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Wave power


Breaking wave

Could wave power provide over a quarter of our current energy needs? (Source: iStockphoto)

As fierce storms wrecked the ship the Pasha Bulka off the New South Wales coast last year, one Australian company was breathing a sigh of relief.

The prototype wave power device owned by Oceanlinx that sits off Port Kembla was unscathed by the storm, one of the biggest threats to wave power devices.

"That was a pretty good test of it," says chief technical officer Tom Denniss of Oceanlinx.

Wave power has been the quiet cousin in the renewable energy stakes, long eclipsed by solar, wind and even tidal energy.

However for the past couple of decades companies all over the world have been quietly beavering away, trying to find the magic key to take the energy inherent in wave movement and turn it into an emission-free, renewable source of power.

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Movers and shakers

Progress has been made. Portugal has what is being touted as the world's first wave farm and there are hopes that the wave-licked shores of Australia could follow suit in just a few years.

"There is a growing feeling that the technology can be successful," says Andy Baldock a UK wave energy analyst from engineering firm Black & Veatch.

Research into wave power started around 20 years ago he says, originating in high-population, energy-hungry places like the UK and Europe that have few natural energy sources.

Progress continued in wave-like spurts and lulls until recent times when the more urgent push for renewable energy sources stoked research and development funding.

"There's a phenomenal number of [wave technology] devices out there, with several thousand patents. Over 100 ideas have been actively pursued, of which around 50 have had a reasonable amount of work done on them and around 20 are still being pursued quite seriously. At least ten are planning to do near full scale prototypes," says Baldock.

And Australia is well placed to tap into the potential of this renewable energy source.

Tidal vs Wave powerAlthough both tidal and wave power rely on water to create power, they use it in very different ways.

Tides are the result of lunar forces, with water pulled by the gravitational force of the moon. The tide comes in, and then goes out. Tidal power systems typically work by capturing the high tide when it comes in using a barrage system across a river mouth. As the tide recedes, the captured water is funnelled through a turbine system which creates electricity.

Waves, on the other hand, are caused by winds whipping across the ocean. Wave power systems try to use the motion caused by waves to generate power.

Of the two, wave power is the larger resource, with some figures putting its potential energy capability at twice the world's current use. However tidal power, just like the tides, is more predictable.

"Waves are caused by wind blowing over long stretches of water, and [that wind] gets stronger towards the poles," says Baldock.

"That means that Australia and New Zealand have got good resources, as well as northern Europe, Canada and northern USA."

A recent report by RPS MetOcean, commissioned by Carnegie Corporation, one of the Australian companies looking to launch wave power technology, suggested that Australia had a near-shore wave energy resource of 170,000 mega watts, or around four times the national installed power generation capacity.

Even if only 10 per cent of that potential power was extracted, says Carnegie, it would supply 35 per cent of Australia's current power demand.

"Waves have a lot of energy," says Carnegie CEO Dr Mike Ottaviano.

"Wind can be a large resource, but it is only around some of the time. Waves are [at some sites] 100 per cent of the time. The swell height or wave energy comes from the south-west, so the most exposed places are going to be south-west WA, Tasmania, parts of Victoria and southern South Australia."

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Harnessing the ocean

However it is the power in waves that has made using it such a difficult proposition.

"The big problem with most wave technology is that waves have too much energy," says Matthew Warren from the Clean Energy Council Australia. "So when you get storms, they can be highly destructive.

"Water is like air, but denser. Cyclones are no good for wind turbines, and the ocean is like that all the time. There's this huge barrage, and [the technology] has got to be strong enough to weather the storms.

"The ocean floor is a safer place to be than the surface, but everyone is trying to solve the problem in their own way."

A recent Australian government research paper on the potential for renewable energy to provide baseload power in Australia came to a similar conclusion: "The fact that there are many different [wave power] concepts under investigation in various countries… suggests that the best technology has not yet been identified."

Three companies in Australia now have well-regarded prototypes to tackle the difficulties of wave power.

Oceanlinx has its pilot wave power units off Port Kembla in NSW, floating on the water's surface. As the wave passes, the waterline in an open chamber moves up and down, displacing the air inside. That air is then pushed into the unit's built-in turbine, which creates energy, which is then piped back to shore.

The BioPower Systems pilot unit to be deployed in the King Island, Tasmania late in 2009 is fully submerged and tethered to the sea floor. As it oscillates back and forth with the waves, that motion creates power, with each unit capable of generating 250 kilowatts of power.

Carnegie Corporation is developing the third wave power solution in Fremantle, Western Australia. Unlike the other two projects, electricity generation happens onshore, rather than in the water. As the waves pass over it, motion pushes water into the system which it is pumped onshore into a generator. The water pumped ashore can also be used for desalination.

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Making the waves pay

What stands in the way of wave power now is not science but economics. All three companies have stated intentions to have commercial wave farms up and running within two to three years. Success depends on their ability to compete with Australia's other, cheaper energy sources such as coal.

"Australia has had less incentive [to go renewable] because it has such an abundance of energy resources," says Warren.

"Most of this technology is more expensive than existing energy resources. There's limited info and a lot of promise, but the question will be how it comes around.

"If it were easy, we would have been using it 100 years ago."


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Published 23 February 2009