The current problem is so severe that an alternative fuel will help. The potential issues coming from Algae generated hydrogen fuel may be just 1 among all. The storage of hydrogen fuel is very important that we can't ignore. We don't want to see a hydrogen bomb ignition whenever there is a car accident somewhere.
We may end up in a "the devil you know..." situation.
Petroleum is ultimately limited and takes long stored carbon and puts it in the air. Hydro hard fish runs. Wind harms bird migration and may do other things we haven't discovered yet. I'm sure there are some unintended consequences with tide based generation. Nuclear, is, well.. nuclear. Hydrogen today is largely produced from fossil fuels. Algae-based hydrogen production may cause an invasive species invasion like none before it. Ethanol may lead to the decimation of food staples.
Okay, maybe we'll end up in a "the devil we know isn't workable and neither are any of the devils we don't know."
Energy production using algae without the need for exotic materials should be feasible - after all, the algae seem to be managing the process for themselves without importing special materials. It certainly is necessary to ensure that the energy production is contained and does not adversely impact natural habitats. Maybe as a bonus, the "energy farms" will be able to produce food with their excess biomass.
If only I knew :-) Hydrogen fuel cells are promising but we have to find a cheap way of mass producing hydrogen. Solar is great but the economics are still stuck up against it despite what we hear from its protagonists. Ethanol has zero-carbon advantage but if harnessed at a mass scale, food shortages would occur. Nuclear has major security concerns. Wind and wave energy sources are not available everywhere. Perhaps we need a mix of these technologies at least for the forseeable future.