Your question makes it simple to ask when using the parameters given. "Regardless of cost" is the part I will address.
If it is too expensive to build it must stand to reason the benefits of production won't be recovered and so the impact makes it too inefficient. Like trying to heat a football stadium with an open flame. I believe many things are possible but not necessarily feasible.
We have a very effective and Earth conscious way of cleaning the air that has been around forever that also id not being used as it should be. Plant and raises TREES ! Quit burning the rain forests and halt production of pollutants that are exhausted into the air causing all the problem. That isn't gonna happen either though.
So long as corporations are a for profit entity there will rarely be an emphasis on what is proper over profit.