Islay’s LIMPET – generating electricity for the grid for over ten years
Wavepower is usually regarded as an infant, experimental technology yet on the island of Islay a shoreline wave energy converter has been generating power for the national grid since 2000. The Limpet (Land Installed Marine Powered Energy Transformer) uses an oscillating water column technology developed by Inverness-based developers Wavegen, a subsidiary of Voith Hydro.
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How an oscillating water column device works
The wave surge forces water into a chamber, where the oscillating water column created by the waves compresses the air column above it, causing rushes of air to be drive through the turbine.
The basic components of an OWC are no more than a chamber vented to the atmosphere and a turbine connected to a generator; the animation on the right shows these components in action:
The chamber of the LIMPET is an inclined concrete tube with its opening below the water level. As external wave action causes the water level in the chamber to oscillate, the variation in water level alternately compresses and decompresses the trapped air above, causing air to flow backwards and forwards through a pair of contra-rotating turbines.
Islay’s LIMPET is the world’s first commercial wave power device to be connected to the UK National Grid. Built in 2000, it is located at Claddach Farm on the Rhinns of Islay. The device was developed by Wavegen in cooperation with Queen’s University Belfast. The capacity of LIMPET is 500 kW. Availability levels now match other, more established renewables, and even traditional power plants, with 2010 figures running at 98%. The plant has accumulated over 60,000 grid connected generating hours, providing a wealth of data to optimise plant performance, and giving clients enormous confidence in long term reliability.