There is a much more efficient way to deal with point sources, if you have a clean energy source in their neighborhood: just shut them down and replace the energy they provide with the clean energy you would use to scrub the CO2 from the air.
Yes, sometimes this is practicable. But many locations do not have sufficient renewable energy available, and nuclear has become unpalatable for a variety of reasons.
Scrubbing CO2 from boiler or turbine exhaust takes a small fraction (5%-ish) of the energy needed to convert it into fuel. If the source is a power plant, the CO2 can be captured at a cost of efficiency penalty of around 10%.
Once it is captured, storing and transporting CO2 to a location with abundant clean energy is also relatively simple.
