Apparently Johnny Depp bought an island for around $3,000,000 a while back. And, since there aren't exactly power lines running to the tiny island, he had to figure out how to power his (ridiculously posh) home. For the green-minded Depp, diesel generators just weren't an option.
So he turned to Mike Strizki to help him build a system that would produce enough power to quench his celebrity-born thirst for decadence while not throwing off massive amounts of greenhouse gas. The result is a solar system that stores excess energy as hydrogen for use at night, or during cloudy times of day (not too common in the Bahamas, but still.)
The system, to me, seems vastly inefficient. Hydrogen gas is terrible at storing energy in a small space unless it can be compressed a great deal. But Strizki's system uses propane tanks to keep costs low. The result is that 10 thousand-gallon propane tanks are needed to store enough hydrogen to get the island through the night. You can see a video of his less exotic system (in New Jersey) here.
Power storage for renewable systems is a huge deal. But this strikes me as a rather inelegant solution. But a high pressure tank would be costly, and of course require an energy-hungry compressor. So maybe Depp's system is the best we're going to get.
In any case, it's hard to call any of this green when the excesses of owning your own island are so obvious. But I suppose it's better than complete disregard for the environment..