Ocean waves are an abundant and untapped source of renewable energy with less variability than wind or solar power. Research into this growing sector is gathering momentum at the Australian Maritime College thanks to national funding of two key projects.
The first project, supported by a $256,000 Australian Research Council grant, is a partnership with Perth-based company Bombora Wave Power to conduct physical scale-model experiments on its wave energy converter. The first round of trials took place in AMC's model test basin in November.
AMC Associate Professors Irene Penesis and Gregor Macfarlane said ocean wave energy offered great value to future electricity markets and realising its potential was a huge opportunity for Australia.
"Wave energy is an untapped resource and Australia's got the highest potential in the world. If we're not tapping into this resource we're doing something wrong," Associate Professor Penesis said. "The idea is to be able to test this device at different wave lengths and wave heights, and also at different water depths, to try to see where it would be best placed in the ocean environment."
Bombora director Shawn Ryan said he was optimistic the design would lead to a commercial venture. There are several companies developing and trialling wave energy converters in Australia, but so far they have not progressed to large-scale operations.
"There hasn't been anyone yet who has cracked the nut in terms of making a commercial product – we hope to be the first," Mr Ryan said.
"We think we've solved the issues of the predecessors that have gone before us. The key criteria we looked at was survivability, so you've got to survive those large storm events that have highly energetic sea states, and cost of electricity is the dominant consideration."
The device is a seabed-mounted structure with a flexible membrane that enables it to withstand storms and harness a greater proportion of the available wave energy. The system's flexible membrane and simple valving squeezes air through a closed circuit and extracts energy with a central air turbine to generate electricity.
Mr Ryan said each unit was rated at 1.5 megawatts and had the potential to supply renewable electricity to 500 homes, equivalent to producing one gigalitre of desalinated water each year or taking 825 cars off the road.
The testing device is made from fibreglass but the full-size converters will be built from concrete and weigh up to 1000 tonnes. The results from the model test basin trials will help determine the device's optimum size and shape.
Bombora hopes to have commercial prototypes operating within six years. The second project is a collaboration between AMC and Swinburne University of Technology to develop modelling on the performance of wave energy farms. Researchers will focus on identifying the impact of wave energy converters on each other and the impact of current flows around a converter. The project is funded through a $770,000 grant from the Australian Renewable Energy Agency.
"Wave power is an emerging sector and most technology trials involve individual or few devices. Once proven, more devices could be installed in arrays or farms," Associate Professor Penesis said.
There hasn't been anyone yet who has cracked the nut in terms of making a commercial product - we hope to be the first
"The nature of the sea means these wave energy devices may have a noticeable effect on each other. For example, an array of devices could act together as one collective machine with significantly different behaviour to a lone device. This collective behaviour is currently not well understood and we are aiming to fill this knowledge gap."
Mathematical modelling and laboratory experiments will be used to predict the performance of small arrays of wave energy devices. The modelling software could be used by communities, state and federal governments to assess impacts of developing the ocean wave energy resource in a particular area. "This research will give industry and investors an impartial assessment of the performance of wave energy farms and provide greater confidence when negotiating large developments," Associate Professor Penesis said.
"It may also uncover the best arrangements for the devices to provide optimum performance."
The project is supported by Australian wave energy companies BioPower Systems and Carnegie Wave Energy with additional cash.