Thinking of the hypothetical scenario where in a short timeframe energy would become near unlimited and almost free:

On the positive side: with no energy limitations, Direct Air Capture technology could be scaled massively. That's one really promising technology that can take carbon off the air and use it for other things (like sustainable air fuels) or removing it altogether.

Also this would accelerate the transition to electric cars and well, electric everything: why pay for fuel for your car, your stove or boiler, when they can be almost free? That has a potential for good effects on the environment too.

On the negative side: this opens the door for more, cheap transport. If people don't have to pay for fuel, they'd be more willing to take the car everywhere. This would mean more roads, more infrastructure, more destruction of ecosystems, less space for pedestrians... A trend that is already too difficult to reverse in a world of expensive fuels.

In terms of economics, I could see this accelerating the gap between countries. Those who could benefit from semi-free energy first would have an immense competitive advantage and also lower their manufacturing costs, leaving worse-off countries in a position where they can't compete because of technology nor because of cheap labour.