Wave Swell Energy: Using the motion of the ocean

wave swell energy

By Nichola Davies

Founded in 2016, Wave Swell Energy is currently developing a 200kW wave energy project that is to be installed in the ocean off the east coast of King Island between Tasmania and the Australian mainland.

CSIRO projections have revealed that the potential energy in waves along the southern coastline of Australia is five times the country’s current electricity usage. This is due to the strong Southern Ocean winds generating consistently large waves that travel northwards to Australia’s southern coastline.

The large, consistent and predictable swell provides ideal conditions for wave energy production – an advantage over other renewables.

“This means the longer time frames of the variability of wave energy allow it to be used to complement existing fossil fuel base load sources without creating surges in power delivery,” Wave Swell CEO Dr Tom Denniss explains.

“It can be used in conjunction with traditional base load sources with a seamless transition between renewable and fossil fuel sources.

“For example, as waves increase in size, producing more energy, a coal-fired power station can gradually scale back its production, and vice versa.”

CSIRO’s research reveals wave energy could contribute up to 11 per cent of Australia’s energy needs by 2050.

But, the development of a wave energy industry in Australia has been slow and choppy, with several projects being abandoned due to financial troubles. US company Ocean Power Technologies unveiled grand plans to develop a $232 million, 19 mW project near Portland, Victoria, but abandoned the project in 2014. We also saw Carnegie Clean Energy go into liquidation earlier this year citing financial troubles, however the company is back on its feet now with wave energy and a new digital strategy at the core of its business. In general, the sector is in early development phase. Australia’s huge potential for wave energy makes the technology worth investigating.

As such, the Australian Renewable Energy Agency (ARENA) has just committed $4 million to Wave Swell Energy to install a pilot-scale wave energy converter off the coast of King Island.

The $12.3 million project will involve the design, construction, installation and operation of the UniWave 200, a 200 kW wave energy device, the electricity of which can be transmitted to the shore and integrated with the King Island microgrid, operated by Hydro Tasmania.
The microgrid also received $11 million in funding from ARENA in 2011 to demonstrate the integration of several renewable resources and energy management technologies.

Based on the concept of a unidirectional oscillating water column (OWC), Wave Swell Energy’s technology offers an ‘artificial blowhole’ that allows waves to enter a hollow chamber that is open underneath the waterline and drive a turbine. Water rises and falls inside the chamber, causing the pressure of the air trapped above to change between negative and positive pressure. The pressure fluctuations force the air to pass through the turbine at the top of the chamber, generating electricity.

 The technology works on unidirectional airflow, which simplifies the associated air turbine. This is in contrast to conventional OWC technologies that are bidirectional, requiring air turbines to operate on reversing flow.

A bidirectional system necessitates either an inefficient or a complex turbine with pitching blades, or a complicated system requiring the redirection of flow on each cycle. Being unidirectional, Wave Swell Energy’s technology offers a robust, cheap, and efficient turbine over bidirectional systems.

In addition, unlike the existing deepwater applications with floating units that result in high maintenance costs, WSE’s units involve no moving parts in the water. In fact, OWC devices are constructed from concrete, using simple molds and steel reinforcing. It sits on the shallow (5.75 m deep) sandy seabed under its own weight, requiring a small footprint and no anchoring. The devices can be re-floated and towed to another location, allowing ease of access for maintenance and operation.

Further, WSE’s technology covers a range of uses apart from electricity generation. It also proves to be beneficial to combat the issue of coastal erosion. The traditional methods of dealing with this problem are installing breakwaters, sea walls, and groynes that require a significant capital outlay, which is a sunk cost. On the other hand, WSE units, when deployed in close proximity to each other, act as a breakwater or sea wall while converting that energy into electricity. This not only protects the coastline from erosion but also generates an annuity-style revenue stream from the electricity generated.

Dr Denniss, who developed the idea of commercialising the unidirectional oscillating water column technology in collaboration with Scott Hunter, says the pilot, which is expected to be operational in Q2 2020, aims to demonstrate the technology’s viability.

“The ARENA funding is obviously vital to funding the King Island project, but it also gives a huge tick to the technology and its commercial potential as ARENA assisted on an exhaustive due diligence process before providing the grant,” Mr Denniss said.

“Our technology is now on the cusp of true commercial viability, thereby providing clients with a solution that is finally cost effective and environmental friendly.

“In five years I see it deployed in remote island locations with perhaps a couple of large-scale grid connected units, with a likely a hydrogen production project included.

“In 10 years the installed capacity should have increased five- to ten-fold on that of the first five years, with a similar multiple increase after 20 years.

“In 20 years, we should be seeing a lot more mainland grid applications.”