That's not how that works. Rust can actually make power usage worse because it generates larger code sizes which causes more I-cache churn and thus more power usage. Making efficient use of caches, power states, and reducing polling are all things that you don't just get for free because "I'm using Rust and Rust is efficient". Rust lets you write something efficient after you've spent tons of time working on making it efficient and understanding how power is consumed on a particular platform for a particular app.

Once again, you could just use a language where they do this for you in the runtime instead of trying to reinvent (probably poorly) these ideas yourself.