The race is on to commercialise ocean power, and Australia has a chance to play a leading role, according to Professor Harries.

He says that Australian ocean power technologies are certainly developing in line with their overseas counterparts, or are at least fast catching up.

He explains that there a variety of ocean wave conversion technologies have been proposed, some of which are more promising than others.

“Many ocean wave conversion technologies are in design or under development. They are all different, although there are five generic types, with the oscillating water column (OWC) being the most common in use. Wave energy conversion devices are further classified according to whether they are designed to be installed in onshore, offshore, and far offshore locations. None are yet fully commercialised, although some are getting close, so you could not say that the Australian technologies are followers.”

According to Professor Harries, the Portuguese Aguçadoura 2.25 megawatt (MW) wave energy project is the only commercial wave energy conversion project currently in operation. The project, located in the Atlantic 5 km off the coast of northern Portugal, uses the Pelamis Wave Power technology developed by Scottish company of the same name. The joint venture partners plan to expand the scheme by adding a further 20 MW.

Professor Harries cites the American Aqua Buoy and Power Buoy, the Wave Bob from Ireland and the Wave Dragon, a collaboration of a number of European countries, as other successful technologies currently under development.

Outlining how Australia’s ocean power resources compare with those of other countries,Professor Harries says that the southern coastlines are highly prospective ocean power sites.

As Professor Harries explains, “Wave power resources are linked to wind, which is linked to latitude (wind speeds increase with latitude), with the best wave resources usually being between the latitudes of 40 and 60 degrees. However, it is also linked to the length of the fetch (the uninterrupted distance over an ocean over which ocean waves are being generated by the wind) and due to the long ocean fetch between Southern Africa and Southern Australia, the southern coastlines of Australia have high energy wave resources.

“Energy in waves is a function of, primarily, wave height, wave speed, the distance between the waves (wavelength, frequency or the period) and the density of the water. The energy in a wave is proportional to the period and to the square of the wave height.”

Accordingly, wave speed, wave height and wave length are measured using buoys fitted with recording instruments. Meteorological forecasts are also used to predict wave height.

While the commercialisation of a small number of technologies is only now starting to happen, the first wave conversion technology was patented in 1799 by Monsieur Girard in France, and by the early 1970s around 300 patents had been filled. Since the 1970s, there has been significant progress in the development of a number of wave energy conversion technologies, including some here in Australia.

“Converting wave energy into electricity is not simple,” says Professor Harries.

“The marine environment is harsh. Storms can cause catastrophic damage to wave conversion systems; vessels can cause damage; all sorts of things grow over anything that is put into the ocean; seawater is corrosive. All these things create technical challenges and increase the costs.”

He adds that legal and regulatory issues, as well as difficulties created by placing electric cable underwater, are other challenges faced by the industry.

“Wave farm owners not only need rights of use to certain areas where their generators are located, but rights to prevent other things from reducing the waves, such as ships anchoring offshore in the direction that the waves are coming.”

Moreover, like most renewable energy systems, the operating cost is zero as the wave energy resources are free, but the up front capital costs are high.

Maintenance costs are also likely to be moderately high because of the harsh marine environment. Professor Harries cites a report prepared by Parsons Brinkerhoff for the Royal Academy of Engineering in 2004, which estimated that the annual operation and maintenance costs of 2.2 cents per kilowatt hour (c/kWh), or the equivalent of generating 20 per cent of the total cost of generating electricity from waves.

Professor Harries says that until recently although the estimated cost of generating electricity from ocean power has been lower than the cost of generating electricity from solar photovoltaics, it has been significantly higher than the cost of generating electricity from large onshore wind farms or biomass plant.

The Royal Academy of Engineering 2004 report estimated the average costs of generating electricity from waves to be approximately 13.5 c/kWh and that this would decline to around 11.5 c/kWh. These cost estimates were higher than the estimated costs of generating electricity from offshore wind farms (10.5 c/kWh), but as wave energy resources are more reliable than wind resources, the lower need for standby generation with wave energy systems makes the total costs comparable. The more constant the wave energy, the lower the costs of generating electricity from waves, and some companies developing wave energy conversion technologies claim that using their technologies at sites with relatively constant wave resources will make it possible to generate electricity at a significantly lower cost.

The challenges ocean power developers face are indeed plentiful. However with companies such as Carnegie Corporation, Oceanlinx, BioPower Systems, Atlantis Resources and more looking to commercialise their technologies in Australian waters, the rewards of ocean power technology are appealing.