Butanol can be made from algae or diatoms using only a solar powered biorefinery. This fuel has an energy density 10% less than gasoline, and greater than that of either ethanol or methanol. In most gasoline engines, butanol can be used in place of gasoline with no modifications. In several tests, butanol consumption is similar to that of gasoline, and when blended with gasoline, provides better performance and corrosion resistance than that of ethanol or E85.
The green waste left over from the algae oil extraction can be used to produce butanol. In addition, it has been shown that macroalgae (seaweeds) can be fermented by bacteria of genus Clostridia to butanol and other solvents. Transesterification of seaweed oil (into biodiesel) is also possible with species such as Chaetomorpha linum, Ulva lactuca, and Enteromorpha compressa (Ulva).
The following species are being investigated as suitable species from which to produce ethanol and/or butanol:
* Alaria esculenta
* Laminaria saccharina
* Palmaria palmata