Biofuels biogas

Bioreactors are typically considered vessels that produce products in a controlled manner via biological conversion. These systems convert materials (substrates) by influencing metabolic pathways to transform materials into products of interest (Williams 2002). Microbial bioreactors have been used for many years to produce products such as cheese, wine, beer, and bread through traditional fermentation, a process that was studied in depth by the famous microbiologist Louis Pasteur. Current technologies not only produce these products, but also a variety of other products such as industrial solvents (biofuels), biogas, acids, sugars, vitamins, antibiotics, and enzymes for bioconversion processes, as well as other primary and secondary metabolites (Williams 2(X)2 Ullmann 2007). 

Fig. 5.6 C02-savings by use of biofuels made from energy crops according to Schmitz (2003), Quirin et al. (2004), CONCAWE (2006), Hill (2007) and BMELV (2007b). Conversion pathways 1 Straight oil —> Drive 2 Biodiesel —> Drive 3 Grain —> Heat 4 Ethanol —> Drive 5 Ethanol —> Heat Power 6 Ethanol —> Drive 7 Bales —> Heat Power 8 BtL —> Drive 9 Methanol —> Drive 10 Ethanol —> Drive 11 Biogas —> Drive 12 Biogas —> Heat Power 13 Chips — Heat 14 Chips —> Heat Power 15 BtL —> Drive...

Biofuel Fuel derived from organic sources, e.g., biogas, biomass and the biodegradable fraction of waste. The use of biofuel is neutral in terms of carbon dioxide emissions. 

In Turkey, Romania and Bulgaria, biomass could be used for the production and export of biofuels or biogas, for local heating or decentralised electricity generation. 

We may differentiate between direct conversion of biomass into bioenergy (electricity and heat, solid fuels from biogenic wastes and residues, biogas, etc.) and biofuels. Catalysis has a minor role in the first case but is a critical element in the production of biofuels. However, notably, there are also potentially interesting developments related to bioenergy. 

Notably, several types of liquid biofuels exist or are under development and have the potential to replace fossil fuels, especially in the transportation sector. The focus is on organic fuels such as ethanol, butanol, methanol and their derivatives ETBE, MTBE, which can be produced by fermentation, but also biodiesel and liquid biogas, which can provide interesting biomass-based alternatives to diesel and LPG. 

First generation biofuels Sugar, starch, vegetable oils, or animal fats Bioalcohols, vegetable oil. Biodiesel, biosyngas, biogas... 

Based on this ability to manipulate the algal composition, these organisms can be used for the production of different types of biofuel. For example, those algae which are rich in hpids are better suited for the production of bio-oil or biodiesel those rich in starch can be used for alcoholic fermentations to afford ethanol and those rich in proteins and starch can be used for the production of biogas. 

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

Figure 5.6. Historic trends in the world s gross energy use and its distribution on sources. During the early years, food energy includes an estimate of the draft animal power utilised. Wood includes straw and biofuels ethanol and biogas (updated from Jensen and Sorensen, 1984, with use of USDoE, 2003, and Sorensen, 2004a).

For bio-energy resources, residues from households and food industry are available year roimd, and fresh biomass, whether harvested or collected, can usually be stored, so that conversion may take place at a time convenient for the conversion capacity or desirable from the point of view of users. The scenario use of biomass is primarily for production of biogas, liquid biofuels such as methanol or eventually hydrogen. 

Another example regards an aspect discussed before on the sustainability of land use for biofuels. We have already remarked the various problems in this analysis that can be summarized, in a simplified form, in reply to the question which use is the most sustainable for one ha of land. There are different possible options to produce (i) bioliquids (by fast pyrolysis), bioethanol or biodiesel, (ii) food, (iii) chemicals, (iv) electricity or (v) to feed animals. There are more options (e.g., biogas) but the present already allow a good comparison, although theoretical (land productivity depends on several factors and, for example, palms to produce the vegetable oil raw material for biodiesel is not locally in competition with the production of bioethanol from biomasses for which different climate and land characteristics are required). 

The spread of biofuels has increased the applications of the double fuel burners, where a traditional fuel (for example gas) is used as a backup in case of a lack of the renewable resource. Use of bio-oil and biogas increased reliability problems on some specific burner components like pumps and valves. 

Figure 4. Energy production in the form of biofuels (straw and biogas), metabolisable energy in crops and fossil energy use for crop production ...

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