http://www.mdpi.com/journal/energies/special_issues/biofuels/ Dear Colleagues, The value of biomass as a sustainable source of energy and carbon has been heralded for years. Despite the information available on enzyme systems and plant cell walls structure, application of this knowledge to biomass conversion into biofuels and useful chemicals has met with limited success. The goal of this special issue is to examine the stand of the latest available technologies to ensure a sustainable commercial use of biomass wastes. Dr. Clifford Louime Guest Editor Papers published in another special issue on a similar topic in 2007-2008: link Submission All papers should be submitted to energies@mdpi.org with copy to the guest editor. To be published continuously until the deadline and papers will be listed together at the special websites. Submitted papers should not have been previously published nor be currently under consideration for publication elsewhere. All papers are refereed through a peer review process. A guide for authors, sample copies and other relevant information for submitting papers are available on the Instructions for Authors page. Energies is an international peer-reviewed quarterly journal published by Molecular Diversity Preservation International. Please visit the Instructions for Authors page before submitting a paper. Open Access publication fees are 300 CHF per paper. English correction fees (250 CHF) will be added in certain cases (550 CHF per paper for those papers that require extensive additional formatting and/or English corrections.). Article Processing Charges (APC) Article Processing Charges (APC) will be waived for well prepared manuscripts of invited papers. For the first two volumes of this new journal the APC are of 300 CHF (or 550 CHF per paper for those papers that require extensive additional formatting and/or English corrections). Leading Research Articles and Reviews Adsul, M.G.; Bastawde, K.B.; Varma, A.J.; Gokhale; D.V. Strain improvement of Penicillium janthinellum NCIM 1171 for increased cellulase production. Bioresour. Technol. 2007, 98,1467-73. Epub 2006 Nov 13. Saha, B.C.; Cotta, M.A. Ethanol production from alkaline peroxide pretreated enzymatically saccharified wheat straw. Biotechnol Prog. 2006, 22, 449-53 Rauscher, R.; Wurleitner, E.; Wacenovsky. C.; Aro, N.; Stricker, A.R.; Zeilinger, S.; Kubicek, C.P., Penttila, M.; Mach, R.L. Transcriptional regulation of xyn1, encoding xylanase I, in Hypocrea jecorina. Eukaryot. Cell, 2006, 5, 447-56. Old, L.A.; Lowes S.; Russell, R.R. Genomic variation in Streptococcus mutans: deletions affecting the multiple pathways of beta-glucoside metabolism. Oral Microbiol. Immunol. 2006, 21, 21-7. Baker, J.O.; McCarley, J.R.; Lovett, R.; Yu, C.H.; Adney, W.S.; Rignall, T.R.; Vinzant, T.B.; Decker, S.R.; Sakon, J.; Himmel, M.E. Catalytically enhanced endocellulase Cel5A from Acidothermus cellulolyticus. Appl. Biochem. Biotechnol. 2005, 121-124, 129-48. Wang, T.; Liu, X.; Yu, Q.; Zhang, X.; Qu, Y.; Gao, P.; Wang, T. Directed evolution for engineering pH profile of endoglucanase III from Trichoderma reesei. Biomol. Eng. 2005, 22, 89-94. Chand, P.; Aruna, A.; Maqsood, A.M.; Rao, L.V. Novel mutation method for increased cellulase production. J. Appl. Microbiol.2005, 98, 318-23. Zhou, W.; Irwin, D.C.; Escovar-Kousen, J.; Wilson, D.B. Kinetic studies of Thermobifida fusca Cel9A active site mutant enzymes. Biochemistry 2004, 43, 9655-63. Wilson, D.B. Studies of Thermobifida fusca plant cell wall degrading enzymes. Chem. Rec. 2004, 4, 72-82. Tellez-Valencia, A.; Sandoval, A.A.; Pedraza-Reyes, M. The non-catalytic amino acid Asp446 is essential for enzyme activity of the modular endocellulase Cel9 from Myxobacter sp. AL-1. Curr. Microbiol. 2003, 46, 307-10. Torney, F.; Moeller, L.; Scarpa, A.; Wang, K. Genetic engineering approaches to improve bioethanol production from maize. Curr. Opin. Biotechnol. 2007 [Epub ahead of print]. Service, R.F. Cellulosic ethanol. Biofuel researchers prepare to reap a new harvest. Science 2007, 16, 1488-91. No abstract available. Escovar-Kousen, J.M.; Wilson, D.; Irwin, D. Integration of computer modeling and initial studies of site-directed mutagenesis to improve cellulase activity on Cel9A from Thermobifida fusca. Appl. Biochem. Biotechnol. 