Diesel-generated electrical propulsion in ships have been a thing for a long time. You can use several generators and only fire up the ones you need for the pow

Diesel-generated electrical propulsion in ships have been a thing for a long time. You can use several generators and only fire up the ones you need for the power you need and the ones running can do so in or near their optimal efficiency zones. You can also do away with the weight and mechanical losses from gear boxes because the electric motors don't need them.