Question about UT power generators

[SuedodeuS]

Originally Posted by malloyd

If your ultratech generator is running at 50% efficiency, it's broken.

This sounds good for people comparing it to internal combustion or gas turbines, but a modern steam plant can reasonably hope to do that well, and a fuel cell installation should do better. If you are running a fusion unit, with a hot side temperature of a billion kelvins at 50% thermodynamic efficiency, you might want to add a topping cycle on your half billion kelvin radiator...

50% efficiency is what you'd get with an ideal Carnot heat engine with the hot reservoir (reactor) at 600K and the cold reservoir (outside air) at 300K (room temperature). What's the hottest you can get the internal reaction going at without "leaking" heat to the environment, and still have it fit in a backpack-sized unit? I have no idea, but I don't think it's going to get a lot hotter than that - which is why 50% probably is rather generous.

A ground-based plant, of course, can handle much higher internal temperatures (due to more shielding) and thus can get to higher efficiencies. I think regenerators and the like (which allow you to get closer to Carnot efficiencies) also tend to be mass-expensive.