Ocean Thermal Energy Conversion ( OTEC ): The Future of Baseload, Dispatchable Renewable Energy
Ocean Thermal Energy Conversion (OTEC) is a process that can produce electricity by using the temperature difference between deep cold ocean water and warm tropical surface waters. OTEC plants pump large quantities of deep cold seawater and surface seawater to run a power cycle and produce electricity. OTEC is firm power (24/7), a clean energy source, environmentally sustainable and capable of providing massive levels of energy.
See http://www.makai.com/ocean-thermal-energy-conversion/ for more