Yes, we need sustainable but not necessarily renewable. I was reading about harnessing the power of waves, which is also unlimited, but for what we want it definitely has its limitations. They've been talking about cold fusion using water since the 80s, but it still doesn't seem to be any closer to fruition than it was back then. When I mentioned it in a discussion, the possibilities of ITER and TOKAMAK were brought up, which may be something we could do on a faster time scale?Yes, sustainable is a far better word and should replace renewable.
Nuclear fuel needs to be mined, whereas wind and sun are directly available for as long the planet can sustain life, but mining can be fine as long as new areas aren't taken up faster than nature can reclaim. Maybe we can say that fusion power is renewable if all the fuel can be produced from water, whose supply is practically unlimited. Like power from tidal forces, not strictly unlimited, but certainly for our purposes. However, a fusion plant could require large amounts of rare elements to be built. Power production would be sustainable, but one could argue that expansion is not.
https://www.iter.org/proj/inafewlines
How close are ITER and TOKAMAK to being realized?