If you want to look at things on that timescale, then the tides aren't renewable either. They're gradually slowing our rotation. Once the earth's rotation has

If you want to look at things on that timescale, then the tides aren't renewable either. They're gradually slowing our rotation. Once the earth's rotation has slowed to once per year, we'll no longer be able to extract energy from the tides. Then again, if you want to look at things on that timescale, there's no such thing as renewables.