Wave power
Wave power plants are a form of small hydropower plants. They use the energy of ocean waves to obtain electric current and are among the renewable energies. Realized to date systems are prototypes and are used for different tests and trials.
In contrast to the tidal power station tidal range is not utilized to exploit the energy difference between high and low tide, but the continuous wave motion.
Potential
The energy released on impact of waves on a cliff performance is on average 19 to 30 kilowatts per meter of coastline; the waves on the high seas to reach the best places (eg the northeast Pacific, the northeast Atlantic Ocean, Cape Horn, Pacific Ocean south of New Zealand) up to 100 kW per meter of wave roller. In the inland seas ( Mediterranean, Baltic Sea ), the values are only about one-tenth that of the oceans. On the basis of data collected by buoys in many places of the seas and oceans for decades values of wave height and period ( time between the arrival of a wave crest at a point up to arrival of the next wave crest ), the wave energy available for the location of a wave power station in advance can be estimated.
So far does the ripple current in production up to ten cents per kilowatt hour. The price is about twice as high as that of wind power. The first commercial wave power plant in the world with an output of 300 kW was taken in the port city in northern Spain Mutriku of the utility Ente Vasco de la Energía in operation.
Principles of Operation
The use of wave energy is possible with different principles:
- Pneumatic chamber: use of incoming and outgoing air in a chamber in which the water level by a connection to the sea lifts and lowers, by a wind generator.
- Relative motion of floating bodies - so-called Sea Serpent - to each other or to the banks. The movement is usually implemented by means of hydraulic systems that drive the generator.
- Use of the potential energy ( energy level ) accrued waves on a ramp ( project Wave Dragon)
- Terms of rising sea floor off the coast in water depths of 8-23 m (Project WaveRoller )
- Movable panels, gates or fins
Pneumatic chamber
A first wave power plant based on the principle OWC ( Oscillating Water Column English, German: oscillating water column) is since 2001 on the Scottish island of Islay for testing purposes in operation and dined for the first time so that current in a commercial power grid. It was built by the Scottish company Wavegen. In this type of power plant each wave pushes the water in concrete chimney-like tubes and then pulls it out again at a trough. At the top of the tubes open into turbines. Due to the up and downward moving column of water the air is alternately compressed and sucked into the concrete tubes. This results in the outlet of a fast flow of air to drive a Wells turbine.
The performance of the power plant on Islay ( limpet ) were disappointing in the first years of operation. The originally planned annual average power of 500 kW had, since the effect of a seabed plateau had not been considered in the design can be reduced to 212 kW. Overall, however, only an average power of 21 kW was achieved in 2002. In 2005, Voith Hydro Wavegen and the availability of the turbines could increase it gradually to 98%.
2011, the wave power plant in the pier of the Basque town of Mutriku was put into operation. The plant with 300 kW is the first commercial power plant of this type and is operated by the Basque utility Ente Vasco de la Energía (EVE). It is equipped with 16 wells turbines.
The discontinuity of the energy tax, which varies with each wave, attempts by short-term memory to get at, for example, flywheels. Also, the parallel operation of several similar plants, which are spatially separated, can smooth out the fluctuations.
Buoyancy
→ Main article: Sea Serpent ( wave power )
An ability to utilize the kinetic energy of the waves is converted by an array of mobile, connected by hinges, floating on the surface elements ( carpet). The ocean waves distort the overall structure. In the joints are hydraulic cylinders. By the movement of the working fluid is forced into the balancing cylinder through tubes with built-in turbine and generator. The electricity is uneven, but averages at use of many devices.
A similar design had been the early Salter Duck. Here raises and lowers the shaft, the cam lever an oversized axle.
Pioneering work for several years, the company Pelamis Wave Power of Edinburgh, Scotland. She has developed the " PELAMIS " said project. The power plant is similar in appearance to a snake. Hence the name " Pelamis " (Greek for sea serpent ). 4 long steel tubes and 3 " energy conversion modules " with 250 kW of power result in a P -750 system, which has a rated output of 750 kW. It is 150 m long, has a diameter of 3.5 meters and weighs 700 tons with ballast.
