Port of Los Angeles Pollution Reduction Program - Ships Plug In for Powerower -- AMP.
Here is an idea very similar to what trucks use at truck stops while overnighting. Rather than use the diesel engine for power (heat or a/c, etc) they use a smaller auxiliary power source or plug in for their power 
needs.
The Ports of Los Angeles now have the same type of system available ... called Alternative Maritime Power™".
" ... AMP™ ... focuses on reducing emissions from container vessels docked at the Port of Los Angeles. ... AMP-equipped ships “plug in” to shore side electrical power ...."
" ... The Port of Los Angeles is the first Port in the world to use AMP technology for in-service container ships."
" ... currently in discussions with several cruise lines to expand the use of AMP ..."
Wjht is needed to use the AMP technology .. ?
"Components ... include a shore side power source, a conversion process to transform the shore side power voltage to match the vessel power systems, and a container vessel that is fitted with the appropriate technology ..."
" ... estimates are that AMP will reduce NOx by one ton and take more than half a ton of sulfur oxides (SOx) out of the air each day the ship is at berth and plugged in."
Via: PortofLosAngeles Link