Machines

New Australian project examines whether renewable energy machines can be used to protect coastlines – pv magazine Australia

That doesn’t mean projects have to be paid for by taxpayers, the professor adds, there are many different financial models that could be used – but it does mean governments have to make the call.

Real Wave Energy Case Study

Since its inception, many trials have been conducted to connect wave energy converters to grids around the world. Many of them have managed to generate electricity, but none have stood the test of time.

That is, all but one important exception: where the technology has been used for coastal protection. In the Basque region of northern Spain, the port of Mutriku was regularly damaged in storms before it built its wave energy infrastructure. The Mutriku project looks like a modified seawall and Professor Manasseh is quick to point out that this is not the design the Australian research project will be looking at.

But why he thinks it’s important is firstly because the trial uses technology in a dual way, for protection and power generation, and because it’s about an example of a wave energy project realized with government support.

Resonance

A far cry from blunt wall technology, Australian researchers are studying the use of a physical principle called resonance to quell the force of storm waves.

Before diving into this concept, construct a mental image of a beach in which twenty or so floating shapes from submerged machines are evenly spaced parallel to the shore. They are not connected, there is no wall or netting between them.

We can now return to the rather poetic notion of resonance to explain how individual objects floating in the ocean might be able to stop the waves.

Carnegie’s CETO 5 unit is towed to site for installation at the Perth Wave Energy Project on Garden Island

Government of Western Australia

The oceans have their own frequency; like a pendulum or seesaw, it swings back and forth at a unique rhythm. Most wave energy converter designs in the world take advantage of this. Engineers can tune wave energy converters like giant musical instruments to have about the same natural rhythm or frequency as the ocean swell, says Professor Manasseh.

“When these frequencies are similar, the movement of the machine becomes very important. It’s like pushing a child on a swing: we instinctively only push when the swing comes to an end,” he adds. “The arc through which this resonating swing then travels can become very large, and certainly larger than the distance you extend your arms.”

“Similarly, the resonant wave energy converter moves far more than the water around it, representing wave energy extracted from an ocean area much larger than the physical size of the machine.”

By using resonance, converters maximize the energy they draw from the wave. The other side of the coin is that by dropping the machines slightly out of resonance, it would be possible to deflect the waves by breaking their rhythm.

“Spaced the right distance, [the machines] can work effectively as a wall without touching.

The key word is control

“The word: control is integral to what we do,” says Professor Manasseh. That is to say, controlling a fleet of machines well enough so that they are used for two radically different purposes.

“When there’s a storm with disaster potential, you probably don’t care about generating power at all during that time, so you can potentially run these machines in a completely different way where you don’t you’re not extracting energy from the waves at all, but you are deflecting the waves.