Well, Michaelis's idea is to use the warmth of the ocean, not the direct sunlight, or as well as direct sunlight.  I would more imagine as you suggest Andrew that the dirt poor countries of western Saharan Africa in particular - but anywhere with a decent amount of sun - Australia since it has such a crap record on CO2 and energy production - using their sun and sea water to produce hydrogen, at the same time perhaps as "greening the desert" - at least the populated bits of it.  Though I also read an idea yesterday I think that someone said you could could add energy (ie from the sun) to CO2 and water to produce not just hydrogen but proper hydrocarbons - methane mostly but most others could be synthesized from that.  I like my hydrogen idea better though as then it doesn't also pollute when burned as a fuel like methane would.

Also another idea I noticed the other week was that those countries with swathes of tropical rain forest could be paid for not cutting it down.  They are protecting a precious natural resource we all need - why not pay them to keep it at least as much as it pays them to cut it down if it's so important to planetary function.