2004, 113-116, 287-97. Stephanopoulos, G. Challenges in engineering microbes for biofuels production. Science 2007, 315, 801-4. Schubert, C. Can biofuels finally take center stage? Nat. Biotechnol. 2006, 24, 777-84. Hahn-Hagerdal, B.; Galbe, M.; Gorwa-Grauslund, M.F.; Liden, G.; Zacchi, G. Bio-ethanol--the fuel of tomorrow from the residues of today. Trends Biotechnol. 2006, 24, 549-56. Review. Farrell, A.E.; Plevin, R.J.; Turner, B.T.; Jones, A.D.; O'Hare, M.; Kammen, D.M. Ethanol can contribute to energy and environmental goals. Science 2006, 311, 506-8. Sticklen, M. Plant genetic engineering to improve biomass characteristics for biofuels. Curr. Opin. Biotechnol. 2006, 17, 315-9. Review. Gray, K.A.; Zhao, L.; Emptage, M. Bioethanol. Curr. Opin. Chem. Biol. 2006, 10, 141-6. Review. Ragauskas, A.J.; Williams, C.K.; Davison, B.H.; Britovsek, G.; Cairney, J.; Eckert, C.A.; Frederick, W.J. Jr.; Hallett, J.P.; Leak, D.J.; Liotta, C.L.; Mielenz, J.R.; Murphy, R.; Templer, R.; Tschaplinski, T. The path forward for biofuels and biomaterials. Science2006, 311, 484-9. Review. Yinbo, Q.; Zhu, M.; Liu, K.; Bao, X.; Lin, J. Studies on cellulosic ethanol production for sustainable supply of liquid fuel in China. Biotechnol. J. 2006, 1, 1235-40. Review. Jeffries, T.W. Engineering yeasts for xylose metabolism. Curr. Opin. Biotechnol. 2006, 17, 320-6. Review. Sticklen, M. Plant genetic engineering to improve biomass characteristics for biofuels. Curr. Opin. Biotechnol. 2006, 17, 315-9. Review. Percival Zhang, Y.H.; Himmel, M.E.; Mielenz, J.R. Outlook for cellulase improvement: screening and selection strategies. Biotechnol. Adv. 2006, 24, 452-81. Review. Ward, O.P.; Singh, A. Bioethanol technology: developments and perspectives. Adv. Appl. Microbiol. 2002, 51, 53-80. Review. Lynd, L.R.; Weimer, P.J.; van Zyl, W.H.; Pretorius, I.S. Microbial cellulose utilization: fundamentals and biotechnology. Microbiol. Mol. Biol. Rev. 2002, 66, 506-77. Review. Erratum in: Microbiol. Mol. Biol. Rev. 2002, 66, 739. Sun, Y.; Cheng, J. Hydrolysis of lignocellulosic materials for ethanol production: a review. Bioresour. Technol. 2002, 83, 1-11. Review. Mielenz, J.R. Ethanol production from biomass: technology and commercialization status. Curr. Opin. Microbiol. 2001, 4, 324-9. Review. Bayer, E.A.; Shimon, L.J.; Shoham, Y.; Lamed, R. Cellulosomes-structure and ultrastructure. J. Struct. Biol. 1998, 124, 221-34. Review. Davies, G.J. Structural studies on cellulases. Biochem. Soc. Trans. 1998, 26, 167-73. Review. Gray, K.A.; Zhao, L.; Emptage, M. Bioethanol. Curr. Opin.Chem. Biol. 2006, 10, 141-6. Review. Lin, Y.; Tanaka, S. Ethanol fermentation from biomass resources: current state and prospects. Appl. Microbiol. Biotechnol. 2006, 69, 627-42. Review. Louime, C.; Abazinge, M.; Johnson, E.; Latinwo, L.; Ikediobi, C. Location, formation and biosynthetic regulation of cellulases in the gliding bacteria Cytophaga hutchinsonii. Int. J. Mol. Sci. 2006, 7, 1-11. Louime, C.; Abazinge, M.; Johnson, E.; Latinwo, L.Sugarcane: Is it the new biocellulosic substrate for the biomass industry. Florida Scientist 2006, 69, 44-48. http://www.mdpi.com/1996-1073/3/2/194/ In the last five years or so, biofuels have been given notable consideration worldwide as an alternative to fossil fuels, due to their potential to reduce greenhouse gas emissions by partial replacement of oil as a transport fuel. The production of biofuels using a sustainable approach, should consider local production of biofuels, obtained from local feedstocks and adapted to the socio-economical and environmental characteristics of the particular region where they are developed. Thus, decentralized energy from waste systems will exploit local biomass to optimize their production and consumption. Waste streams such as agricultural and wood residues, municipal solid waste, vegetable oils, and algae residues can all be integrated in energy from waste systems. An integral optimization of decentralized energy from waste systems should not be based on the optimization of each single process, but the overall optimization of the whole process. This is by obtaining optimal energy and environmental benefits, as well as collateral beneficial co-products such as soil fertilizers which will result in a higher food crop production and carbon dioxide fixation which will abate climate change. http://www.mdpi.com/1996-1073/3/2/194/ Thu, 28 Jan 2010 00:00:00 CET