That's why some scientists have looked to seaweed as a feedstock. Kelp is particularly attractive, in that it's abundant and grows extremely quickly, although its fuel yields haven't been particularly impressive. That could be about to change, however, thanks to a newly-developed hydrothermal process.
Khanh-Quang Tran, an associate professor at the Norwegian University of Science and Technology (NTNU), has been experimenting with heating kelp very quickly. More specifically, Tran and his team put a slurry of kelp biomass and water in sealed drinking-straw-like vessels known as quartz capillary reactors, then heated those reactors to 350º C (662º F) at a rate of 585º C (1,085º F) per minute, and held them at that temperature for 15 minutes.
A variation on a process known as hydrothermal liquefaction, the technique resulted in 79 percent of the biomass being converted into bio-oil. A previous UK study also explored the hydrothermal liquefaction of the same type of kelp (Laminaria saccharina), although it didn't incorporate the rapid heating aspect. In that case, the yield was only 19 percent and the oil was harder to refine, plus the addition of a chemical catalyst was required. No catalyst is necessary with the NTNU system.