Currently 88% fossil fuel, 12% renewable:
https://www.worldometers.info/electricity/cook-islands-electricity/ So they have a way to go.
What was in that story was that the power for the EVs in Greece was sourced from renewables - wind and solar.
It's an interesting concept, but I question if it is scalable from a small island. It certainly is a long road to sustainable transport, but we've got to start somewhere.