One possible feedstock for biofuel production is algae, which could be grown and processed in various ways, producing transportation fuels. Some people seem to think this is the most plausible path to affordable non-fossil transportation fuels. Others think various land-based plants and processes (cellulosic ethanol, jatropha, etc) are more viable. Another big question is how cheap biofuels could ever become. Biofuels at $100 per barrel probably wouldn’t mean the end of air travel, private cars fueled by liquid hydrocarbons, etc. Biofuels at $1,000 a barrel would push us a lot father away from their mainstream use.
I don’t know enough to decide one way or the other, though it certainly doesn’t seem like anyone is making cheap and functional biofuels from algae right now.