Energy from ocean waves

Figure 1. The Pelamis Prototype machine off of the coast of Scotland (2007).[1]

People have recently been able to start harnessing energy from ocean waves, but could be a very promising primary energy source. Anyone who has been on a beach with large waves has a sense of their raw power, and this power can be transformed into electricity. Waves are caused by winds blowing over the oceans, where the kinetic energy from the wind is transferred to the water. This energy can build up gradually over long distances, and can be harnessed closer to the shore.[2]

Various devices have been developed over the recent decades, one of them being the Pelamis as seen in Figure 1. It is placed facing the oncoming waves, and bends in response to their contact. The bending is resisted by hydraulic devices which pump high pressure fluid through hydraulic motors, which drive electric generators. The electricity generated is then fed towards the shore and can provide power to those living there.[2] It could also be transmitted inland, effectively powering a small coastal country or nearby towns.

Three of these were put into testing in 2008 off the coast of Portugal. They were 180 meters long consisting of 4 units, each rated at 750 kilowatts with an estimated capacity factor of 25-40%.[2]


  1. Wikimedia Commons [Online], Available:
  2. 2.0 2.1 2.2 B. Everett, G. Boyle, S. Peake and J. Ramage, "Wave power," in Energy Systems and Sustainability, 2nd ed., Oxford, UK: Oxford, 2013, ch.14, pp.608