A Ted talk:
I visited Costa Rica several times and I believe they are in that range also. They have a combination of hydro, wind and geothermal (volcano) technologies that they have invested in.
The federal Energy Information Administration estimates that 77% of Hawaii’s power comes from burning fossil fuels, mostly oil and some coal.
We are looking at 22 years or less to fix that.
To generate 100 percent of its electricity from renewable resources by 2045, Hawaii is aggressively pursuing renewable energy projects in bioenergy, geothermal, hydroelectric, and hydrokinetic power, as well as continuing its extensive investments in solar and wind power.
Unlike the other 49 states, Hawaii can’t suppliment power by purchasing it from neighboring producers (the grid). In fact, we are not and pretty much cannot produce power on on island and send it to another. The Big Island could be a large producer of energy but sending it to Maui, just 30 miles away has issues. The channel between the islands is 6,000 feet in spots and is called the most dangerous channel crossing in the world. Winds can top 50mph and swells exceed forty feet, commercial tug-trips get cancelled!”.
Our geothermal production was halted when a recent lava flow almost encroached the site.
The north and south side of our island has windmills. There is an investigation into wave power.
Since the Hawaiian Islands are still “under construction” I would guess geothermal sources are as unpredictable as they are plentiful.
I guess you can blame the tectonic plates for that problem …