A greening initiative at Red Hook’s waterfront is ready to set sail, but some local activists see the Port Authority as slow to get on board. The agency, which owns the piers between Atlantic Avenue and Red Hook, says it is looking into installing the infrastructure required to allow for a process called cold ironing — which helps reduce likely carcinogenic emissions from docked ships — but only at Pier 12, the passenger cruise ship terminal. That’s because there are far more incoming cargo vessels than cruise ships, making the initiative more complex to implement in other terminals, said a spokesperson for the Port Authority. But others say cargo vessels would actually be easier and cheaper to retrofit with the greening equipment, and Community Board 6 is behind the efforts of port operator American Stovedoring International to move ahead with cold ironing outfitting despite the Port Authority’s resistance. Last week, the board unanimously approved the installation of the infrastructure at Piers 8, 9 and 10, saying that the move could have tremendous health benefits for the neighborhood.