Its biotechnological "solutions" are just nonsense.
no, because they are outside organic agricultural areas which they are nonsense, because how much plant or straw is thrown to make grains of wheat or corn or rice !!
We can cultivate algae, or others, in the sea, on deserts etc, outside any agricultural surface and recover all the carbonaceous mass for fuel !!
In any case, we are forced to renew the oxygen (which in photosynthesis comes from water), in an amount equal to what is consumed, because otherwise we will lose this oxygen which is in fairly small quantity in the atmosphere (1 / 2000 of oxygen present in the oceans H2O).
Currently we consume too much of this oxygen by producing too much CO2.
On earth there are enough fossil fuels, coal, oil, methane (clatharates), gas, etc. to burn all the oxygen in the atmosphere !!