50 000 000 hectares

Only half the size of south Australia (approx 100 000 sq kilometres)

So not that much really....

now I know I didn't calculate ongoing emissions. But there are alot of other techniques. We don't have to rely on just sequestering algae..

There are a "few" logistical/technical/economic issues with producing that much algae. But there is alot of non-ariable land out there... and if your just dumping it in the ocean the algae could be transported as sludge.

I wonder what the economic issues are?