In early October 2007 were the three systems P -750 001, P -750 P- 002 and 750 003 for final tests in the harbor of Peniche (90km north of Lisbon ). In 2008, she was then towed to the north and placed in service before Aguçadoura near Pavoa do Varzim (north of Porto / Portugal).
However, all three plants were shut down in the first quarter of 2009 due to technical and financial problems and towed to the port of Porto. Currently there are no details as to whether it will ever come to re- commissioning.
Following the same principle, a mobile wave power plant has been proposed as marine propulsion and placed on the Internet for discussion since 2005. Mentioned In the "Eco- Trimaran " design set equal to three large moving float to the wave energy on the above-described hydraulic intermediate in electricity. The ship will also use ( windmill ) solar energy ( PV ) and wind energy.
Some buoys designs use hydraulic cylinders.
In an Anaconda mentioned model of sea snake wave power plants, the floating body consists essentially of a rubber-like material. The time required for the production of energy decreases so that in comparison with the existing steel bodies of other models significantly, thereby reducing the yield factor significantly improved, that is the time required for the production of amount of energy is generated in a much shorter time from the installation itself again.
A variant of SRI International uses special polymers (rubber-like plastics) that convert to special buoys the wave motion into electricity.
Ramp
The Wave Dragon project consists of a Wellenkonzentrator that focuses the waves by two v - shaped arrangement barriers towards the center. The thus amplified waves run up a ramp. From there, the water over turbines that drive a generator flows back into the sea. The entire system is designed as a floating offshore power plant and is therefore not bound to the coast. A prototype exists in Nissum Bredning, a fjord in the northern part of Denmark since 2003.
Increasing ocean floor near the coast
For the use of wave force on rising seafloor near the coast, the Finnish company AW - Energy has developed the Wave Roller -called principle. In water depths of 8-20 m- practically vertical, movable metal plates mounted on retractable metal platforms almost at the beach - are. The currents cause these metal plates to move back and forth. A hydraulic system with enormous pressure to produce a torque in a connected hydraulic motor. A generator connected downstream of it electrical energy is generated. About a submarine cable the system to the power supply is connected.
The first of its kind was the summer of 2012 north of the port city of Peniche in baleal off the coast of Portugal in operation. This system consisted of a platform with three moving " plates ". The rated power of 300 kW totaled. Currently run different test series. The number of " plates " varies 1 to 3 anchored along the sea floor, water is outside the fiducial marks - nothing to see from the plants over.
Movable panels, gates or fins
In the Japanese wave power plant " Pendulor " the surging waves crash on the shore on a gate and into an underlying container. When flowing back, the door is moved in the other direction. The movements of the door to be implemented on a hydraulic into electrical energy.
The ship design " Orcelle " owned by Wallenius Wilhelmsen -, an overseas Car Transporter, the wave energy use by approximately horizontally arranged below the hull plates that are moved by the waves each about a transverse axis to the direction of travel. This ship is to use off the energy of the waves, the sun and the wind.
On the other hand moves the realized in Japan catamaran " Suntory Mermaid II " forward only with wave power. However, it can achieve the very modest benefits ( less than walking pace ). Is effected also by means of two approximately horizontally arranged movable plates at the rear, which are moved by the waves to a direction of travel transverse to the shaft.
To a floating flap that is anchored near the coast in a water depth of 10 to 15 meters on the sea floor, it is in the development of the company Aquamarine Power. 2009, a first prototype of this system ( " Oyster 315 " with 315 kW) in the test field Billia Croo of the European Marine Energy Centre ( EMEC ) has been tested in the Orkney Islands. In this type two hydraulic pistons are driven by the reciprocating motion of the valve, pump the water through a pipeline to shore. The high- pressure water drives a turbine here.
Problems
Many of the test plants were destroyed by winter storms that about one hundred times as much promise as the wave motion during the other seasons. Since therefore exist with wave power plants is not yet sufficient experience, you know about the environmental impact, for example on marine life, so far little.