Energies 2010-01-28 3 2 Article 194 205 1996-1073 Decentralized Energy from Waste Systems 2010-01-28 doi: 10.3390/en3020194 Blanca Antizar-Ladislao Juan L. Turrion-Gomez http://www.mdpi.com/1996-1073/2/4/1192/ This research set out to explore and develop a route relating the recycling of urban and industrial wastes to land to produce agricultural crops with energy crops in the rotation, using the green leaf to “harvest” sunlight and to examine the sequestration of carbon dioxide and release of oxygen in a sustainable closed loop. Further, to establish if the pollution, particularly of nitrogen and phosphates (often associated with cultivations and use of mineral fertilisers) could be reduced or eliminated, so as to be able to develop systems which could contribute to the reversal of global warming. Finally, to probe whether practical operators on the ground could understand the technology, use it, and express what they were doing in a way acceptable to a wider society. http://www.mdpi.com/1996-1073/2/4/1192/ Thu, 03 Dec 2009 00:00:00 CET Energies 2009-12-03 2 4 Article 1192 1200 1996-1073 The Technology of Waste, Biofuels and Global Warming in Viable Closed Loop, Sustainable Operations 2009-12-03 doi: 10.3390/en20401192 William R. Butterworth http://www.mdpi.com/1996-1073/2/4/957/ A new inclined plates extractor-separator is developed for operation with immiscible liquids in which extraction and separation is achieved in one unit contrary to mixer settlers. The inclined plates extractor-separator combines turbulent jets for contacting, and an inclined plate for separation of the two phases. The inclined plates extractor-separator does not have any moving part inside the vessel. This feature makes it free from the mechanical problems associated with conventional apparatus. The proposed inclined plates extractor-separator was operated in batch mode under various operating conditions to evaluate its performance on the basis of extraction efficiency. Water (light phase) was used as solvent to extract ethyl acetate from a heavy phase pool of tetrachloroethylene and ethyl acetate. The ethyl acetate content was analysed using chromatography. A hydrodynamic study was carried out using high speed photography to understand the mechanisms occurring during mass transfer across the two phases. Furthermore, it was found that the proposed inclined plate extractor-separator reduces the overall operating time by 67% and consumes only 13% of the power in comparison to a mixer-settler. A hydraulic power consumption comparison with a mixer settler and a gullwing extractor-separator is also presented. http://www.mdpi.com/1996-1073/2/4/957/ Tue, 27 Oct 2009 00:00:00 CET Energies 2009-10-27 2 4 Article 957 975 1996-1073 Development of an Inclined Plate Extractor-Separator for Immiscible Liquids 2009-10-27 doi: 10.3390/en20400957 Shahid Munir Syed Sheraz Daood Syed Zahoor ul Hassan Rizvi Muhammad Arif Butt http://www.mdpi.com/1996-1073/2/3/556/ A review was conducted on the use of thermochemical biomass gasification for producing biofuels, biopower and chemicals. The upstream processes for gasification are similar to other biomass processing methods. However, challenges remain in the gasification and downstream processing for viable commercial applications. The challenges with gasification are to understand the effects of operating conditions on gasification reactions for reliably predicting and optimizing the product compositions, and for obtaining maximal efficiencies. Product gases can be converted to biofuels and chemicals such as Fischer-Tropsch fuels, green gasoline, hydrogen, dimethyl ether, ethanol, methanol, and higher alcohols. Processes and challenges for these conversions are also summarized. http://www.mdpi.com/1996-1073/2/3/556/ Tue, 21 Jul 2009 00:00:00 CEST Energies 2009-07-21 2 3 Review 556 581 1996-1073 Thermochemical Biomass Gasification: A Review of the Current Status of the Technology 2009-07-21 doi: 10.3390/en20300556 Ajay Kumar David D. Jones Milford A. Hanna http://www.mdpi.com/1996-1073/2/2/445/ The reported patent-pending system comprises a novel biohydrogen reactor with a gravity settler for decoupling of SRT from HRT. The biohydrogenator was operated for 100 days at 37 °C, hydraulic retention time 8 h and solids retention time ranging from 2.2–2.5 days. The feed was a corn-syrup waste generated