1 hp = 746 watts. 150 kw = 201 hp You would have to be able to get at least 201 hp @ 1800 rpm. Typ gen sets use a helluva lot more hp than the above calcs depict... typ double.
If you are talking about electric motors, a 1 hp electric motor will suck a lot more than 746 watts. That 746 w per hp is only if the 1 hp electric motor was 100%..and they are not, more like 65% eff.
746 / .65 = 1148 watts.
I have yet to see any generator that didn't spin at 1800 rpm. None had any tranny or gear box used. All were direct drive..with just a pair of U joints.
I have some old GE , V-16 Turbodiesel locomotive generators that spin at only 900 RPM. 2 MW / 2.5 MVA.
They are some of my largest. We do paralleling for increasing capacity and redundancy.