Ocean Power

Most any surfer can tell you that the ocean’s tidal currents can pack a serious punch. It is this basic principle that raises the question of whether or not the oceans power can be harnessed and converted into energy, similar to the way that rivers drive hydropower dams or wind drives wind turbines.

According to John Lienhard, a University of Houston mechanical engineering professor, the concept is a no-brainer: “Every day the moon’s gravitational pull lifts countless tons of water up into, say, the East River or the Bay of Fundy. When that water flows back out to sea, its energy dissipates and, if we don’t use it, it’s simply spent.” Energy Quest, a highly informative educational website of the California Energy Commission, suggests that the sea can be used for energy using three basic methods: wave power, tidal power, and ocean temperature variations via the “ocean thermal energy conversion” process.

Wave Power
In this process, the back-and-forth or up-and-down motions of wave patterns can be captured, for instance, and used to force air in and out of a chamber to power a piston or spin a turbine that may power a generator. There are even some wave power operations in place today that power lighthouses.

Tidal Power
Using tidal energy, on the other hand, requires trapping the water at high tide and then harnessing its energy as it flows out and drops in its reversion to low tide. This is not unlike the way water powers hydroelectric dams. Some large installations in Canada and France already generate sufficient electricity to power thousands of homes.

Ocean Thermal Energy Conversion (OTEC)
The OTEC system uses temperature differences between surface waters and deep waters to extract energy from the flowing of heat between the two.

Supporters of ocean power say that it is superior to wind power because tides are more consistent and predictable and that the natural density of water makes for fewer turbines needed than it would take to produce the same amount of power as wind. However, considering the general difficulty as well as significant cost of constructing tidal arrays at sea and funneling the energy back to land, ocean power is not yet a feasible energy alternative in most situations. It is expected that as technology advances and demand for renewable energy increases, the cost of producing ocean power will decrease substantially. Some experts predict that in the foreseeable future, ocean power could account for as much as 2% of the total power grid.

The pioneers of tidal energy are hard at work all over the world, as well as here in the United States, trying to develop the technology as efficiently as possible. In fact, The New Hampshire Tidal Energy Company is currently developing a tidal power in the Piscataqua River, located between Maine and New Hampshire. There is also a similar company called Verdant Power providing energy to New York through tidal river turbines, and they are also in the process of installing tidal power systems in the East River in New York City.