First coal fired power stations do NOT send 60 to 70% of the energy up the chimney. The boilers of modern power station are 96% efficient and the exhaust heat is captured by the economisers and reheaters that heat the air and water before entering the boilers.
I'm not sure where he got this figure from but the most efficient single cycle coal fired power station in the world has 45% thermal efficiency. A power station like Hazelwood is probably near 30% efficient and the newer ones around 35%-40%. To get higher than 40% you need combined cylcle power stations which use gas turbines and utilise the byproduct heat to further drive steam turbines.