I would go to March 1886, Great Barrington, Massachusetts, and I would seek out William Stanley Jr.
Stanley had already built the first practical transformer and was demonstrating a complete high voltage AC transmission system. In 1886, his system transmitted electricity along Main Street and stepped it down for individual businesses. This was one of the critical technological foundations of the modern electric grid.
From there, I give him the conceptual roadmap for the electrical civilization that follows his work. I know enough about how modern renewables work to give him some good ideas. Oh and involving Westinghouse would be important and pretty much inevitable. This would be easier if I could prepare like, a binder, but I could still potentially help with just what I happen to know.
The goal is to go back when petrochemicals as an industry were still weak enough to be slain. If I were successful it would be one of the most outsized positive impacts I could have on the course of human history.
Yeah but humanity used a LOT of coal and oil already. I think making electricity ubiquitous would be a better idea. I want to abort big oil as an industry before it can be conceived.
Midgley is a person sitting on top of a technological trajectory, not the trajectory itself.
Even if Midgley never existed, someone else was probably going to pursue antiknock additives, leaded gasoline, refrigeration chemistry, etc. You might prevent Midgley’s particular disasters, but you haven’t fundamentally altered the industrial system that makes them attractive. You gotta do that or someone else is just gonna figure it out.
Eliminating Midgley is too narrow compared with changing the economics of energy.
Coal was already an enormous industrial fuel before Midgley was born. Oil was already becoming important.