Using ocean waves to power the electrical grid
Author Nicholas Derenzo Illustration Jameson Simpson
Benjamin Franklin famously quipped that the only certainties in life are death and taxes. When it comes to renewable power, the Australian company Carnegie Wave Energy says the only certainties are the tides. Solar and wind sources, after all, can be disrupted by cloudy and breeze-free days, respectively. That’s why the Perth-based innovators have devised a method to effectively and efficiently harness the massive energy potential of the reliably gnarly waves breaking off the coast of Western Australia. The company recently debuted the world’s first grid-connected wave power system, CETO 5. Named for the ancient Greek goddess of sea monsters, the system employs three simple steel buoys that bob just under the surface of the Indian Ocean, about two miles from the HMAS Stirling naval base on Garden Island. Here, a step-by-step guide to the next wave in green electricity.
1. Tethered to pumps on the seafloor, the three 36-foot-wide steel buoys are filled with seawater and foam so that they’re just buoyant enough to float about three to seven feet beneath the surface of the water. By keeping the buoys slightly submerged, the system’s designers protect the machinery from the corrosive effects of sun, wind and storms. Even better? No unsightly machinery visible from the beach.
2. When a wave crashes and the buoys bob, the seabed pumps are activated, and water is thrust at high pressure through a subterranean pipe to a power station on land. The surging water, in turn, spins hydroelectric turbines that activate a generator, providing the naval base with 5 percent of its electricity. Because the water is being forced into the power station at such high pressures, it can also be desalinated through reverse osmosis, bypassing the costly fuel and electricity usually needed to power such a process.
3. By 2017, the organization plans to unveil the three-megawatt, 66-foot-wide CETO 6, which will be 12.5 times as powerful as the current 240kW iteration. The next generation of buoys will generate their own electricity without the need for a power plant back on land. Since it will be fully self-contained, CETO 6 can be moored much farther offshore, where the waves are even stronger. Instead of a subterranean pipe to carry pressurized water, all the system will need to power the grid is a very, very long extension cord.