Fuels are a unique category of chemicals. They are produced in volumes at least ten times higher than other chemicals and are measured by very different standards. For most industrial chemicals, purity is the key measure of the chemical’s quality. Fuels are different: the composition of the fuel is irrelevant provided that the mixture meets a stringent set of requirements. For gasoline, some of these requirements are properties of the blend, such as octane rating and vapor pressure. Others are compositional, like sulfur and benzene content. The most important point, however, is that it does not matter how the specifications are reached, as long as all of them are met.
The differences between chemicals and fuels have important implications for next generation technologies such as biofuel production. Processes that selectively produce a single compound, such as ethanol, are unnecessary, since a blend of different species may have better performance than a single component alone. Instead, the focus of new fuel technologies should be on material and energy efficiency, resistance to poisons and feed impurities, and cost.
At Exelus, we believe that the long-term success of biofuels is dependent on the development of an efficient technology that can convert non-food, lignocellulosic biomass like grass, straw, wood, and agricultural wastes into fuels. Furthermore, the fuel product should be compatible with the existing infrastructure and engine technology and low cost. Biofuels technologies are subject to the same market forces as conventional petroleum products – price matters! Low cost, simple and robust operation, and a high quality fuel product are the cornerstones of a successful technology.
Biological and enzyme-based reactions are too slow to produce the quantities of fuel consumed every day around the world. High temperature routes like gasification suffer from intrinsic limitations owing to the equilibrium-limited endothermic reactions that make up these technologies. Only a process that more closely resembles conventional refining – operating a moderate temperatures and short reaction times – is capable of producing biofuel at cost low enough to gain market acceptance.
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