Fuel Cell 2000 - Fuel Cell Information
OTEC (Ocean Thermal Energy Conversion) uses the temperature difference between
   the warm surface water and the cold deep water of the ocean to produce energy.
ICLEI's Energy Facts has a good introduction to OTEC
Ocean Planet: Popular Science has a good paper on the pros and cons of OTEC
Kailua-Kona was the first OTEC plant
Solar The Solar Cooking Archive