Making Waves: Tapping The Ocean’s Energy

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By Beth Buczynski

Critics of alternative energy like to caution, “The wind doesn’t always blow, and the sun doesn’t always shine,” as a way of demonstrating that wind turbines and solar panels aren’t reliable enough to power the grid. While technological advances are being developed to overcome these inconveniences every day, they do have a point: the sun sets and sometimes there is little or no air movement. What about a natural source of energy that’s always available? Some are looking to the constant motion of the ocean as a solution for society’s energy needs.

Why Waves?

The World Energy Council has estimated that approximately two terawatts (two million megawatts) — about double the current world electricity production — could be produced from the oceans via wave power. Although oceans cover almost 71 percent of the Earth’s surface, research has shown that the western coasts of the United States, Europe, Japan and New Zealand are particularly suitable for wave energy extraction (Chauhan, 2007).

The ocean’s tides are the product of the gravitational pull of the sun and the moon, as well as the Earth’s natural rotation. This movement causes the ocean waters to be raised and lowered regularly throughout the day. The tides have cycles of twelve and one half hours, twice per day, and are easily predictable.

Although finding energy sources without the economic and environmental consequences of fossil fuels might feel like a relatively new concept, people have been trying to harness wave power for many years. As early as the sixth century, tidal mills were used in Ireland, England and France to capture the force of the tides to grind grain and corn. The eighteenth century brought competition from windmills and waterwheels, and tidal mills pretty much became extinct with the invention of cheap steam engines.

The operation of the original tidal mills was very simple: a dam with a sluice would be created across a suitable tidal inlet, or a section of river estuary would be formed into a reservoir. As the tide came in, the water would enter the mill pond through a one way gate which would close automatically when the tide begins to fall. When the tide became low enough, the stored water could be released to turn a water wheel.

While tidal mills were efficient and effective, they are far too simple of a concept to meet modern energy needs. Today’s society runs on electricity, and it wasn’t until 1967 that France became the first country to put tidal wave power to work on a large scale to produce electrical energy.

The Future

Many nations were motivated to take a second look at wave power during the oil crisis of the 1970s, and as the price (and environmental consequences) of oil continues to climb today, energy companies are again trying to develop technology that could harness the ocean’s power.

Although it’s more reliable than wind power, there are still days when the sea is calm. Finding a way to store wave energy for use during calm times is one major obstacle to implementing tidal power in modern nations. Combating the corrosive power of salt water and being able to create equipment that can withstand the brute force of huge storm waves are other limitations that engineers are still struggling with.

Recently, Britain decided to abandon plans for a tidal wave energy project in the Severn estuary following the results of a two-year feasibility study. According to a statement by Chris Huhne, the UK's Secretary of State for Energy and Climate Change, the government did not have enough evidence to substantiate public funding of a tidal scheme at this time.

Most recently, the state of Oregon approved what will be America’s first utility-scale wave power project. The 1.5 megawatt wave energy park will generate enough energy to power 375 or more homes. The park will likely be located 2.5 miles off the Oregon coast near Reedsport, and use ten electricity-generating buoys (Care2).

Beth Buczynski is a freelance writer, avid recycler and amateur gardener with a secret dream of living off the grid. <>.