The waves contain an almost infinite potential of energy, but taking advantage of the incessant movement of the sea continues to pose great technological challenges. Annette von Jouanne explains to Angela Posada-Swafford how her revolutionary buoy system will be able to extract electricity from the oceans.
“Even when the sea seems calm, the waves are constantly moving the water up and down, enough to produce energy in a renewable and predictable process.”Annette from Jouanne, Professor of Electrical Engineering at Oregon State University, arrives crystal clear and energetic by phone from the west coast of the United States. “It is feasible to think thatThe electricity generated by the waves will supply, in the not too distant future, at least 10% of the energy needs of states like Oregon or countries like Portugal, thanks to its excellent geographical location “.
Von Jouanne knows exactly what he is talking about. Not only as an engineer and inventor of revolutionary electrical systems, but as a true marine creature: at 40 years old, she has spent more time swimming or surfing than on land. Her closest collaborator is Alexandre Yokochi, a doctor in Chemistry and former Portuguese swimming champion with whom she has been married for 16 years and has had three children. “Every day we swim in our special exercise pool. The surf is always on our mind,” he says with evident pleasure. But the inspiration to find the wayharness the power of the oceans“in a practical, efficient and responsible way” came to her long before, when she was a 26-year-old student surfing in Hawaii. “The sun was beginning to go down on the horizon and there I was, sitting on my board in the water, gently rocking me.
And then something clicked in my head. The waves! “, Says this expert. And adds:” I could ride on them all day and all night, because their energy never runs out. I began to think that there should be a way to channel all that energy in a clean and relatively easy way. And I never stopped thinking about it. “Today, Von Jouanne is the driving force behind the most cutting-edge research in the emerging field ofrenewable marine energy. His university laboratory, theWallace Energy Systems & Renewables Facility, can be considered the most sophisticated of its kind in the United States. “What I did with the members of my team was to design several prototype buoys capable of extracting energy from the waves very efficiently,” he summarizes. For decades, engineers have built scores of complicated machines for the same purpose, but all these inventions are characterized by many moving parts that reduce their productivity. For example, the Portuguese have developed the Pelamis Wave Energy Converter, a linear attenuator or absorber that at first glance resembles a long jointed snake moving parallel to the direction of the waves.
“It’s about ahydraulic system with seven conversion stages between wave and electricity production“Explains the engineer.? All these elements – she continues – reduce energy efficiency. Now, Pelamis is a commercial project, and I understand that they have chosen a technology that is already mature. In our case, as university researchers, what we did was create a simpler system, which we calleddirect drive. With this expression we mean that we obtain a direct coupling of the wave speed and force with the buoy. Our ingenuity is not based on hydraulic mechanics, so we eliminate fluid compression; and it is not pneumatic, with which there is no air compression either. This drastically reduces the number of phases involved in the process.?
Water is 822 times denser than wind, allowing more energy to be extracted from a smaller volume
In the last 11 years, the center of Annette von Jouannehas developed 18 prototype buoys, with the collaboration of the US Navy and the renewable energy company Columbia Power Technologies. Among all these models, they chose the five that they considered most suitable to be built on real scales and tested in the university’s test tank. “Our achievement was designing a system with only two main components,” says Von Jouanne. “The first element is a pole that remains anchored on the seabed. The second consists of a magnet attached to a donut-shaped float that slides freely to the rhythm of the waves. As said magnet moves, its magnetic field it also runs along a copper wire threaded into said post. This displacement induces a current in a cable. It’s that simple. “
Think of a large four meter diameter mushroom on a 35 meter tall stem. Now imagine a flower arrangement that groups several of these mushrooms in a coastal area of five kilometers. This is Von Jouanne’s vision. Thebuoysthey will work, she says, because all waves, regardless of their size, contain energy. “A small one, say 1.5 meters, generates about 10 kilowatts for every meter of width of the crest. In winter, Oregon waves reach 3.5 meters. At this height, they produce 50 kilowatts for every meter of wide, “he explains.
This expert is convinced thatbunches of buoysthey would allow places like the state of Oregon not to have to resort to oil rigs on their shores. Now, how do you compare the energy efficiency of waves with wind generators? “Wind is also a wonderful alternative source. But it happens that the density of water is 822 times greater than that of air, which means that more energy can be extracted from a smaller volume. And that translates into lower costs. “. Other advantages of the waves compared to the blows of Eolo are its greater availability – there is always, to a greater or lesser extent – and that it is predictable at 90%. “The latter is extremely important for companies, because that way they can determine exactly how much electricity a buoy installation is going to contribute.”The best places to take advantage of it are the coasts that face west -such as Oregon and Portugal-, due to the prevalence of global winds, which blow from west to east..
Another important challenge for Annette von Jouanne lies in preventing the sea, with its enormous corrosive and invasive power, from destroying the buoys. “We are exploring next-generation composite materials,” says the expert. “That is the area my husband is investigating: how to manage to inhibit the growth of algae or other forms of life that interfere with the movement of the float. Alexandre has discovered that sometimes it depends not so much on the material used, but on its shape and texture. I found that aspect very interesting. “
Von Jouanne is also calibrating thepossible environmental effects of your facilities. For example, he hired a marine biologist to study how tokeep the whales away, since annually 20,000 cetaceans migrate off the coast of Oregon. “All animals are attracted to the electromagnetism that buoys produce. That is why we are testing annoying – but not dangerous – sounds that drive mammals away.”
Although energy from the ocean is a rapidly taking off field, there are still many unresolved issues. That is why the Von Jouanne laboratory is inviting power companies, universities and research institutes from around the world to test their own renewable marine energy systems in its specialized pool.
“My philosophy is summarized in thatextracting wave energy is a very productive endeavor that deserves to be explored thoroughly and internationally. We have to make the tidal wave part of our arsenal of renewable and clean energy. “
Angela Posada- Swafford