I bet even as an animal feed supplement it makes more sense than making fuel. We have connected the dots between feed and healthiness of fish and eggs. For ungulates I understand you have to beware of high protein. Unrestricted access to clover (which is one of the most palatable things they can eat) can make them quite sick. An algae/clover blend could probably still be palatable, and if you selected for high fat to protein ratio in the algae it might actually be safer.

As someone once put it, “oil is so plentiful we can afford to set it on fire”. Finding something else we can set on fire will be difficult, but it might be better to pyrolyze it directly and feed electricity into the power grid. The waste heat from the heat engine could be used in a heat exchanger to dry the algae before firing.

Speaking of power, the cooling effect of photosynthesis is also an underexplored areas.