Yeah, drop-in or add-on
I'd expect to see these in co-generation plants first. Besides, anyone who invented the Super Soaker probably knows how to get his tech out into the real world.
The only thing that concerns me is: high heat + high pressure hydrogen gas = Hindenburg? As many folks (I can't tell if they're anti-green or just anti-hydrogen) have pointed out hydrogen is just a medium of energy storage. Where do you store the hydrogen when the sun isn't shining? If you keep it in the heat engine, it will slowly leak out.
OK, I'm sure better minds than mine have tackled the hydrogen gas storage/inflammability problem. Maybe combine it with carbon to form methane...the lesser of two evils? Just throwing out random ideas here.
Also, Saudi Arabia may have loads of desert sand to play with, but so do multiple other countries. Nobody has a monopoly on sunlight (unless you're talking about Mr. Burns in the SunBlocker episode of the Simpsons). Also, you aren't going to run out of sunlight in the next 100,000 (give or take 5 million) years or so. I don't think even the non-peak-oil people believe that oil will last forever.
Darn...I was hoping that anti-matter would save/kill us all. I'd better get to the asteroids first.