July 4, 2008 A giant rubber tube known as the “Anaconda” may present an viable solution to the challenge of generating electricity from the power of ocean waves. Under development in the UK, the simple design means it would be cheap to manufacture and maintain, resulting in clean electricity at a lower cost than other types of wave based energy production.
Not to be confused with tidal power, which draws on the ocean’s currents, wave power refers to the energy of surface waves in the ocean and the harnessing of that energy. To date, cost has been a key barrier to the mass deployment of standard wave converters. Traditionally wave energy devices have been made from metal and incorporate expensive hydraulic rams, hinges and articulated joints. Being made from rubber reduces the capital and maintenance costs and scope for breakdowns of the Anaconda.
The cheap-to-make Anaconda is long and thin in shape, and closed at both ends and filled completely with water. It is designed to be anchored just below the sea’s surface, with one end facing the oncoming waves. When a wave hits the end it squeezes the device, causing a “bulge wave” to form in the tube. The bulge then runs through the tube while the wave that caused it runs along the outside of the tube at the same speed. This continues to squeeze the tube and makes the bulge wave bigger. Finally, the bulge wave turns a turbine fitted at the end of the device and the power produced is fed to shore via a cable.
Still in the early stages of development, the concept has only been proven in a lab at very small scale. The next step is a program of larger-scale laboratory experiments and mathematical studies designed to estimate how much power a full-scale device would produce. The experiments will use tubes of 0.25m and 0.5m (0.8ft and 1.6ft) in diameter to assess the Anaconda’s behavior in regular, irregular and extreme waves.
The full-scale Anacondas will measure 200m x 7m (656ft x 23ft) when built and be installed in water depths of 40-100m (131-328ft). The engineer’s initial assessments indicate that it 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 6 pence (US$0.12) per kWh or less. Despite the cost being almost double that of electricity from coal-fired power stations, the price is cost-competitive with other renewable energies.
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