The amount of CO2 produced in power plants is in the order of tons, so you will require enormous green houses that will only utilize ~1500ppm saturated air. The earth as a massive greenhouse cannot even coupe with the load so how will a greenhouse?
CO2 capturing as indicated in the flow scheme is also quite expensive (but doable)! At this stage the only viable option for the CO2 seems to be sequestration (pumping the CO2 deep into the earth to be physically and chemically absorbed into the mineral deposits and rocks). South Africa does not seem to have perfectly suited locations for sequestration though...
I investigated a similar idea that is proposed in this thread some years ago. Using mutated algae or CO2 fixing bacteria, but the scale of things were just impractical...