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Energy supply and environmental change are the challenges facing humanity today. The need to develop new, carbon neutral forms of energy is now urgent. Bio-energy is a promising option that offers both energy sustainability and greenhouse gas emissions mitigation. In 2005 biomass provided 13.4% of current world energy needs, mainly as a heating and cooking fuel in rural communities, However, even with the increasing contribution from industrially produced biomass fired heat and power, the use of bio-diesel from oil crops and ethanol derived from maize and sugar-cane, the overall percentage contribution of bio-energy to world energy needs diminishes with time. Increasing bio-energy use to supplement the world΄s energy needs will require the growing of energy crops on a large scale, entailing changes to agricultural and forestry production techniques and the identification of new bio-energy feed-stocks. The use of ethanol from maize and sugar cane to replace petrol has more than tripled in 6 years and biodiesel from the esters of oil from crops such as palm, soya and oil seed rape now contributes 4% of Europe΄s diesel needs. However these first generation biofuels use valuable arable land and food crops in competition with human food needs and are not efficient energy producers per hectare of land nor do they effectively mitigate greenhouse gas emissions. Ligno-cellulosic ethanol, bio-butanol, bio-gas and biodiesel from gas to liquid bio-refineries using native grasses, Miscanthus, wood processing waste and short rotation coppice willow and non-food oil seed plants such as Jatropha enable non arable land and non food crops to be used for second generation biofuels. In addition, autotrophic algae have been shown to exceed productivity of many oil crops in using sunlight and carbon dioxide for oil accumulation.Microbial oils can also be used as feedstock for biodiesel productions with -advantages like short life cycle, less labour intensive, less seasonal, geographical and climatic variability and easy scale up. This paper reviews first and second generation bio-energy systems for producing biofuels and investigates the potential of biotechnology to improve the sustainability and profitability of existing and future biofuels bio-energy systems. [ABSTRACT FROM AUTHOR]

With rapid economic development, energy consumption in China has tripled in the past 20 yr, exceeding 2.4 billion tons of standard coal in 2006. The search for new green energy as substitutes for the nonrenewable energy resources has become an urgent task. China has a variety of climates and is rich in potential biofuel plant species. Corn and cassava are used as the main raw materials for bioethanol production in China. At the end of 2005, bioethanol productivity had increased to 1.02 million tons produced by four companies, and bioethanol-blended petrol accounted for 20% of the total petrol consumption in China. According to the Mid- and Long-term Development Plan for Renewable Energy, the consumption of biodiesel in China will reach 0.2 million tons in 2010 and 2.0 million tons in 2020. This review is intended to provide an introduction to the distribution and development of biofuel crops and biofuel industry in China. [ABSTRACT FROM AUTHOR]

This issue of In Vitro Plant is dedicated to various aspects of biofuel research and development. The editors have sought the experts in this field and solicited manuscripts for this special issue publication from various academic institutions, government (USDA, DOE), industry (Mendel, Alellyx, Canavilas, Syngenta, Monsanto), and various countries (USA, China, Brazil, India, and Australia). This has resulted in state-of-the-art articles describing ethanol and also biodiesel research. These publications highlight the status of biofuel research across the globe and also focus on private, public, and government interests. This is especially noteworthy in that President Barack Obama has stated that renewable energy is a pivotal aspect of his policy for the USA. The objective of this introduction is to provide the reader with the pertinent background information relative to the biofuel efforts within the private sector, academia, and government laboratories. In particular, the history of biofuel research and commercialization is provided as well as a summary of the various crop systems available for biofuel production. [ABSTRACT FROM AUTHOR]

The introduction of biofuels in Slovenia is lagging behind the reference values in EU Directive on the promotion of biofuels and other renewable fuels for transport. In order to define the real possibility of achieving political objectives, a survey for Slovenia was implemented, in order to prepare development scenarios for the achievement of the agricultural, industrial and commercial potential of biofuels production in Slovenia. This contribution presents analysis of production processes and technologies of biofuel production. Mathematical model for selection of optimal biofuel production technology depending on raw material availability and economic criteria is briefly presented. Partial results related to the transformation of the closed sugar factory as one of the suitable biofuel production locations into bioethanol plant are also presented. [ABSTRACT FROM AUTHOR]

The Chinese government is stimulating the biofuels development to replace partially fossil fuels in the transport sector, which can enhance energy security, reduce greenhouse gas emissions, and stimulate rural development. Bioethanol, biodiesel, biobutanol, biogas, and biohydrogen are the main biofuels developed in China. In this chapter, we mainly present the current status of biofuel development in China, and illustrate the issues of feedstocks, food security and conversion processes. [ABSTRACT FROM AUTHOR]

