After years of unsuccessful experimentation, wave energy may finally be emerging from its becalmed state. In Monterey Bay, CA, in the US, last month an experimental power buoy was recovered to test how well storms had been weathered. For 4 years engineers have been checking and rechecking how their technology and the efficiency of their buoy can be improved.
At 8 feet diameter, the big buoy hangs its wave power converter while a heavy and expensive 12 foot plate holds the structure below that, in order to provide resistance for pistons in the converter. Linear motion from the waves drives the pistons to create between 300 and 1000 watts, depending on wave size, from calm to storm conditions. The buoy has to be anchored to the sea floor and now has flaps to help prevent storm stress on the structures. This buoys future is likely to be in powering undersea research equipment and robots (instead of battery power), while the general aim of research elsewhere is to create “farms” of wave power buoys to supply onshore needs through the electricity grid.
Sweden, with research centred on its KTH Royal Institute of Technology,has scaled up wave power in CorPower Ocean AB’s new gearbox system in Stockholm. Using the latest gearbox design, 5X more energy per ton is generated than in previous wave power systems at less expense (one-third the cost.)
It is the cost of generating electricity that has caused most wave power projects to collapse. In Ireland and Scotland (as in Aquamarine Power’s buoy here,) the Atlantic has been harnessed, but failed to provide the expected profit. Reliable energy production is already a problem with variable wave activity, solved in part now both in Monterey and in Sweden. The point absorber system of the CorPower converter is derived from cardiology. Stig Lundback’s heart pump design inspired the conversion of all wavelengths of wave. Over to Norway, in Trondheim’s NTNU, where phase control uses compact buoys to swing in resonance with powerful surges, and tests in France and Portugal. These tests confirm that the timing of both buoy and incoming wave can ensure a new rack and pinon drivetrain (just like your car’s steering) will accommodate absorb the energy of all waves, from crest to trough, thereby increasing the efficiency by a power of 4.
High velocity and heavy loads are capably handled by the numerous pinion wheels, although lubrication will be critical in development. The buoys in Sweden are light and compact with the obvious lower cost a major factor. It is envisaged that a wave energy park of 100 buoys could generate up to 30MW (Therefore each buoy is capable of at least 250KW.) We all look forward to November 2015, when a small scale demonstration in the Atlantic (presumably Iberia) will cooperate with an electricity company, Iberdroia.