[Thalass]

One advantage of a steam engine genset would be that, being an external combustion engine, it could run on just about anything, and the flame could be tuned to burn completely - reducing emissions - as long as you could feed the fuel into the fire in a controlled way. Unfortunately piston steam engines aren't much more than 10% efficient, and steam turbines aren't much better.

Stirling engines are also external combustion, but are (theoretically) very efficient. But they also have very low torque, so would need to be run at very high rpm and geared down to useful levels.