较好的乙醇发酵及耐毒能力。该研究结果为木质纤维素水解液的原位脱毒发酵生产然料乙醇奠定了基础。     

高耐毒性酿酒酵母的紫外诱变选育

木质纤维素生产乙醇已成为世界各国研究开发的热点.但在酿酒酵母对木质纤维素稀酸水解产物的乙醇发酵中,对水解产物中的毒性物质非常敏感.菌种对水解液毒性物质耐受力相对较低是影响木质纤维素乙醇发酵工业化的主要因素之一.利用紫外线对酿酒酵母进行诱变,得到2株高效耐水解液中毒性物质突变株k和n.2株突变株发酵未脱毒的木屑稀酸水解产物的乙醇产量分别达到理论值的71.0%和61.3%,为进一步提高酿酒酵母耐毒性的研究和木质纤维素稀酸水解生产乙醇的工业化提供了基础.     

木质纤维素类生物质稀酸水解技术研究进展

稀酸水解技术被广泛应用于木质纤维素类生物质制取燃料乙醇,是目前经济性最好的酶水解预处理技术.文章从稀酸水解工艺出发,综述了近年来稀酸水解技术中非常有发展前景的高温液态水和超低酸水解技术在国内外的研发现状,归纳了常用的5种水解反应器的处理性能,并对比分析了其优缺点,最后提出了稀酸水解技术在工艺及反应器设计方面的发展方向,为后续研究打下了基础.     

论国内发展燃料乙醇的优势及前景

燃料乙醇是世界范围内新兴的替代能源之一。介绍了燃料乙醇的清洁性以及巨大的市场潜力,分析了国内发展燃料乙醇工业的优势及前景,并指出燃料乙醇是油品品质改良剂。     

我国推广使用变性燃料乙醇的环境影响评价

为了解决环境问题和确保国家能源安全,世界各国都在研发可替代能源和清洁能源。变性燃料乙醇是重要的可再生能源之一,目前我国正在试点使用含10%乙醇的乙醇汽油,推广使用乙醇汽油可以综合缓解我国石油短缺、环境恶化和粮食过剩三大热点问题。本文结合国际开展政策性战略环境影响评价的思路和方法,分析推广使用变性燃料乙醇后对环境所产生的影响,得出推广使用变性燃料乙醇具有明显的经济效益、社会效益和环境效益,有利影响远远大于不利影响的结论。最后本文提出推广使用变性燃料乙醇的措施,为在我国顺利推广乙醇汽油提供决策支持。     

Multi-objective optimization of cassava-based fuel ethanol used as an alternative automotive fuel in Guangxi,China

Multi-objective optimization of net energy, external costs of environment pollutant-emissions, and cost of using cassava-based fuel ethanol as an alternative automotive fuel in Guangxi has been conducted based on its holistic life cycle, from feedstock production to fuel combustion. A new indicator, cost of net energy (CNE), linking net energy-yield, external cost of environment pollutant-emissions, and production cost (the lower the CNE reading, the better the total performance) of ethanol–gasoline blends, is proposed for carrying out multi-objective optimization. On the life-cycle basis, CNE of ethanol–gasoline blends is found to obtain its lowest value, i.e. 0.119  RMB/MJ, when processing fuel during the ethanol conversion stage was natural gas and the ratio of ethanol blended with gasoline was 5%. From the standpoint of the CNE indicator, the most viable implement form of cassava-based fuel ethanol should be used as one of oxygenate additives. The recommended processing fuel during ethanol conversion stage should be natural gas.     

Review: Direct ethanol fuel cells

Direct ethanol fuel cells have attracted much attention recently in the search for alternative energy resources. As an emerging technology, direct ethanol fuel cells have many challenges that need to be addressed. Many improvements have been made to increase the performance of direct ethanol fuel cells, and there are great expectations for their potential. However, many improvements need to be made in order to enhance the potential of direct ethanol fuel cells in the future. This paper addresses the challenges and the developments of direct ethanol fuel cells at present. It also presents the applications of DEFC.     

Life cycle economic analysis of fuel ethanol derived from cassava in southwest China

For energy security and environmental improvement reasons, the Chinese government is developing biomass ethanol as one of its transportation fuels. Cassava is a good feedstock to produce this ethanol because it has a high starch content and it is abundant in the southern provinces. A computer-based cost model has been developed to assess the life cycle economics of ethanol produced from cassava. The results are compared to gasoline as a base-line case. Although ethanol fuel is not currently competitive with conventional gasoline, these life cycle cost results indicate that, at present market prices, ethanol has the potential to be competitive if there are incentives and improved cassava yields. In addition, this renewable energy could help to alleviate poverty, improve land utilization and bring energy independence in Guangxi province in southeast China. This computer model will be an important tool for the energy policy makers to understand whether an energy alternative is cost-competitive, as well as providing a way to find appropriate measures throughout the entire life cycle that optimizes the process and removes the economic barriers.     

我国替代燃料乙醇汽油发展现状

发展车用清洁代用燃料,在发动机上实现高效、低污染的燃烧,控制汽车发动机有害排放对我国城市大气质量带来的日趋严重的影响,已成为我国能源与环境研究中的一个十分重大和紧迫的课题.研究和开发汽油的代用燃料,从近期来看能减少尾气,改善大气质量,从长远来看可以解决石油资源短缺的危机.但这要求代用燃料既要具备较高燃烧性能,又要满足低排放的要求.乙醇燃料以掺烧或纯烧方式已成功地用于汽油机上,汽油醇（gasohol）混合燃料在巴西、美国已应用多年,技术上已十分成熟.2004年2月,经国务院同意,国家发改委等8部门联合制定颁布了《车用乙醇汽油扩大试点方案》和《车用乙醇汽油扩大试点工作实施细则》,由此相关工作全面启动.     

