Great potential with great challenges

Wave power is a concentrated form of renewable energy that comes from the friction between the water surface and the wind. The energy is built up by the wind on the open seas and then transported to locations closer to the shore, where it can be extracted. Wave power can generate a high power output in relation to sea area and the average energy content changes more slowly and predictably compared to, for example, the wind.

The greatest challenge for wave power is the highly fluctuating energy in ocean waves which cause very high input peak loads into the Power takeoff (transmission). Peak loads are in the order of 10 times higher than the average load. This necessitates a high degree of oversizing of PTO and electrical components and also reduces the efficiency in the energy conversion, if the peak loads are allowed to propagate into the system. Oversizing of components and low efficiency are two key reasons for the high cost of power experienced in the wave power industry so far.

It is essential to smooth the captured energy in the power takeoff in order to reduce the cost of power and to provide a continuous power output suitable for the grid. The mechanical power smoothing technology developed by OHT has superior capabilities compared to for example hydraulic systems: Very high average efficiency in the highly fluctuating energy and changing sea states over the year, (ii) Constant torque system with very little need for oversizing, (iii) provides sufficient storage capacity to smooth power over several following waves.

Technology status

At present, there are no commercial technologies available. Various types of wave power devices are being developed and a few pilot devices are being tested. The most advanced projects in terms of experience and commercialization include: Pelamis, Aquamarine Power, Ocean Power Technology, Voith Hydro Wavegen, Wave Dragon, Wave Star Energy, Oceanlinx and Seabased. Many wave power developers and power companies are locating activities in UK and Portugal where the political support for wave power is high, and where the wave energy resources are abundant.

When commercial, wave energy converters will be installed in large wave farms, approx. 100-200 MW or larger. There can be consider­able synergies when combining wave power with wind power in locations suitable for both technologies. Wave and wind power do not compete for the same resources and the wave energy is delayed compared to the wind energy. When combined, the power production of the used area and the utilization of the power transmission to the area are greatly increased, which in turn reduces the cost of power for both technologies.

Wave energy roadmap

According to the European Ocean Energy Association, the theoretical potential for wave power is 45 000 TWh annually. This is in the same order as the global use of electricity. The European ocean energy roadmap was published in 2009 to map out the potential development of ocean energy up to 2020 and beyond to 2050. By 2020, 3,6 GW (9 TWh) of Ocean Energy (Wave, Tidal and Osmotic) can be expected in Europe, creating 40 000 jobs. The required investment for installing this capacity has been estimated to 8,5 billion Euro.

By 2050, the numbers are 188 GW (645 TWh), with an estimated investment of 451 billion Euro. Creating 471 320 jobs.