The radiators don’t have to increase in size really. If it’s more efficient you don’t have to reject as much heat. But definitely a large increase in complexit

The radiators don’t have to increase in size really. If it’s more efficient you don’t have to reject as much heat. But definitely a large increase in complexity as Stirling engines are mechanical devices and thermoelectrics are solid-state. The Stirling engines can be over 25% efficient rather than like 6% for thermoelectrics. NASA has operated a Stirling engine in a lab for 17 years so it’s feasible, at least.