One technology we don't hear much about is wave power (at least not here in the US). EveWasRight writes about a recent study that points out the potential of harnessing the energy of the waves.
Wave energy systems place objects on the water’s surface that generate energy by rising and falling with the waves. The wave energy in turn moves a buoy or cylinder up and down, which turns a generator that sends the electricity through an undersea cable to a power station on the shore.
...The potential energy to be captured from ocean waves could surpass the other forms of renewable energy such as solar, wind, or hydropower, according to a recent study by the Electric Power Research Institute (EPRI), a research group funded by hundreds of utilities.
According to a report released in January, 2005, the total wave power along the coastlines of the U.S. is approximately 2,100 terrawatt hours per year, nearly as much as all of the electricity produced by coal and roughly 10 times the total energy produced by all of the country’s hydroelectric plants.
The study's author says that wave power compares favorably with other energy sources.
Wave energy systems can capture the same amount of energy using smaller and less expensive equipment than wind or solar systems, according to Roger Bedard of EPRI, who authored the study.
Wave energy “is among the most environmentally benign technologies,” and is less visible than off shore wind farms, according to Bedard. He says wave energy conversion devices have a smaller footprint than offshore wind farms and interfere less with marine life movements.