Many think finding a way to generate energy sustainably will be the biggest challenge for our generation. We know it’s a possibility to use sustainable energy to meet all our energy needs, but many of the long-term strategies seem stranger than fiction to us today.
One of those fictions will soon grow closer to a reality: getting energy straight from the force of the ocean’s waves. A company in New Jersey is putting the final touches on a buoy that will have the capacity to do just that, and should be ready to be launched off the shores of Portland, Oregon as early as October. The company was recently granted a federal permit to launch 10 such buoys, which will be the first wave-power devices ever to be hooked into the U.S. power grid.
These 10 generators could power as many as 1,000 homes. More importantly, they could open up an entirely new sustainability energy market. Another new buoy set to be launched off the coast of Oregon in the near future is a prototype built in collaboration between an Oregon based energy company and the New Zealand Government. Both of these ventures may be catalysts that ignite new interest and bring new funding to wave-power technologies in the Northwest United States.
Used effectively, tidal wave energy could compete with solar and wind energy in terms of costs. Although not all coastal sites could efficiently harness the energy of waves, many areas have been identified as well-suited for this form of energy generation, such as America’s Pacific Northwest, Western Scotland, Southern Africa, and Australia—all places that have constant winds that generate a constant supply of waves. While wave energy is usually glazed over in conversations of renewable energy, this kind of wave generation has huge potential and is getting closer to bearing fruit.
However, high initial costs and a history of failed projects have hindered the development of tidal energy buoys worldwide. As is the case with wind energy, the initial costs of developing and constructing energy generators are high. This first buoy built by the New Jersey non-profit Ocean Power Technologies was slated to cost $4 million at the project’s onset. The other nine buoys were presumed to cost a total of $60 million in total.
Supporters of the project hope that the new technology does not suffer similar fates to its predecessors. A buoy launched by a Canadian team of researchers in 2007 sank to a watery grave at the bottom of the ocean just months after its highly anticipated launch. Although it succeeded in gathering the data it had been designed to obtain, its sinking dampened the enthusiasm surrounding the project. Portugal was the first country in the world to develop a coastal wave farm, launched in 2008, which was capable of powering more than 1,500 homes. Compilations arose, however, and the buoys were returned to shore just two months after the project was begun. Management issues within the company financing the project lead to the buoys never being restored to service.
The technology available for the capture of wave energy is evolving quickly, and there is still a wide range of techniques being developed that vary significantly from one another. The current favored technique, called the Oscillating Water Column system (OWC), is advantageous because it is relatively simple in design and more economically viable than other systems. In OWC buoys, a water tight, rectangular chamber, open to the sea at the bottom, becomes filled with high velocity, highly pressurized air. This is due to the compressing and decompressing of the air inside the chamber as waves pass beneath it. At the top of the chamber exists a conical air duct, which allows air to pass into and out of the chamber as pressure inside is changing. Within the duct, there is a special turbine known as a Wells turbine, coupled with an alternator/generator that produces the electricity. The Wells turbine is unique in that it turns in the same direction regardless of the direction of airflow, so it moves continuously as waves rise and fall beneath it.
In order to be fully efficient, these buoys must adjust the amount they rise up as a wave passes beneath them. That is why the buoy under development by Ocean Powers Technology has been equipped with an array of devices to help it adjust to each incoming wave. With the help of “wave riders,” an umbrella term for a number of small devices that float farther out in the ocean and provide the buoy with information about incoming waves, electronics in the buoy can adjust how it will respond to each wave that passes under it. This system is meant to optimize power generation, and prevent inconsistencies inconsistencies in power generation due to inconsistencies in wave size.
However, this is not the only system that has been put into use. The Portuguese wind farm of a few years ago used a different kind of wave capturing system — the attenuator model. These do not look like buoys, but are long and skinny tubes that float on the surface of the water connected by hinges. These devices are anchored to the seabed. As waves hit them, the cylindrical parts drive hydraulic rams that use differences in water pressure to create energy and to power a generator.
A potentially highly efficient model of wave power generator, at the research stages, is a design known as Salter’s duck. Salter’s duck is able to convert wave energy into usable electricity with an astounding 81% efficiency in lab conditions, although predictions of its efficiency under realistic conditions have been as low as 50%, which is still very high by today’s standards. Salter’s duck is comprised of a string of floating “ducks” mounted on a central spine that links them all to one another. The ducks are oriented in a way that wave impacts cause them to flip over in the water. When this happens, four gyroscopes inside each duck begin to move back and forth, creating energy that can be transferred to a turbine or electricity generator.
Wave energy is a hot topic in sustainable energy research, and it is the key in tapping the enormous amounts of energy in the ocean’s waves and currents. Theoretically, 0.2 percent of the energy in ocean waves would itself be enough energy to power the entire planet. And, unlike solar and wind energy that are not always readily available depending on weather conditions, ocean waves in many parts of the world provide remarkably consistent amounts of energy in all weather and seasons. Moreover, wave power does not produce greenhouse gases like fossil fuel burning does, and is not known to disrupt local ecosystems like other forms of hydroelectric power do (although this is a topic of ongoing research). If we are capable of creating systems of energy capture as efficiently as Salter’s duck, who knows how much of the ocean’s vast energy supply we will be able to one day capture as technologies improve and projects become more economically viable. Perhaps the future of renewable energy will not be marked by fields of solar panels or farms of wind turbines, but by networks of high-efficiency wave farms extending off of our continents’ coasts.
