Compressed air technology is still widely used and developed further by "high-tech" engineers; thus the lecturer seems too pessimistic to me.

It is correct though that the public discussion on energy problems is highly marked by vested interests. It is a solid fact that ecologically neutral energy can be produced very cheaply with existing technology, in amounts exceeding the needs of all mankind by far. Those who deny that are either deceived or liars. (In comparison, the prediction of global warming is only based on very plausible hypotheses.)

In particular, the overall costs of nuclear plants are being understated intentionally, because they seem to be payable only in the "distant" future, or in sufficiently improbable disaster cases. Today's investors hope that someone else will pay in the end, and politicians have even less incentive to plan ahead, unless their voters demand it forcefully.