Upto 90% (80-85% in practice) efficient turbine technology already exists, but India's power plants are all unupgraded vintage shits that run at 30-35% efficiency like fucking IC engines.
Frankly solar & wind are getting efficient too. We've already got 10GW solar field planned in Andhra. Few square kilometers of barren waste land us all it takes, overall water consumption is lower too.
Coal lobby.... and Javadekar is a sack of shit.