Why not use green tech from the outset?
Really no good reason not to at this point. Its demonstrably beneficial from less pollution to lower overall emissions, and builds up a "next gen" of expertise that will be extremely valuable over the next century, whoever gets these investments done will be in a great place over the next century relative to those who are later to the game, and that expertise will be very valuable (and a huge engine for economic growth).
Go where the puck is moving, not where it is.