Lots of people with a Snowberry, possibly one of the top selling sailable warship kits ever, many have fitted smoke units. So far, the water ones that I have seen have been on the large size for that size of boat, and I am not sure that they require any less energy to produce a given amount of vapour than an oil evaporator, but I stand to be corrected.
Using a generator runs into the law of conservation of energy, you cannot have a perpetual motion machine. Any generator would need a different source of power to the battery to provide the energy to produce the vapour. I remember "rotary converters", which were a way of getting a (usually higher) DC voltage from a battery. They were hideously inefficient. The simplest way to get a nice smoke plume, cutting out all of the energy conversions, is an insulated brass tube containing a smouldering joss stick bundle.