Here’s an article about a “Perfect Storm for Renewables,” which describes how Kauai, one of the less-populated Hawaiian Islands, is poised to hit 40% renewable energy on their electricity grid. This is largely driven by homeowners who have installed solar PV, which already provides an enormous chunk of the island’s peak energy.
In truth, it wouldn’t be impossible to achieve 100%, and then go on to replace gasoline powered cars with electric vehicles. Of course, this would require energy storage, by far the most popular form of which is pumped hydro – the three components of which are off-peak energy, water, and elevation. Good news for Kauai, which boasts places of 5000+ elevation and 400 inches of annual rain.
In fact, harnessing the hydro resources alone (forgot about pumping it) from the highest and wettest part of the island would generate about 150 MW, according to my calculations based on this chart, where I estimated that 15% of the island’s 562 square miles receives an average of 200 inches of rain, which then falls an average of 2000 feet. That’s more than enough for the entire island, which is currently at 125 MW, even without the PV.