My boss plunked down an article on tidal energy from an in-flight magazine that explored how several companies are harnessing the ocean tides and swift river currents. Far less developed and popular than its cousin wind energy, it would seem there’s something to this. Ocean Renewable Energy has developed an OCGen meodule, which looks like a double reel lawnmower with a generator in the middle. Under development with plans for a 2010 commercial launch, it promises to “generate up to 250 kilowatts in a 6 knot current (varies with current speed).” That last caveat is big because such technologies such as wind and tidal will need huge batteries to back them up during slack periods. That said, ocean tides and river current are more predictable than wind. The Fall River-based company is planning projects in Maine and Alaska. You can watch a video of Verdant Power plopping its more conventional turbines into the New York’s East River. Others mentioned in the piece include Irish company OpenHydro with a jet engine like design and New Jersey-based Ocean Power Technologies. They all have distinctly different designs and are worth a look.