Riding a new wave of renewable energy

A concrete and steel structure anchored off the coast of Tasmania’s King Island is creating waves around the world.

The 200kW wave energy converter – the UniWave200 – operates by forming an “artificial blowhole” and is the world’s first unidirectional oscillating water column (OWC).

The Australian company behind the technology, Wave Swell Energy, has just completed a year-long trial that has been hailed by the King Island Mayor Julie Arnold as a “huge success”.

The island was this month named the overall winner of the 2022 Australian Sustainable Communities Tidy Towns Award for its determination to “make the community a more sustainable place for the future”, with specific mention of the role of Wave Swell Energy.

Wave Swell chief executive officer Paul Geason says reports of the trial results have drawn responses from across the globe.

“We are delightfully overwhelmed with the positive sentiment and responses we have received,” he says. “It’s been extraordinary.

“There has been interest and encouragement from many parts of the world – from Europe and the United States, from the Caribbean, South Africa and South America.

“People live on the coastlines and they observe the oceans. They observe the tides and the waves. It is the one remaining unharvested resource that can play such an important role.

“It can complement solar and wind. Wave energy is more predictable and reliable. How do you provide secure energy if the sun isn’t shining or the wind isn’t blowing? From our perspective, adding another source of renewable energy reduces the reliance on storage batteries and, as much as we love them, batteries are full of lithium.”

The UniWave200 features a chamber with an opening underneath the waveline. Waves cause water inside the chamber to rise and fall, compressing the air above which goes through flat valves into the atmosphere. When the trough of the waves follows, it creates a partial vacuum inside the chamber, and air is sucked back through the turbine, creating electricity.

In the past, OWC technology has been bidirectional. Air-flow through the UniWave200 goes only one way – into the chamber as the vacuum sucks it in.

Geason says it is this technology – simple and robust – that is largely behind the technology’s success.

“We have no moving parts underwater,” he says. “It is a steel and concrete chamber and all the mechanical parts are above the waterline, and the electrical system is secured.”

He says while the “moving parts” do require maintenance, work is far less of a challenge than for offshore energy converters where the mechanisms are underwater.

The trial-sized UniWave200 was manufactured in Launceston and towed to King Island. It is also possible to relocate it to other sites. The converter was integrated with King Island’s Advanced Hybrid Power Station run by Hydro Tasmania.

“King Island is a one-stop shop for energy generation,” Geason says. “The King Island network includes wind power and solar power. It is one of the most advanced hybrid integrated renewable grids in the world.

“Hydro Tasmania were very co-operative and collaborative.”

The $12.3 million project was awarded a $4 million grant by the Australian Renewable Energy Agency (ARENA) in 2019 for the UniWave200 to produce enough energy to power 200 homes. King Island Mayor Julie Arnold says it is providing about 3% of the island’s energy needs.

“From King Island’s point of view, about 70% of our energy is renewable,” she says. “We are really chuffed to be partnering with Wave Swell on this project. This is a project that other islands around the world can learn from and become more sustainable. And the community is right behind it.”

The island is believed to be one of the only locations around the world combining three forms of renewable energy to power the community.

The Australian Maritime College (AMC), based in Tasmania, has been working with Wave Swell Energy on the technology since 2016. 

“During this period, the WSE [Wave Swell Energy] technology has been extensively tested and optimised by performing many comprehensive series of physical scale model experiments in the AMC ocean wave basin and oscillating flow test rig at Launceston, Tasmania,” AMC Associate Professor Gregor Macfarlane notes in a letter summarising the college’s findings.

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A snapshot of the AMC data analysis concluded the following:

• UniWave200 is operating and exporting power consistently and efficiently across a broad range of sea states, from significant wave heights of 0.5m to 1.9m, and from peak wave periods of 9s to 17s.
• The turbine currently operates at a constant speed. However, the analysis of the operational data from the UniWave200 turbine confirms improvements can be made by incorporating a variable speed control system, optimising the turbine’s performance and increasing its conversion efficiency.
• The peak dynamic turbine efficiency, including losses, is approximately 76%. This is in close agreement with the idealised turbine peak efficiency of around 83%, which assumes steady flow and ignores losses.
• The custom-made one-way valves work efficiently and reliably, allowing for the successful operation of the world’s first unidirectional OWC.
• The power systems operate efficiently throughout all wave conditions.
• The measured full scale performance data from the UniWave200 WEC will feed into the design of larger commercial WECs, resulting in higher efficiencies and less uncertainty.

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The data analysis will continue throughout the duration of the project, providing insight and technical advice for further optimisation and will help guide Wave Swell Energy in their future research and development plans.

Wave Swell Energy also commissioned CSIRO to independently analyse the potential for capital cost and levelised cost of electricity (LCOE) reductions of the technology. The CSIRO findings projected that the WSE technology could be cost competitive with offshore wind within 25MW to 45MW of installed capacity.

It projected that wave energy, including the Wave Swell Energy technology, could achieve a 1.3% share of the global electricity market in 2050 if it could sustain an 18.23% learning rate. This equated to 170,000 MW of installed capacity and was greater than the total projected contribution of biomass and geothermal generation combined.

Geason says the King Island pilot was always intended to be a scaled-down demonstration version of future projects. Wave Swell Energy’s Project Bluefire will essentially build on the  learnings from the pilot to refine the technology –  including incorporating a variable speed control system for the turbine to speed up further and maximise efficiency.

“We are exploring what a design for a bigger unit will look like,” he says. “We don’t want to leap ahead too far – those mistakes have been made in renewable energy before. But it we are looking at a 1MW unit.”

He says while the unit would have five times the energy production capacity, it would not be five times the size once design refinements have been incorporated. The unidirectional oscillating water column technology can also be built into wavebreaks, with the potential to address two climate change concerns in one – inundation of low-lying islands and renewable energy production.

“Australia is a place we would dearly love to be able to deploy units,” Geason says. “We are starting to see a level of change in the narrative from the Federal Government in terms of support.

“But the immediate opportunities we see coming are in Europe, the United States, South Africa and India. India is very focused on accelerating to renewables.”

Now that wave energy is proving itself, Geason says, it’s time to see this renewable claim its role in the energy mix.