Jet turbines have a much narrower range of efficient operational speeds than combustion engines. The Navy figured this out circa 1900. For emergency power whe

Jet turbines have a much narrower range of efficient operational speeds than combustion engines. The Navy figured this out circa 1900. For emergency power where you have basically unlimited potential load and can add more stuff to ensure you won't need to throttle below your sweet spot and don't care about wasting fuel to keep the lights on anyway that's fine but freight locomotives and shipping stick to their legacy piston rings because the overall system efficiency winds up being greater in their use cases.