This morning I was thinking about how much heat an automotive engine produces, which is just pumped uselessly out into the air through the radiator. It seems to me that there must be some way to make use of that excess heat to run some sort of electrical generator and charge a battery or something, gaining value at a negligible cost in gas mileage. I’m sure other people have thought of this, but I haven’t been able to find anything that they’ve done in this area that’s actually practical. If you know about anything like that, please let me know.