when I worked at ORNL I was involved with a DOT project investigating using vanadium dioxide ceramic thermoelectrics on engines. Basically you could run no coolant and have the waste heat converted to electricity by exploiting a vanadium phase transition, it got published - John Fairbanks was the principal investigator
Looked at a few ways to do it, in the exhaust was most efficient cuz it's alot of the heat, and in diesels it can go in the EGR.
Coolant and exhaust waste heat is responsible for like twothirds of the energy of gas. that sucks!
In the end it was decided to be too expensive for most vehicles, pay back was like 600k miles, but for trucks that's pretty achievable, just too long to be worth it. It did get some attention for cabin cooling though since AC takes a shitload of energy and if you can do it without refrigerant that is a big deal for emissions. depending on polarity you can heat or cool. cool!
I think its still active though looking at how to use the same thermoelectrics to cool down batteries and recover waste heat there. much more direct use
Anyway, it's expensive, but can work, if you have a draw for it. For the temps on a cylinder vs ambient the efficiency isn't great and you'd probably have to have it go to a resistor and just be a heat dump radiator anyway cuz it's probably more power than all the stuff on the bike can use