as a byproduct from an industrial facility for bioethanol production located in southwestern Ontario, Canada. The system was initially started up with a synthetic feed containing glucose at concentration of 8 g/L and other essential inorganics. Anaerobicaly-digested sludge from the St. Mary’s wastewater treatment plant (St. Mary, Ontario, Canada) was used as the seed, and was heat treated at 70 °C for 30 min to inhibit methanogens. After 10 days, when the hydrogen production was steady, the corn-syrup waste was introduced to the system. Glucose was the main constituent in the corn-syrup; its concentration was varied over a period of 90 days from 8 to 25 g/L. The change in glucose concentration was used to study the impact of variable organic loading on the stability of hydrogen production in the biohydrogenator. Hydrogen production rate increased from 10 L H2/L·d to 34 L H2/L·d with the increase of organic loading rate (OLR) from 26 to 81 gCOD/L·d, while a maximum hydrogen yield of 430 mL H2/gCOD was achieved in the system with an overall average of 385 mL H2/gCOD. http://www.mdpi.com/1996-1073/2/2/445/ Wed, 24 Jun 2009 00:00:00 CEST Energies 2009-06-24 2 2 Article 445 455 1996-1073 Biological Hydrogen Production from Corn-Syrup Waste Using a Novel System 2009-06-24 doi: 10.3390/en20200445 Hisham Hafez George Nakhla Hesham El Naggar http://www.mdpi.com/1996-1073/2/2/226/ Anaerobic digestion is an optimal way to treat organic waste matter, resulting in biogas and residue. Utilization of the residue as a crop fertilizer should enhance crop yield and soil fertility, promoting closure of the global energy and nutrient cycles. Consequently, the requirement for production of inorganic fertilizers will decrease, in turn saving significant amounts of energy, reducing greenhouse gas emissions to the atmosphere, and indirectly leading to global economic benefits. However, application of this residue to agricultural land requires careful monitoring to detect amendments in soil quality at the early stages. http://www.mdpi.com/1996-1073/2/2/226/ Thu, 16 Apr 2009 00:00:00 CEST Energies 2009-04-16 2 2 Review 226 242 1996-1073 Closing the Global Energy and Nutrient Cycles through Application of Biogas Residue to Agricultural Land – Potential Benefits and Drawback 2009-04-16 doi: 10.3390/en20200226 Veronica Arthurson http://www.mdpi.com/1996-1073/2/1/48/ Terrestrial transport biofuels differ in their ability to replace fossil fuels. When both the conversion of solar energy into biomass and the life cycle inputs of fossil fuels are considered, ethanol from sugarcane and biodiesel from palm oil do relatively well, if compared with ethanol from corn, sugar beet or wheat and biodiesel from rapeseed. When terrestrial biofuels are to replace mineral oil-derived transport fuels, large areas of good agricultural land are needed: about 5x108 ha in the case of biofuels from sugarcane or oil palm, and at least 1.8-3.6x109 ha in the case of ethanol from wheat, corn or sugar beet, as produced in industrialized countries. Biofuels from microalgae which are commercially produced with current technologies do not appear to outperform terrestrial plants such as sugarcane in their ability to displace fossil fuels. Whether they will able to do so on a commercial scale in the future, is uncertain. http://www.mdpi.com/1996-1073/2/1/48/ Thu, 19 Feb 2009 00:00:00 CET Energies 2009-02-19 2 1 Article 48 56 1996-1073 Microalgal and Terrestrial Transport Biofuels to Displace Fossil Fuels 2009-02-19 doi: 10.3390/en20100048 Lucas Reijnders http://www.mdpi.com/1996-1073/1/2/79/ The production of biodiesel from low-cost raw materials which generally contain high amounts of free fatty acids (FFAs) is a valuable alternative that would make their production costs more competitive than petroleum-derived fuel. Currently, the production of biodiesel from this kind of raw materials comprises a two-stage process, which requires an initial acid-catalyzed esterification of the FFA, followed by a basecatalyzed transesterification of the triglycerides. Commonly, the acid H2SO4 is the catalyst on the first step of this process. It must be said, however, that major drawbacks such as substantial reactor corrosion and the great generation of wastes, including the salts formed due to neutralization of the mineral acid, are negative and virtually unsurmountable