Alexander's Wonderful Machine
The amount of power that could be produced from ocean currents almost defies comprehension. The currents flowing through San Francisco's Golden Gate alone, for instance, could produce an estimated 2 gigawatts per day -- more than twice what the city needs at times of peak demand. The global potential is some 3,000 gigawatts, according to the United Kingdom's Department of Trade and Industry. The agency estimates that 3 percent of that total, or 90 gigawatts, is economically recoverable using current technologies.
The article is a bit too hopeful, but it is already being implemented in Korea.
Last fall, South Korea commenced the second phase of the project, when it installed a 15-foot turbine in the strait. During this phase, it hopes to produce up to 1,000 kilowatts of power that will be sent to Jindo Island, with a population of some 40,000. If that goes well, the government plans to install thousands of Gorlov's underwater turbines, hoping they can harness from Uldolmok and the surrounding oceanic streams up to 3,600 megawatts of power -- about equal to the output of four nuclear power plants.
I believe the remaining fossil fuels should be used to subsidize the energy required to setup and maintain renewables such as this. This won't solve transportation systems, but it definitely is nice to have heat, lighting, and computers.