Harnessing energy from turbulent oceans seems like an excellent source of green energy. The perpetual motion of ocean waves won't result in pollution, carbon emissions or radioactive waste.

But instead of widespread support, marine energy is a controversial subject amongst environmental groups. Among other things, marine energy could lead to eyesores on the beach and could impact fish populations.

A recent article in the New York Times looked at the potential for wave and tidal energies, and the variety of options and approaches that are being tested today. Prototype machines can be found in oceans off the shores of several places, such as New Jersey, Scotland, Portugal, Hawaii and Australia.

There's even a controversial tidal turbine project set to start in New York's East River this fall. As a test project, Verdant Power will provide energy to a grocery store on Roosevelt Island. But it's taken more than three years to get regulatory approval. Rather than finding environmental support, Verdant Power had to contend with concerned fish biologists.

The options and approaches differ significantly. For instance, there's a snake-like contraption called a Pelamis which at nearly 300 feet long is roughly the size of a passenger train. Power can be harnessed through "wave farms," or fields of tidal turbines that resemble giant windmills. Because they need to sit just off-shore, they are likely to face the same aesthetic battles that challenged building wind farms.

There's a huge wind farm a few hundred miles from where I live and whenever I drive by, I'm always impressed by how compelling dozens of massive wind turbines look within the desert landscape.

I'm not sure how a field of tidal turbines might look set against a coastline, but if they're anything like wind farms, I think the idea is, um, swell.