The Ocean's Power

July 19, 2006 - Ken Silverstein, Editor-in-Chief - EnergyBiz Insider

When Maine decided to enact an energy bill that would require 10 percent of its generation sources to come from renewable energy by 2017, it knew the task would be challenging. To get there, it will try and take advantage of one form of green energy that gets little attention: ocean energy.

In fact, the Electric Power Research Institute, or EPRI, has said that ocean power in Maine has the potential to produce electricity that does not emit harmful pollutants at a cost that is on par with wind and solar energy. And ocean waves may be more reliable than other green energy forms, largely because the tides are constant.

The potential is obvious: As the world's largest solar collectors, the oceans generate thermal energy. Now the job before scientists and engineers is to figure out how to capture this energy and produce electricity. Sea water is 832 times as dense as air, providing a six mile per hour ocean current with more kinetic energy than a 217 mile per hour wind, say experts. To bring the idea into the mainstream, however, scientists and engineers must still show that their work can be done on a large-scale basis.

"Ocean wave energy enables more straightforward and reliable integration into the electric utility grid to provide reliable power," says Annette von Jouanne, engineering professor at Oregon State University, in a release that notes the school is testing the viability of ocean power. "Wave energy also offers much higher energy densities, enabling devices to extract more power from a smaller volume at lower costs."

The World Energy Council says that ocean power could provide as much as 10 percent of the world's electrical demand. The catch: The technologies to allow that are not yet ready for prime time. That said, the United States provides some possibilities.

The shores off the California Coast and Washington State could be sites for ocean power plants. Seattle-based Aqua Energy wants to build a one megawatt facility near Washington State that forces water through a buoy that spins a turbine generator to create power. That so-called tidal fence uses turnstiles that spin with tidal currents. Florida and other areas of the Gulf of Mexico are also suitable for such development.

In the case of Maine, it has filed two preliminary permits with the Federal Energy Regulatory Commission. Experts say that ocean power could be generated for no more than 6.5 cents a kilowatt hour. While more expensive than coal resources, the chief advantage would be the fact that such plants would emit no greenhouse gas emissions.

"Harnessing the energy from Maine's big tides in an environmentally friendly manner will reduce our dependence on imported fossil fuels and will create jobs in the state," says Beth Nagusky, director of Maine's Office of Energy Independence, in a previously published news report.

Pilot Projects

Altogether, the U.S. Department of Energy says that there are only a few hundred land-based sites in the tropics where deep-ocean water is close enough to shore to make ocean energy feasible. At the same time, it says ocean energy does present environmental challenges. Tidal power plants can impede sea life migration and can effect local ecosystems. In Oregon, for example, they are studying the potential affect on sea birds and marine life from electromagnetic fields and undersea cables.

Newer technologies, however, are less problematic and don't block migratory paths. The optimal solution is careful site selection. That involves appropriate spacing of the plants and choosing sites that preserve scenic shorelines.

To make ocean energy economics work, it will need to be done on a large-scale basis. France's La Rance station is the only industrial-sized tidal power station -- gates and turbines are installed along dams -- in the world. The plant, which went on line in 1966, produces 240 MW. The Annapolis Royal Station in Nova Scotia, Canada, meanwhile, generates about 20 MW of power using tidal power.

The United Kingdom could also be a potential spot for ocean power. A proposed off-shore project near Lynmouth would be capable of producing 300 kW of electricity and will become a testing ground for other tidal turbines.

Indeed, the U.K. has announced it could host its first large-scale ocean power project -- one that could be operational within a few years. That announcement coincides with others. South Korea, for example, is working on a large tidal and wave power plant that would be able to generate 254 megawatts.

"The potential of (ocean power) is great," says Joseph Huang, a senior scientist for the National Oceanic Atmospheric Administration, in a news report filed by freelance writer Carl Hoffman. "The oceans are the biggest solar collector on Earth, and there's enough energy in them to supply a thousand times the world's needs. If you want to depend on nature, the oceans are the only energy source big enough to tap."

While the technologies to produce ocean energy exist, they have a long way to go. But, the U.S. Energy Department does have a program to assist developers and it is funding one such ocean energy project 11 miles off the Florida coast that would produce 120 kW. Meantime, Blue Energy of Canada has developed six prototypes that produce up to 100 kilowatts. The tidal fence, which acts like underwater windmills, allows water and marine life to safely flow through.

It's clear that renewable energy will play a greater role in bringing electric power to people all over the world. Wind and solar energy are the most advanced forms of green energy. But, ocean power has the greatest potential. The key now is to get a few such facilities up and running to demonstrate its viability.