Emergy analysis of cassava-based fuel ethanol in China

Emergy analysis considers both energy quality and energy used in the past, and compensates for the inability of money to value non-market inputs in an objective manner. Its common unit allows all resources to be compared on a fair basis. As feedstock for fuel ethanol, cassava has some advantages over other feedstocks. The production system of cassava-based fuel ethanol (CFE) was evaluated by emergy analysis. The emergy indices for the system of cassava-based fuel ethanol (CFE) are as follows: transformity is 1.10 E + 5 sej/J, EYR is 1.07, ELR is 2.55, RER is 0.28, and ESI is 0.42. Compared with the emergy indices of wheat ethanol and corn ethanol, CFE is the most sustainable. CFE is a good alternative to substitute for oil in China. Non-renewable purchased emergy accounts for 71.15% of the whole input emergy. The dependence on non-renewable energy increases environmental degradation, making the system less sustainable relative to systems more dependent on renewable energies. For sustainable development, it is vital to reduce the consumption of non-renewable energy in the production of CFE.     

Dimethyl ether (DME) as an alternative fuel

With ever growing concerns on environmental pollution, energy security, and future oil supplies, the global community is seeking non-petroleum based alternative fuels, along with more advanced energy technologies (e.g., fuel cells) to increase the efficiency of energy use. The most promising alternative fuel will be the fuel that has the greatest impact on society. The major impact areas include well-to-wheel greenhouse gas emissions, non-petroleum feed stocks, well-to-wheel efficiencies, fuel versatility, infrastructure, availability, economics, and safety. Compared to some of the other leading alternative fuel candidates (i.e., methane, methanol, ethanol, and Fischer–Tropsch fuels), dimethyl ether appears to have the largest potential impact on society, and should be considered as the fuel of choice for eliminating the dependency on petroleum.DME can be used as a clean high-efficiency compression ignition fuel with reduced NO_x, SO_x, and particulate matter, it can be efficiently reformed to hydrogen at low temperatures, and does not have large issues with toxicity, production, infrastructure, and transportation as do various other fuels. The literature relevant to DME use is reviewed and summarized to demonstrate the viability of DME as an alternative fuel.     

Environmental aspects of ethanol-based fuels from Brassica carinata: A case study of second generation ethanol

One of the main challenges faced by mankind in the 21st century is to meet the increasing demand for energy requirements by means of a more sustainable energy supply. In countries that are net fossil fuel importers, expectation about the benefit of using alternative fuels on reducing oil imports is the primary driving force behind efforts to promote its production and use. Spain is scarce in domestic energy sources and more than 50% of the energy used is fossil fuel based. The promotion of renewable energies use is one of the principal vectors in the Spanish energy policy. Selected herbaceous crops such as Brassica carinata are currently under study as potential energy sources. Its biomass can be considered as potential feedstock to ethanol conversion by an enzymatic process due to the characteristics of its composition, rich in cellulose and hemicellulose. This paper aims to analyse the environmental performance of two ethanol-based fuel applications (E10 and E85) in a passenger car (E10 fuel: a mixture of 10% ethanol and 90% gasoline by volume; E85 fuel: a mixture of 85% ethanol and 15% gasoline by volume) as well as their comparison with conventional gasoline as transport fuel. Two types of functional units are applied in this study: ethanol production oriented and travelling distance oriented functional units in order to reflect the availability or not of ethanol supply. E85 seems to be the best alternative when ethanol production based functional unit is considered in terms of greenhouse gas (GHG) emissions and E10 in terms of non-renewable energy resources use. Nevertheless, E85 offers the best environmental performance when travelling distance oriented functional unit is assumed in both impacts. In both functional unit perspectives, the use of ethanol-based fuels reduces the global warming and fossil fuels consumption. However, the contributions to other impact indicators (e.g. acidification, eutrophication and photochemical oxidants formation) were lower for conventional gasoline.Life Cycle Assessment (LCA) procedure helps to identify the key areas in the B. carinata ethanol production life cycle where the researchers and technicians need to work to improve the environmental performance. Technological development could help in lowering both the environmental impact and the prices of the ethanol fuels.     

Ethanol–electric propulsion as a sustainable technological alternative for urban buses in Brazil

The option of fitting electric motors to vehicles that are more efficient and quieter than internal combustion engines has been hampered considerably, looking only at the use of conventional batteries supplying electricity. This is basically due to low gravimetric and volumetric energy densities of these devices that result in shorter autonomy, in addition to more weight and less usable space in the vehicle. An alternative that could make electric motors more attractive for vehicular applications by replacing batteries as the main electricity source is the fuel cell. Hydrogen is the main fuel used in these cells, but the hydrogen storage systems developed so far are heavier and bulkier than their equivalent for conventional liquid fuels such as diesel, gasoline and alcohol, despite heavier energy densities compared to batteries.This paper reviews technological aspects of fuel cells, the main storage systems for hydrogen and other energy sources, data on fuel use and the types of vehicles most commonly used in the Brazilian road transportation sector, followed by an overview of the insertion of hybrid ethanol–electric buses in Brazil.