Yes.

We can easily generate more than enough renewable energy, just not when and where we need it. Being able to transmit energy over vast distances would greatly improve the economics of our existing renewable energy generation solutions.

>In the most idealistic scenario, you could imagine a belt of solar power plants around the globe connected by superconducting power lines

There's no technical impairment for doing this with current tech, and it's not clear the new tech (if it works) is cheaper.

Power lines are already very efficient, especially the long-distance ones. We would save a bit on converting from HVDC to AC but that's also very efficient.

The numbers I found on a quick search are 3% loss per 1000 km for HVDC lines. That's a pretty huge loss for the 20k+ km lines you'd need to transmit power from daytime to nighttime areas on the globe.

I thought these were mostly fixed conversion losses, but checking this again you're right, it's 3% per 1000km (not including the conversion loss at the stations).

There absolutely is. Once you think about this on a global scale HVDC doesn't quite cut it. You can extend the day/night cycle by a few hours each way, which is already very impressive but it isn't enough to cover 24 hours and it definitely isn't going to help you in winter when you want to transport energy from the sunny hemisphere to the darker one.