Anaconda wave-power generator snakes into next stage of production

The device is said to be at the forefront of a new generation of wave-power machines that could slash renewables costs

Alok Jha, green technology correspondent
guardian.co.uk, Wednesday 6 May 2009 00.05 BST

Giant rubber sea snakes could harness the plentiful clean power off Britain's coasts within five years, according to the inventors of a new type of wave-energy generator.
Yesterday, Checkmate Sea Energy unveiled the final stages of a proof-of-concept trial of its Anaconda device, seen by many experts as at the forefront of the next generation of robust, cheap wave-power machines that could slash the costs of making renewable electricity.
Made from a composite of fabric and natural rubber, the Anaconda rides oncoming waves and uses the motion to drive a turbine in its tail. The test device is nine metres long but its developers say that a full-scale device could be up to 200m in length and be capable of producing 1MW of power, enough for a thousand homes, and cost £2m to build. Farms of 50 or more could be placed underwater a few miles from the coast.
Harnessing wave power could contribute significantly to the UK's target of sourcing 15% of its energy from renewable sources by 2020. The Carbon Trust found that wave and tidal stream technologies could add 10-20GW of electricity capacity to the UK by 2050, in particular from areas such as north-west Scotland and south-west England.
"It's a completely new kind of wave power machine," said Rod Rainey, a chief engineer with engineering design consultants Atkins and inventor of the Anaconda. "The beauty of wave energy is its consistency. However, the problem holding back wave energy machines is they tend to deteriorate over time in the harsh marine environment. Anaconda is non-mechanical: it is mainly rubber, a natural material with a natural resilience and so it has very few moving parts to maintain."
Each Anaconda device is tethered to the sea floor and positioned head-on into the coming waves. Floating under the sea surface, the water-filled rubber tube swims with the waves – as a swell hits the front of the device, it creates a bulge that travels to the back of the tube, in the same way a pulse of blood travels along an artery. When the bulge wave reaches the Anaconda's tail, the energy is used to drive a turbine and create electricity.
"Wave power has always been the poor relation of wind energy, but a lot of people are resentful of wind turbines on their doorstep, or in vast tracts of coastal waters," said Paul Auston, chairman of Checkmate. "What we're offering […] is a new technology which you can't see, it's under the water so it's not as intrusive and it's made of a natural material."
The device has already been given a significant vote of confidence by the Carbon Trust. The Anaconda has been chosen as one of only two technologies to take part in the Trust's marine accelerator programme, which aims to push new low-carbon technology ideas closer commercial reality.
"We were attracted to it because of its simplicity – in theory it's just a rubber structure," said the Carbon Trust's Stephen Wyatt. "It has the potential to be robust and quite easy and cheap to manufacture. When you look at some of the severe offshore conditions that wave and tidal devices have to face, then we realise that a structure this simple could be quite cheap."
Their analysis of the technology concluded that, because of this simplicity, Anaconda could create a "step-change" in how soon wave devices became commercial. Their research showed that, while wave energy in general costs around 25p per KWh to make, the anaconda had the potential to bring prices down to around 9p per KWh. Mains electricity today form fossil fuels costs around 6p per KWh.
Marine energy devices that are nearing commercial reality today include the SeaGen and Pelamis, a tidal and wave generator respectively. Both went into trials in the sea last year, SeaGen in Strangfod Lough and Pelamis off the coast of Portugal. Like Anaconda, Pelamis also uses a snake-like motion to capture wave energy by flexing its articulated metal sections on the sea surface. Both devices have had technical problems however, mainly due to the harsh conditions at sea.
The Anaconda's designers stress that its key advantage is its survivability. "If the worst comes to the worst it'll only be washed up on the beach, and you can patch it up and put it back out there," said Rainey.
The proof-of-concept trials have been carried out for the past few weeks in a wave tank defence company QinetiQ in Gosport, Hampshire. When these are complete, Checkmate hopes to build a quarter-size version of Anaconda for possible sea trials. If all goes well, the Checkmate thinks the first devices in commercial production could be floating in the seas off Britain as early as 2014.