It has to do with the density at it's operating state, which is a lot closer to water than steam. It's the same reason a 1m radius water turbine can produce abo

It has to do with the density at it's operating state, which is a lot closer to water than steam. It's the same reason a 1m radius water turbine can produce about 1MW of energy, but an air turbine of equivalent power might have a radius of 50m.