Large-scale biofuels

There exists a link between developed and rural areas for biofuels production. Large-scale biofuels activities in developed countries may reduce the export of food products, pushing the prices of these goods up. This would in turn positively affect mral areas in developing countries benefitting of higher net surpluses in food... 

Typically, large scale processes are dominated by the cost of raw materials and the downstream processes are usually well understood. However, the treatment of effluent is a significant problem and can make an appreciable contribution to the cost of production. Surplus biomass, spent slurry, and either utilisation or disposal of feed residues represent problems that must be solved economically. This is the major problem associated with the production of biofuels. 

Wood powder is a kind of upgraded fuel that is burned in large-scale combustion plants for heat production. However, it is possible to use wood powder for power generation as well. It is a biofuel made of sawdust, shavings and bark. The raw material is crushed, dried and milled to tine particles in order to obtain the best fuel properties. There are many different wood powder qualities dependant on different physical properties such as particle size distribution, particle shape and also moisture content. The powder is usually handled in a closed system from milling to storing in silos to avoid the risk of dust explosions. The raw materials and type of mill used determine the properties of the wood powder (Paulrud et al, 2002). 

Ethanol is the most successful biofuel and, for example, already supplies 40% of Brazil s transportation fuel needs. Its main advantage is that there is a well-established infrastructure for its production and use. Techniques for its production by the fermentation of sucrose are in place, large-scale distillation technologies have been developed, and it can be used in so-called flexible-fuel vehicles. In addition, the logistics for its distribution are well-established. Every gas station in Brazil supplies it, with gasoline being provided in a commercial blend containing up to 24% ethanol. 

In the biofuels arena, the energy efficiencies of microwave and conventional heating have been compared in the preparation of biodiesel. To be viable, biodiesel production must be conducted on a very large scale and also must be energy efficient over the entire process. Calculations indicate that while microwave heating in batch... 

It is useful to consider two major forms of biomass fuel mechanically processed and chemically processed. For mechanically processed biofuel in which the material is used essentially in its natural form (as harvested) direct combustion usually supplies heat for cooking, space heating or electricity production, although there are also small- and large-scale industrial applications for steam raising and other processes requiring low-to-medium temperature process heat. 

Over the last decade, mounting pressure on crude oil prices together with a desire to move to more sustainable processes pushed many companies to use the fermentation technology even for the synthesis of bulk chemicals. The large-scale productions of lactic acid for polymers and of ethanol as biofuel are two recent examples of this trend. 

In large-scale applications, fiuidized-bed boilers are now dominant on the market. Both bubbling fluidized beds (BFBs) and circulating fluidized beds (CFBs) are used for biofuel firing. BFBs were originally limited to a rather narrow specification of fuels but now flue-gas recycling is used in both types of boilers. Especially, CFBs are considered... 

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