Exciting recent developments in the enzymology and molecular biology of plant phenylpropanoids offer numerous opportunities to re-engineer the composition of plant biomass. Two main targets of such modifications are the optimized production of valuable compounds and reductions in the levels of less desirable products, such as the structural biopolymeric lignins. For example, the amounts of lignin biopolymers in (woody) species might be reduced, with carbon flow concurrently redirected toward production of related nonpolymeric phenylpropanoids, such as the more valuable allyl/propenyl phenols (e.g., eugenol, chavicol). Lignins are monolignol-derived polymeric end-products of the phenylpropanoid pathway (originating from the amino acids phenylalanine and tyrosine). In general, lignins represent a formidable technical challenge, particularly due to their intractable nature, for improved plant biomass utilization, for example, when considering the use of woody biomass for bioethanol production, as well as for wood, pulp, and paper manufacture. Other species-specific outcomes of the phenylpropanoid pathway, however, include metabolites such as lignans, flavonoids, and allyl/propenyl phenols. The recent discovery of the biochemical pathway resulting in the production of the more valuable liquid allyl/propenyl phenols (e.g., eugenol, chavicol, estragole, and anethole), important components of plant spice aromas and flavors, presents one potential approach to the engineering of plant metabolism in new directions. These compounds are synthesized from monolignols in two consecutive enzymatic reactions: (1) acylation of the terminal (C-9) oxygen of the monolignol forming an ester and (2) regiospecific, NAD(P)H-dependent reduction of the phenylpropanoid side chain with displacement of the carboxylate ester as leaving group. The proteins involved in the latter step are homologous to well-characterized phenylpropanoid reductases (pinoresinol-lariciresinol, isoflavone, phenylcoumaran-benzylic ether, and leucoanthocyanidin reductases), with similar catalytic mechanisms being operative. The proteins (and corresponding genes) involved in these transformations have been isolated and characterized and offer the potential of engineering plants to partially redirect carbon flow from lignin (or lignans) into these liquid volatile compounds in oilseeds, leafy or heartwood-forming tissues, or woody stems. The emerging knowledge could also potentially facilitate wood processing in pulp/paper industries and offer sources of renewable plant-derived biofuels, intermediate chemicals in polymer industries, or specialty chemicals in perfume and flavor industries. [ABSTRACT FROM AUTHOR]

Soaking in aqueous ammonia at moderate temperatures was investigated as a method of pretreatment for enzymatic hydrolysis as well as simultaneous saccharification and cofermentation (SSCF) of corn stover. The method involves batch treatment of the feedstock with aqueous ammonia (15–30 wt%) at 40–90°C for 6–24 h. The optimum treatment conditions were found to be 15 wt% of NH3, 60°C, 1:6 of solid-to-liquid ratio, and 12 h of treatment time. The treated corn stover retained 100% glucan and 85% of xylan, but removed 62% of lignin. The enzymatic digestibility of the glucan content increased from 17 to 85% with 15 FPU/g-glucan enzyme loading, whereas the digestibility of the xylan content increased to 78%. The treated corn stover was also subjected to SSCF test using Spezyme-CP and recombinant Escherichia coli (KO11). The SSCF of the soaking in aqueous ammonia treated corn stover resulted in an ethanol concentration of 19.2 g/L from 3% (w/v) glucan loading, which corresponds to 77% of the maximum theoretical yield based on glucan and xylan. [ABSTRACT FROM AUTHOR]

Industrial production of bioethanol from fibers that are unusable for pulp production in pulp mills offers an approach to product diversification and more efficient exploitation of the raw material. In an attempt to utilize fibers flowing to the biological waste treatment, selected fiber sludges from three different pulp mills were collected, chemically analyzed, enzymatically hydrolyzed, and fermented for bioethanol production. Another aim was to produce solid residues with higher heat values than those of the original fiber sludges to gain a better fuel for combustion. The glucan content ranged between 32 and 66% of the dry matter. The lignin content varied considerably (1–25%), as did the content of wood extractives (0.2–5.8%). Hydrolysates obtained using enzymatic hydrolysis were found to be readily fermentable using Saccharomyces cerevisiae. Hydrolysis resulted in improved heat values compared with corresponding untreated fiber sludges. Oligomeric xylan fragments in the solid residue obtained after enzymatic hydrolysis were identified using matrix-assisted laser desorption ionization-time of flight and their potential as a new product of a pulp mill-based biorefinery is discussed. [ABSTRACT FROM AUTHOR]

Lignocellulosic materials represent an abundant feedstock for bioethanol production. Because of their complex structure pretreatment is necessary to make it accessible for enzymatic attack. Steam pretreatment with or without acid catalysts seems to be one of the most promising techniques, which has already been applied for large variety of lignocellulosics in order to improve enzymatic digestibility. During this process a range of toxic compounds (lignin and sugar degradation products) are formed which inhibit ethanol fermentation. In this study, the toxicity of hemicellulose hydrolysates obtained in the steam pretreatment of spruce, willow, and corn stover were investigated in ethanol fermentation tests using a yeast strain, which has been previously reported to have a resistance to inhibitory compounds generated during steam pretreatment. To overcome bacterial contamination, fermentations were carried out at low initial pH. The fermentability of hemicellulose hydrolysates of pretreated lignocellulosic substrates at low pH gave promising results with the economically profitable final 5 vol% ethanol concentration corresponding to 85% of theoretical. Adaptation experiments have shown that inhibitor tolerance of yeast strain can be improved by subsequent transfer of the yeast to inhibitory medium. [ABSTRACT FROM AUTHOR]