But i think steam engines wouldn't have standed in modern times also because of the time needed by the engine to run as compared to diesel or petrol.
Yes, that is mostly true, but steam-turbine engines are still in use in nuclear submarines and aircraft carriers.
Yea they still run and i really wouldn't mind their use. They dont waste your natural resources and they can be affordable. But only thing is are we people of this generation really ready for it. But i really dont have react idea right now about the values generated by steam engine as compared to other two. What efficiency they have have? I think there efficiency might be a problem Sir?