Yes stoves rank right up there with dryers in terms of huge energy users. So that is probably very inefficient, to use a stove to vaporize water. It would probably save a ton of money to use an actual vaporizer which is designed to do that. Or just leave pots of water lying around
Plants are great. They actively give water out into the atmosphere over time. You do have to water the plants of course
Also, don't use a dryer! Hang your wet clothes around the house. That is a great natural humidifier and will save you tons of money by not running the dryer.