Synthetic biofuels

The role of biocomponents in traffic fuel is increasing. The European Union Directive [1] on the promotion of the use of biofuels for transport purposes states that by the end 2005 traffic fuels should have contained 2% of components produced from renewables. The figure rises to 5.75% by the end of 2010 and up to 20% by the end of 2020. This directive defines biofuel as a liquid or gaseous fuel for transport produced from biomass, biodiesel as a methyl ester produced from vegetable or animal oil, of diesel quality, to be used as biofuel and synthetic biofuel as synthetic hydrocarbons or mixtures of synthetic hydrocarbons, which have been produced from biomass. The European Commission also encourages member states to lower tax rates on pure and/or blended biofuels, to the offset cost premium over petroleum-based fuels [1, 2]. 

Bond-Watts BB, BeUerose RJ, Chang MCY. (2011). Enzyme mechanism as a kinetic control element for designing synthetic biofuel pathways. Nat Chem Biol, 7, 222-227. 

Giiell, B.M., Bugge, M., Kempegowda, R.S., George, A., Paap, S.M., 2012. Benchmark of Conversion and Production Technologies for Synthetic Biofuels for Aviation (SINTEF Energy report prepared for Avinor). 

Biofuels. Biofuels are Hquid fuels, primarily used ia transportation (qv), produced from biomass feedstocks. Identified Hquid fuels and blending components iaclude ethanol (qv), methanol (qv), and the ethers ethyl /-butyl ether (ETBE) and methyl /-butyl ether (MTBE), as well as synthetic gasoline, diesel, and jet fuels. 

At the heart of the book stands the question of how the growing energy demand in the transport sector can be met in the long term, when conventional (easy) oil will be running out. Among the principal options are unconventional oil from oil sands or oil shale, synthetic Fischer-Tropsch fuels on the basis of gas or coal, biofuels,... 

Second-generation biofuel technologies make use of a much wider range of biomass feedstock (e.g., forest residues, biomass waste, wood, woodchips, grasses and short rotation crops, etc.) for the production of ethanol biofuels based on the fermentation of lignocellulosic material, while other routes include thermo-chemical processes such as biomass gasification followed by a transformation from gas to liquid (e.g., synthesis) to obtain synthetic fuels similar to diesel. The conversion processes for these routes have been available for decades, but none of them have yet reached a high scale commercial level. 

Today ethanol and biodiesel (FAME) are the most common biofuels. Alternative fuels from fossil energy sources are mainly LPG and CNG. Synthetic gasoline and diesel from coal (CTL) and natural gas (GTL) are produced mainly in South Africa. Electricity used in battery-electric vehicles plays a minor role today. The fuel consumption for road transport in the world today amounts to about 65 700 PJ per year (IEA, 2006a) in total, the share of alternative fuels for transport at the time of writing was about 2.7% (Table 7.24). 

The alternative fuels and drive systems available only seem to be viable on the mass market, if the oil price stays above 60 to 70 /bbl for a sustained period. Oil prices peaked above 140 /bbl in summer 2008 and many experts believe that stable oil prices over 100 /bbl could be reached in the next one or two decades. The higher the market prices of fossil fuels, the more competitive low-carbon alternatives will become The principal choice here is between biofuels, electricity and hydrogen, provided that they are produced either from low/zero-carbon feedstock or that the C02 generated during their production is captured and stored. But higher priced conventional oil resources, on the other hand, can also be replaced by high-carbon alternatives such as oil sands, oil shale or synthetic fuels from coal and gas. 

These are the touchstones for all alternative fuels, which - along with hydrogen -include biofuels, compressed natural gas (CNG), and synthetic liquid fuels derived from natural gas (NG) and coal. Although this chapter focuses on hydrogen, it is relevant to recognize that this whole spectrum of future fuels will in the de-... 

Bioelectrocatalysis involves the coupling of redox enzymes with electrochemical reactions [44]. Thus, oxidizing enzymes can be incorporated into redox systems applied in bioreactors, biosensors and biofuel cells. While biosensors and enzyme electrodes are not synthetic systems, they are, essentially, biocatalytic in nature (Scheme 3.5) and are therefore worthy of mention here. Oxidases are frequently used as the biological agent in biosensors, in combinations designed to detect specific target molecules. Enzyme electrodes are possibly one of the more common applications of oxidase biocatalysts. Enzymes such as glucose oxidase or cholesterol oxidase can be combined with a peroxidase such as horseradish peroxidase. 

We thank Dr. J. A. Hyatt for the gift of synthetic phenyltetramers and Max Haney for helpful discussions. This work was funded by the Biochemical Conversion Program at the DOE Biofuels and Municipal Waste Technology Division through FTP No. 658. 

Since late 2007, the Energy Biosciences Institute in Berkeley has been the center for cooperation between scientists from the University of California and the Agricultural Department of the University of Illinois for the production of fuels from so-called energy crops like switch grass. In this second-generation biofuel project that is financed over a 10-year period with 500 million by oil company BP, biomass is converted with the help of synthetic catalysts, for example, organometallic compounds, in a special solvent medium, better known as ionic liquids, into hydrocarbons with properties close to automotive fuels. 

Algae s potential as a source of biofuel got a big boost from an unlikely source in 2009. ExxonMobil announced plans to invest 300 million or more in San Diego, California-based Synthetic Genomics, a company headed by genome pioneer Craig Venter. 

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