Seems like a good time to ask this question that has been bugging me forever, since all the HN jet nerds will be drawn to this thread: Why hasn't anyone made a hybrid car that uses a gasoline-powered turbine generator to charge its batteries instead of a piston engine? I'd imagine that hooking up such an engine directly to the drivetrain like in a Prius would be difficult, but surely a small turbine with one hell of…
I've been wondering about this very same question a lot myself and accidentally stumbled across the answer just a few days ago: Efficiency of turbines smaller than grid scale is simply not anywhere close to what piston engines can do at e.g. car size. Even at naval scale, turbines only win in use cases where power density is more important than fuel efficiency. Helicopters are deep in the (specific) camp of power den…
The issue isn't that they're not efficient. It's that they are only efficient at high power level, and the minimum power level they're efficient at (and even their minimum power level, period) - is quite high. To compare: Britain's current aircraft carrier has four diesels that total 40MW...combined those diesels equal one of its two 40MW turbines.
This minimum power level is why jet airplanes have an APU, and often taxi with just one engine running, with the second started up with enough time to get up to operating temperature for takeoff.
Example: https://en.wikipedia.org/wiki/Rolls-Royce_MT30
~40MW, minimum efficient power level 25MW.
25MW, even if it's very efficient in terms of turning kerosene into shaft power, means the ship is moving really fast, and thus there's enormous fuel consumption and drag.