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Symphony Wave Power is a technology that converts the internal pressure variation in a water wave into electrical, renewable energy.
The technology of Symphony Wave Power is
The principle is based on “point absorbing theory”
gaining large amount of energy by small devices.
Under a wave top the device moves down. Under a wave trough it moves up. During this motion it presses the liquid from the membrane, through the turbine into the spring chamber. The turbine moves the generator and produces electricity.
300% to 500% more efficiency compared to non-resonant systems. Like the video explains. The system is a damped mass spring system. The interaction of the waves with such a system is described by Budal and Evans in the seventies of the 20th century, and well documented in wave energy theory.
To be resonant with the waves the natural period of the device must be tuned to the wave period. This is done by changing the (pneumatic) spring in the system.
Short video (gif) of computer simulation with time domain model
Once the wave energy is captured in the motion of the hull, it is taken from that motion by a turbine between the outside rubber roll membrane and the internal spring as the liquid is pushed from the roll membrane to the spring chamber and back.
The black line shows the wave pressure, the blue line the motion of the device. Even with low waves it makes a more or less constant cyclic motion.
The core and the hull
The rubber membrane contains many functions and therefor limits the need for many vulnerable other parts.
The bidirectional Turbine is a special for the purpose developed and patented technology, that has been tested over more than three years.
The e-box is positioned outside the system on the seabed and contains all electronic equipment. The box can be lifted from the seabed, for inspection, commissioning, or updates without removing the devices.
Symphony wave Powers was designed, with the experience of developing previous operations from wave and tidal equipment Here lessons were learned on how to value the importance of an easy installation technology.
As the units are much smaller, small multipurpose vessels or even other small ships can be used. There is no lifting capacity needed. Just a small crane to handle equipment on board into the sea. The technology used to install, is a pull-down technology. With special subsea drilling or screwing equipment an anchor pole is installed in the seabed. This pole and a special pull-down mechanism is used to pull down and lock the SWP device. Later after the starting up of the system, the e-box is lowered and fixed to the seabed.
Lifting the system from the seabed is done in reverse. Even the achoring poles can be taken out of the seabed and no harm is done.
Althought the operation is relative low cost, the nececesity to do it, should be limited. In the beginning the device will be lifted every seven years, for inspection and servicing. A full maintenance and operation plan is available. And all cost are taken into account to limmit the O&M part of the product. The intervals are going to be longer in time as experience is build up. Until a full 21 years operation with no maintanace appart from inspection. This experience will take the technology through the learning curve. The zero maintenance makes all the difference in bringing down the cost. A full plan is documeted and available for partners.
Invisible & sustainable
The technology of Symphony Wave Power is a novel technology based on more than 25 years of experience in wave and tidal business. The technology is a product of co-creation between science and industry led by Teamwork Technology BV in the Netherlands. It represents the know-how of a network of expertise over Europe and beyond. Developed with public support, including from the European Commission, and with the expertise of the offshore industry.
The Symphony Wave Energy Converter (WEC) technology is robust enough to survive the worst case conditions and sophisticated enough to convert wave energy into electricity in a highly efficient way
The working principle of Symphony can be explained shortly as a device with an internal spring that resonates at the wave frequency. Even small waves will attenuate the Symphony motion up to the full stroke. The generator damps this motion by extracting electrical energy.
The system is placed ca. 6 meter under the still water level and will experience a pressure field under the wave crest. This will push the outside hull down and compress the air inside. Under a wave through the air will expand and push the outside up again.
If the natural frequency of the system is close to the wave frequency, it will be able to abstract energy from a larger area than its own diameter. This is called point absorption in wave energy literature. This phenomenon has been studied extensively, but not many devices have been able to apply it, also because it is potentially destructive: as the device charges itself with energy, it will hit the mechanical endstops and destroy itself. In Symphony Wave Power, the endstops are integrated in the shape in which the membrane rolls. This gives the endstop the characteristic of a stiff spring – a buffer that not dissipate the energy, but returners it into the system. By doing so, it causes a small delay which lowers the intake of energy.
Inside the Symphony is a double-acting structural roll membrane. Inside this membrane is a liquid. This liquid is pressurized by the gas on top of the liquid. As the gap from the upper membrane is larger than the one from the lower, the liquid moves in and out of the pressure chamber as the hull moves up and down. As the air volume decreases, the pressure increases. This increase gives a higher force on the membrane and drives the hull upwards once the pressure in the wave pushing on top of the device decreases. This causes the hull to start moving up. The air volume together with the membrane acts like a spring, which must be tuned well according to the mass. This is done by the size of the air volume, making the device resonate at the dominant wave frequency. Looking at the time series in the graph shown above one can see that the device moves at its full stroke, even on low waves. During this motion, the energy captured is calculated by the force of the wave times the stroke. In this way power can be converted even from low waves.
Simple Design developed with partners in the marine industry and support of the EU and Portuguese subsidies.
Aplications: stand alone , in arrays to support Islands and coexistence with offshore wind and Tidal
Symphony wave power is designed to be applied in arrays with a minimum of 6 devices. But of course there is a market for stand-alone special purpose applications as well. In these cases the E-Box gives an underwater stabilized AC grid for applications needed.
Symphony Wave Power is an invisible source of energy. It has zero visual impact as the buoys are placed in arrays (of 6 or more buoys) underneath the water surface, requiring 20 meter of water depth. The arrays require verry limited space. As the energy transition is speeding up not only pricing, but also the availability of space and location is becoming more of an issue.
The artist’s impression shows the possibility to share the grid infrastructure in coastal areas between offshore wind turbines and Solar. SWP, makes better use of the limited ocean space through MUS solutions (Multiple Use of Space). In addition to operational advantages and cost reduction, this limit further restriction of areas for fishery and other shipping.
A promising combination to share the infrastructure is possible, as indicated in the artist’s impression. In even deeper areas floating wind turbines can be co-located with underwater arrays of Symphony Wave Power devices. Also, energy storage becomes more and more crucial. Also the production of this green hydrogen may play a crucial role for the energy transition in the next years. Symphony will therefor develop a wave converter specifically suited to produce hydrogen at off-grid locations.
Symphony can be scaled for different wave climates, but also for deeper seas and combination with other marine technologies
Symphony Wave Power BV is planning to extend its product portfolio in the future. First with a larger Ocean Version, second with hydrogen production and storage units in order to increase stability of electricity delivery.
Currently the protype is undergoing tested. The North Sea version is designed for relatively low and short waves and requires a water depth of 20 meters or more. Later, the technology will be extended to develop an Ocean version.
In our newslater we share news and more information about the technology
and testing results of the Symphony Wave Power.