Super. Hopefully other states and countries will soon follow Hawaii's lead. 100% renewable electricity is simple to implement in any country using solar and wind power. Intermittencies are dealt with in four principal ways:

1) Using battery backup like Tesla's powerpacks.

2) Long-distance transmission lines connecting the grid over large geographic areas (ideally the entire planet should be connected into a super grid). Solar and wind produces a constant flow of energy on average on the planet.

3) Overcapacity. Seasonal intermittency can also be dealt with by building enough solar and wind power to supply the grid even in seasonally low production times (such as low winter production for solar energy and low summer production for wind power).

4) Implementing a smart grid enabling hourly changes of the electricity prices for every meter on the grid in order to fit supply and demand at any time of the day or the year.

Let's consider the probable cost of the 4 main ways of dealing with intermittency in a society that is 100% powered by solar and wind power (Indeed it is indirectly nuclear energy as it all comes from the massive fusion reactor at the center of our solar system. Solar and wind is a genius way to implement nuclear power in a safe manner without any radioactive waste on our planet or powerplants that risk exploding and make enormous areas inhabitable for hundreds of years).

Add 1) Tesla's power packs costs 250 USD /kwh. Musk said they can do 5000 cycles. Add 50 USD /kwh to combine them in large systems at each substation on the grid. That is 0.06 USD /kwh (=(250+50)/5000)). You probably only need to store 30% of your consumed kwh in batteries. The rest is used directly. So the price for battery backup is 0.018 USD per kwh consumed (=0.06*0.3).

Add 2) Building lots of long-distance transmission lines globally is expensive but probably can be paid for by adding 2 cents per kwh consumed.

Add 4) Building and maintaining a smart grid with price adjusting meters is not costly at all. The meter may cost 200 USD and the network data traffic for 20 years use may add another 100 USD. Over 20 years the meter in a household may measure 200.000 kwh so only about 0.0015 USD /kwh for the smart grid feature (=(200+100)/200000).

Combine the cost of 1, 2 and 4 and we get 0.0395 USD /kwh. This is really not that much for clean air and saving the planet from global warming disasters (like mass extinction of species).

Still these solutions may not be enough to deal effectively with the intermittencies especially the seasonally ones. So solution 3) about overcapacity should also be added. That is the solution you start to use when you want to go from say 70% renewable to 100%. The world is currently at 6% electric generation from solar and wind power so we can safely assume we will not need to implement solution 3) until at the earliest in 2040. Today wind power is 0.06 USD per kwh and in 2040 it is at most 0.03 USD per kwh. Today utility scale solar power is about 10 cents per kwh but it will also be about 0.03 cents in 2040. So 0.03 USD /kwh for both solar and wind in 2040. How much extra capacity you need to be certain to have enough in low production seasons will depend on the climate you live in. Near equator you could probably do with 110% of the needed capacity but high up north and south of equator it will more lileky be 150%. So assuming 150% it would make electricity cost not 0.03 USD/kwh in 2040 but rather 0.045 USD. Now add the 0.04 USD /kwh from 1, 2 and 4 and you get an industial price of electricity of 0.085 USD /cents. Add distiution cost and households will end up paying about 0.014 USD /kwh in the US. Not a big deal really for clean air and a healthy planet. And we assumed Tesla's batteries will not drop in price.

An impressive act of leadership by the Hawaiian government. Thirty years is plenty of time to get to 100% renewable grid mix. Hawaii currently burns oil for electricity, which is why its electricity prices are the highest in the nation. A move to renewables will pay dividends to future generations. The main significance is to remove the impediments to solar, something Hawaii's utilities have long been criticized for.

The "impediments to solar" are "the fixed costs and essential operating characteristics of the generators which keep the grid stable instead of blacking out".

The Hawaiian utilities have been handed a problem not of their creation, that nobody has solved satisfactorily (which is why solar generation never made it even in e.g. sunny Egypt despite CS demonstrations a century ago), and told to fix it.  The only fair way to handle this is to tell the owners of solar power to fix the problems THEY created:

1. Buffer their power output to provide dispatchable power.
2. Provide or pay for rotating machinery, like synchronous condensers, so that the grid has the sheer mechanical inertia which keeps it stable.
3. Supply reactive power.

Hawaii Islands may be ideal for test sites for 100% RE.

Islands like Maui with large sunny mountain tops (very sunny and almost above louds are ideal to produce solar power. Pumped Hydro could be one of the storage solution.

Of course many dry desert areas may offer even more solar energy but access to water + sufficient elevations for pumped hydro would be limited?

Each Island could have its own energy system. Most of those Islands have large high mountains tops mostly well above cloud covers. Oriented solar systems could produce 8+ hours/day.

Sea water could be desalted, pumped and stored xxx-ft high during surplus periods then used for agriculture and industries + to produce essential e-energy overnight. Most desalted water would be used at least twice, ie. to produce e-energy and for agriculture/industrial uses.

Some system could use salted sea water and return to sea after used to generate e-energy.

It could be a win-win solution.