The ‘Anaconda’ is an innovative wave energy concept.

A device consisting of a giant rubber tube may hold the key to producing affordable electricity from the energy in sea waves.

Led by researchers from the University of Southampton, the ‘Anaconda’ is an innovative wave energy concept. The simple design means it would be cheap to manufacture and maintain, enabling it to produce clean electricity at a lower cost than other types of wave energy converter.

Named for its resemblance to the long thin shape of the Anaconda snake, the rubber tube is closed at both ends and filled completely with water. It is designed to be anchored just below the surface of the sea, with one end facing the oncoming waves. A wave hitting the end squeezes it and causes a ‘bulge wave’ to form inside the tube. As the bulge wave runs through the tube, the initial sea wave that caused it runs along the outside of the tube more and more and causing the bulge wave to get bigger and bigger. The bulge wave then turns a turbine fitted at the far end of the device and the power produced is fed to shore via a cable.

Made of rubber, the Anaconda is much lighter than other wave energy devices (which are primarily made of metal) and dispenses with the need for hydraulic rams, hinges and articulated joints. This reduces capital and maintenance costs and scope for breakdowns.

Still at an early stage of development, the Anaconda concept has only been proven at very small laboratory scale. EPSRC-funded experiments are to take place to try and answer questions about the potential performance of the device. Using tubes with diameters of 0.25 and 0.5m, the experiments will assess the Anaconda’s behaviour in regular, irregular and extreme waves. Parameters measured will include internal pressures, changes in tube shape and the forces that mooring cables would be subjected to. In addition to providing insights into the device’s hydrodynamic behaviour, the data will form the basis of a mathematical model that can estimate exactly how much power a full-scale Anaconda would produce.

When built, each full-scale Anaconda device would be 200m long with a 7m diameter, and deployed in water depths of between 40 and 100m.

Initial assessments indicate that the Anaconda would be rated at a power output of 1MW (roughly the electricity consumption of 2000 houses) and might be able to generate power at a cost of 6p per kWh or less. Although this is around twice as much as the cost of electricity generated from traditional coal-fired power stations, which compares favourably with generation costs for other leading wave energy concepts.

Commenting on the project, Professor John Chaplin, from the University of Southampton’s School of Civil Engineering and the Environment, said: “The Anaconda could make a valuable contribution to environmental protection by encouraging the use of wave power.

“A one-third scale model of the Anaconda could be built next year for sea testing and we could see the first full-size device deployed off the UK coast in around five years’ time.”