Biofuels (Butanol-Ethanol Production)
Petroleum-based motor fuels generally consist of hydrocarbons or hydrocarbon fragments. This chemical functionality provides the fuel with a high energy density and a relatively low boiling point, viscosity, and vapor pressure. The premium petroleum fuels are isooctane and hexadecane for spark ignition and diesel engines, respectively. Conventional biofuels differ chemically, but new biofuels that are currently under development more resemble their petroleum counterparts. Current biofuels are principally ethanol and alkanoic acid methyl esters, or biodiesel. The next generation of biofuels will likely have a higher proportion of hydrocarbon fragments than ethanol. These include higher alcohols, ethers, alkanes, and alkenes.