Biofuel production routes

Indirect production routes via the reforming of the produced biofuels (e.g. biogas, bio-oil) ... 

Promotion of diversification and flexibility of the biofuel agroindustry, considering innovative production routes, alternative feedstocks, and new products. 

Jackson, R. (2007). The BHR Biofuels intensified biodiesel production route. Proceedings of the 15th PIN Meeting, Cranfield University, October. See www.pinetwork.org. 

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. 

Despite these limitations, the eco-efficiency analysis provides a good bases for discussion. Figure 5.8 compares different alternatives, showing that, for example, the use of biomass for electricity production via the conventional combustion route is not different, in terms of eco-efficiency, with respect to biodiesel, while bioethanol is slightly worse. The best situation is for vitamin B2 by fermentation, but clearly the dimension of the market between vitamin B2 and biofuels is completely different. 

In addition to these substantial differences, several barriers currently impede the market entry of renewable resources Predominantly today s chemical industry is orientated towards fossil raw materials and thus the existing processes are incompatible with the new resources. Currently, the use of renewable resources leads to disadvantages in price compared with crude oil. Further, the qualitative and quantitative availability of the natural products hampers a major breakthrough. The supply and the composition of the renewables often change with year and location. Additionally, some renewable resources with special properties, such as palm oil, cannot be cultivated everywhere because of unfavorable climatic conditions and must therefore be imported via long routes. Furthermore, the increasing competition between using crops for food and feed on the one hand and for biofuels on the other hand causes ethical problems. 

Both biomethane production paths complement one another in an ideal way. While the thermo-chemical route focuses on solid biofuels e.g. wood, straw) the bio-chemical route uses wet biomass e.g. animal manure, maize silage). The latter will be realized with plant capacities in the one-digit thermal MW-scale and the former in the two- to three-digit MW-scale. The provided product is basically similar and can be used together with natural gas in any mixture. The erection of the biogas and Bio-SNG conversion plants can be planned directly at the established gas grid. 

Just as the fossil fuel and petrochemicals industries are closely connected, the production of the same but bio-based chemicals will be closely related to the manufacturing of biofuels. The focus of commercialization by using biomass as a feedstock is mainly on ethanol, biodiesel, butanol, hydrogen, Fischer-Tropsch fuels, methanol, methane, and MTBEyETBE (methyl- or ethyl-tert-butylether). These products can be used either as biofuels or chemicals for further converting. In the context of this chapter, only routes for the ethylene and propylene... 

Fig, 4 From waste lipids to biofuels (biodiesel, RME) to PHA biopolymers, including the direct route of PHA production from lipids... 

Economic studies on the production of biobutanol from corn determined that distillation recovery of butanol from the dilute ABE fermentation broth is not economical comparing to the butanol production from the current petrochemical route (Ezeji et al., 2007c). However, the life-cycle analysis on the corn-based butanol production indicated that the use of corn-based butanol as a biofuel can lead to substantial fossil energy savings relative to the use of conventional petroleum gasoline, and it can also avoid a large amount of GHG emission burdens (Wu et al., 2008). 

The modification and adjustment of vegetable oil and animal fat properties for biodiesel production can be developed using methods of transesterification, esterification, microemulsification and cracking (Knothe, 2005 Ranganathan et al., 2008). However, transesterification and esterification reactions have been the most commonly used methods by the biofuel industry as synthetic routes (Figure 1) (Robles-Medina et al., 2009). 

Naik, S. N., V. V. Goud, P. K. Rout, and A. K. Dalai. 2010. Production of First and Second Generation Biofuels A Comprehensive Review. Renewable and Sustainable Energy Reviews 14 (2) 578-597. 

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