Other solutions


Australian Carnegie Clean Energy is perhaps the company that has made the most progress in terms of wave power. The concept consists of a large, relatively flat buoy anchored to the seabed. The buoy is pulled down below the surface so that it is not exposed to the full power of the waves. Waves passing over the buoy causes pressure differences that will move it up and down. This is used to pump water through a turbine which drives an electric generator. The water pressure is also used to desalinate seawater. The development has been ongoing since 1999, with several prototypes. Buoy size is crucial for the energy yield. The sixth, and most recent generation, Ceto 6, has a buoy diameter of 20 meters and an expected capacity of 1 MW.

Swedish Seabased commercializes research carried out at Uppsala University. In 2008, the production of wave power generators started at a factory hall in Lysekil on the Swedish west coast. A 800 x 800 meters large ocean area outside the island Smøgen was allocated for the wave power plant and a 10 km long power cable was brought ashore. By 2017, 40 turbines with corresponding buoys were in place. The target is 100 units with a total power of 10 MW. The generators are of linear type standing on concrete slabs on the seabed. A buoy at the surface moves the translator (equivalent to the rotor in a normal generator) up and down via a strong rope.

Swedish Waves4Power has its headquarters in Gothenburg, but builds and tests its idea in Norway. In the years 2015-16 the concept was tested outside Runde Miljøsenter near Ålesund on the Norwegian west coast. The principle is a wide buoy built around a long (35 m) water-filled tube. A piston in the tube is forced to move up and down when the buoy is affected by waves. The piston is connected to a hydraulic system which drives an electrical generator. Current from the buoy was taken into the Norwegian power grid on June 2, 2017. The plan is to start production at Fiskåholmen in the municipality of Vanylven not far away.

Norwegian Havkraft has developed a concept based on the principle "swinging water column". A floating platform contains a variety of vertical tubes of different diameters, all open at the bottom, and connected to a pipe system on the top. Waves cause the water level in the vertical pipes to rise and sink. This pumps air in and out of the pipe system. Turbines convert this motion to rotation that drives generators. It will also be possible to mount a wind turbine on the platform. In the period 2014-16, the principle was tested in a converted fishing boat, which for periods was anchored near Stad, the weather-beaten stretch of water, on the west coast of Norway.. The company signed its first commercial contract in 2017.

Ocean Power Technologies, based in the US, has developed PowerBuoy. It is smaller, but similar to the Waves4Power buoy, discussed above. The difference seems to lie in a so-called "heave plate" at the bottom of the vertical inner tube, which is also narrower. The heave plate inhibits vertical movement of the tube when the outer ring-shaped buoy moves up and down with the waves. A system of hydraulic cylinders drives a generator which charges a battery pack. The system can therefore deliver even current, also when there are no waves. The company is selling one product, the PowerBuoy 3 (PB3). The ring-shaped outer buoy has a diameter of 2.7 meters, the inner tube 1 meter. The depth is 10.8 meters and the weight 10 tonnes.

Finnish Wello has developed a buoy with a built-in asymmetrical weight that swings around a vertical axis when the buoy moves in the sea. This drives an electric generator. Wello has built a one MW buoy which has been tested at the European Marine Energy Center (EMEC) in the Orkney Islands repeatedly since 2011. In 2017 a business group led by the Finnish energy company Fortum received a grant of 17 million euros from the European Commission's Horizon 2020 program for a five-year development project. Practical open sea testing and networking will take place at the WaveHub test center in Cornwall, England.

Israeli Eco Wave Power produces a system of hinged floaters attached to shore-based or floating installations. The movement of the floats is transferred to a fast-moving generator by means of a hydraulic system with accumulator tanks. They have developed a pilot plant in Jaffa in Israel and a the first stage of a commercial plant in Gibraltar, where they are now supplying power to the grid. At a former World War II Ammunition Jetty, sits the initial 100KW of a 5MW power station. Upon completion of the whole 5MW, this site will provide Gibraltar with 15% of its overall consumption of electricity.

These are some examples of other technological solutions in play today. The history of wave power, however, contains many other trials, but all seem to be abandoned today.