No, you are not missing anything. I designed this to come into play after electric engines are researched, or a bit later, about the time the player is in the middle of setting up productivity science. I did consider using just regular engines during the design and testing, but found that the electrical power generated was just not enough to support a robust pollution scrubbing. Based on my experience, there are way to many competing issues, in the early mid game, when the player is trying to set up oil, trains, plastic, and advanced circuits.
Hiladdar