Question

cost effectiveness of water energy over thermal energy

Answer 1

OTEC (ocean thermal energy conversion) was first proposed in 1881. This concept has not been properly developed. The oceans on earth already stored more than two years of solar energy transmitted to earth in the thermal form in the top 1000 meter depth. Tropical ocean with surface to 1000 meter depth temperature difference of 20 C can power Rankine cycle heat engines using ammonia as working fluid to provide more than 50 tera-watt of electricity at 2 cents per kilowatt hour.