aspects of this protocol. In this paper, tin(II) chloride dihydrate (SnCl2·2H2O), an inexpensive Lewis acid, was evaluated as catalyst on the ethanolysis of oleic acid, which is the major component of several fat and vegetable oils feedstocks. Tin chloride efficiently promoted the conversion of oleic acid into ethyl oleate in ethanol solution and in soybean oil samples, under mild reaction conditions. The SnCl2 catalyst was shown to be as active as the mineral acid H2SO4. Its use has relevant advantages in comparison to mineral acids catalysts, such as less corrosion of the reactors and as well as avoiding the unnecessary neutralization of products. Herein, the effect of the principal parameters of reaction on the yield and rate of ethyl oleate production has been investigated. Kinetic measurements revealed that the esterification of oleic acid catalyzed by SnCl2·2H2O is first-order in relation to both FFAs and catalyst concentration. Experimentally, it was verified that the energy of activation of the esterification reaction of oleic acid catalyzed by SnCl2 was very close those reported for H2SO4. http://www.mdpi.com/1996-1073/1/2/79/ Wed, 24 Sep 2008 00:00:00 CEST Energies 2008-09-24 1 2 Article 79 92 1996-1073 Esterification of Oleic Acid for Biodiesel Production Catalyzed by SnCl2: A Kinetic Investigation 2008-09-24 doi: 10.3390/en1020079 Abiney L. Cardoso Soraia Cristina Gonzaga Neves Marcio J. da Silva http://www.mdpi.com/1996-1073/1/2/41/ The rapidly growing world population and rising consumption of biofuels are increasing demand for both food and biofuels. This exaggerates both food and fuel shortages. Using food crops such as corn grain to produce ethanol raises major nutritional and ethical concerns. Nearly 60% of humans in the world are currently malnourished, so the need for grains and other basic foods is critical. Growing crops for fuel squanders land, water and energy resources vital for the production of food for human consumption. Using corn for ethanol increases the price of U.S. beef, chicken, pork, eggs, breads, cereals, and milk more than 10% to 30%. http://www.mdpi.com/1996-1073/1/2/41/ Tue, 16 Sep 2008 00:00:00 CEST Energies 2008-09-16 1 2 Review 41 78 1996-1073 Biofuel Impacts on World Food Supply: Use of Fossil Fuel, Land and Water Resources 2008-09-16 doi: 10.3390/en1010041 David Pimentel Alison Marklein Megan A. Toth Marissa Karpoff Gillian S. Paul Robert McCormack Joanna Kyriazis Tim Krueger http://www.mdpi.com/1996-1073/1/1/3/ As crude oil price reach a new high, the need for developing alternate fuels has become acute. Alternate fuels should be economically attractive in order to compete with currently used fossil fuels. In this work, biodiesel (ethyl ester) was prepared from waste cooking oil collected from a local restaurant in Halifax, Nova Scotia, Canada. Ethyl alcohol with sodium hydroxide as a catalyst was used for the transesterification process. The fatty acid composition of the final biodiesel esters was determined by gas chromatography. The biodiesel was characterized by its physical and fuel properties including density, viscosity, acid value, flash point, cloud point, pour point, cetane index, water and sediment content, total and free glycerin content, diglycerides and monoglycerides, phosphorus content and sulfur content according to ASTM standards. The viscosity of the biodiesel ethyl ester was found to be 5.03 mm2/sec at 40oC. The viscosity of waste cooking oil measured in room temperature (at 21° C) was 72 mm2/sec. From the tests, the flash point was found to be 164oC, the phosphorous content was 2 ppm, those of calcium and magnesium were 1 ppm combined, water and sediment was 0 %, sulfur content was 2 ppm, total acid number was 0.29 mgKOH/g, cetane index was 61, cloud point was -1oC and pour point was -16oC. Production of biodiesel from waste cooking oils for diesel substitute is particularly important because of the decreasing trend of economical oil reserves, environmental problems caused due to fossil fuel use and the high price of petroleum products in the international market. http://www.mdpi.com/1996-1073/1/1/3/ Thu, 10 Apr 2008 00:00:00 CEST Energies 2008-04-10 1 1 Article 3 18 1996-1073 Waste Cooking Oil as an Alternate Feedstock for Biodiesel Production 2008-04-10 doi: 10.3390/en1010003 Arjun B. Chhetri K. Chris Watts M. Rafiqul Islam