There was an interesting question raised at a forum I read recently : "If the theoretical maximum photosynthetic conversion efficiency is only 11% (of solar energy), and if solar cells theoretically have much higher (research has shown over 40%) conversion efficiency, why bother with algae?". To that, a person answered that this was because solar energy cannot make liquid fuels while algae can. This answer sounds correct, but in my opinion is not. It is not difficult to see that the electricity from solar panels can be used to heat biomass to produce syngas which can be turned into liquid fuels.
I would think the real answer to that question has to do with yields. Whatever method you use to get liquid fuels, unless you use algae, you do not have enough biomass to produce liquid fuels, period. So that I think is the real reason why the algae route should be tried in all earnest